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  • 1751.
    Yuen, Katarina
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Thomas, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Grabbe, Mårten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Deglaire, Paul
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Bouquerel, Mathias
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Österberg, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Matching a permanent magnet synchronous generator to a fixed pitch vertical axis turbine for marine current energy conversion2009Inngår i: IEEE Journal of Oceanic Engineering, ISSN 0364-9059, E-ISSN 1558-1691, Vol. 34, nr 1, s. 24-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Extracting energy from a free-flow marine current using a vertical axis fixed pitch turbine requires a generator that can handle varying speeds and loads, since such a turbine gives maximum power capture for a fixed tip speed ratio. A prototype of such a generator has been designed and constructed. In this paper, its variable speed and load operation is evaluated, both in terms of how the constructed generator performs in relation to simulations, and in terms of how the generator could perform with three different fixed pitch turbines. Measurements of root mean square (RMS) voltage and current differ 10% from simulations. Performance analysis with example turbines shows that the generator can match fixed tip speed ratio operation of several turbines for current speeds between 0.5 and 2.5 m/s.

    Fulltekst (pdf)
    fulltext
  • 1752.
    Yusop, Norbayah
    et al.
    Univ Kebangsaan Malaysia, Space Sci Ctr ANGKASA, Inst Climate Change, Bangi 43600, Selangor, Malaysia;Univ Tekn Malaysia Melaka, Fak Kejuruteraan Elekt & Kejuruteraan Komputer, Ctr Telecommun Res & Innovat CeTRI, Atmospher & Lightning Res Lab, Durian Tunggal 76100, Melaka, Malaysia.
    Ahmad, Mohd Riduan
    Univ Tekn Malaysia Melaka, Fak Kejuruteraan Elekt & Kejuruteraan Komputer, Ctr Telecommun Res & Innovat CeTRI, Atmospher & Lightning Res Lab, Durian Tunggal 76100, Melaka, Malaysia.
    Abdullah, Mardina
    Univ Kebangsaan Malaysia, Fac Engn & Built Environm, Ctr Adv Elect & Commun Engn, Bangi 43600, Selangor, Malaysia;Univ Kebangsaan Malaysia, Inst Climate Change, Bangi 43600, Selangor, Malaysia.
    Mohd Esa, Mona Riza
    Univ Teknol Malaysia, Fac Engn, Sch Elect Engn, Inst High Voltage & High Current IVAT, Skudai 81310, Johor Bahru, Malaysia.
    Mohammad, Sulaiman Ali
    Univ Teknol Malaysia, Fac Engn, Sch Elect Engn, Inst High Voltage & High Current IVAT, Skudai 81310, Johor Bahru, Malaysia.
    Suparta, Wayan
    Univ Pembangunan Jaya, Dept Informat, South Tangerang 15413, Banten, Indonesia.
    Gulisano, Adriana Maria
    Inst Antartico Argentino DNA, RA-1248 Buenos Aires, DF, Argentina;UBA, CONICET, Inst Astron & Fis Espacio, RA-1053 Buenos Aires, DF, Argentina;Univ Buenos Aires, FCEyN, Dept Fis, RA-1053 Buenos Aires, DF, Argentina.
    Cooray, Vernon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Seasonal Analysis of Cloud-To-Ground Lightning Flash Activity in the Western Antarctica2019Inngår i: Atmosphere, ISSN 2073-4433, E-ISSN 2073-4433, Vol. 10, nr 12, artikkel-id 744Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a seasonal analysis of cloud-to-ground (CG) lightning flash activity in the Western Antarctica using a lightning detector sensor installed at the Carlini Base station. Data obtained from the detection system between February and December 2017 were analyzed. Three common locations and areas of composite active thunderstorms (labelled storm regions A, B, and C) were detected by the sensor within a 1000 km radius from the station. Storm region A was located to the northwest (N/W) of the station and covered the Amundsen/Bellingshausen Sea (ABS), whereas storm region C was located on the southeastern (S/E) side of the station over the Weddell Sea (WS), with distances ranging from 500 to 800 km and bearings of 270 degrees to 360 degrees and 90 degrees to 180, respectively. Storm region B was located around 100 km from the station with the bearings of stroke taken from 0 degrees to 360 degrees. A total of 2,019,923 flashes were detected, of which 43.01% were positive CG and 56.99% were negative CG flashes. The analysis revealed that more than 96% of the CG flashes (both positive CG and negative CG) were produced during the summer and fall seasons as compared with less than 4% during the winter and spring seasons. Most detected lightning strokes (>85%) were located in the central area around the station produced by storm region B and less than 15% were produced by storm region A and storm region C, located in the ocean areas over the Amundsen/Bellingshausen Sea and the Weddell Sea.

    Fulltekst (pdf)
    FULLTEXT01
  • 1753.
    Yusop, Norbayah
    et al.
    Univ Kebangsaan Malaysia, Inst Climate Change, Space Sci Ctr ANGKASA, Bangi 43600, Selangor Darul, Malaysia;Univ Tekn Malaysia Melaka, Fak Kejuruteraan Elekt & Kejuruteraan Komputer, Atmospher & Lightning Res Lab, Ctr Telecommun Res & Innovat CeTRI, Durian Tunggal 76100, Melaka, Malaysia.
    Ahmad, Mohd Riduan
    Univ Tekn Malaysia Melaka, Fak Kejuruteraan Elekt & Kejuruteraan Komputer, Atmospher & Lightning Res Lab, Ctr Telecommun Res & Innovat CeTRI, Durian Tunggal 76100, Melaka, Malaysia.
    Abdullah, Mardina
    Univ Kebangsaan Malaysia, Inst Climate Change, Bangi 43600, Selangor Darul, Malaysia;Univ Kebangsaan, Fac Engn & Built Environm, Ctr Adv Elect & Commun Engn, Bangi, Malaysia.
    Zainudin, Siti Khalijah
    Univ Kebangsaan Malaysia, Inst Climate Change, Space Sci Ctr ANGKASA, Bangi 43600, Selangor Darul, Malaysia.
    Nor, Wan Nur Arina Wan Mohd
    Univ Kebangsaan Malaysia, Inst Climate Change, Space Sci Ctr ANGKASA, Bangi 43600, Selangor Darul, Malaysia.
    Alhasa, Kemal Maulana
    Univ Kebangsaan Malaysia, Inst Climate Change, Space Sci Ctr ANGKASA, Bangi 43600, Selangor Darul, Malaysia.
    Esa, Mona Riza Mohd
    Univ Teknol Malaysia, Inst High Voltage & High Current IVAT, Skudai 81310, Johor Bharu, Malaysia.
    Sabri, Muhammad Haziq Mohamad
    Univ Tekn Malaysia Melaka, Fak Kejuruteraan Elekt & Kejuruteraan Komputer, Atmospher & Lightning Res Lab, Ctr Telecommun Res & Innovat CeTRI, Durian Tunggal 76100, Melaka, Malaysia.
    Suparta, Wayan
    Pembangunan Jaya Univ, Dept Informat, South Tangerang 15413, Banten, Indonesia.
    Maria Gulisano, Adriana
    Inst Antartico Argentino DNA, RA-1248 Buenos Aires, DF, Argentina;UBA, CONICET, Inst Astron & Fis Espacio, Buenos Aires, DF, Argentina;Univ Buenos Aires, FCEyN, Dept Fis, Buenos Aires, DF, Argentina.
    Cooray, Vernon
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Cloud-to-Ground lightning observations over the Western Antarctic region2019Inngår i: Polar Science, ISSN 1873-9652, E-ISSN 1876-4428, Vol. 20, s. 84-91Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the observations and characterization of Cloud-to-Ground (CG) lightning activity in Western Antarctica in a region that covers the Amundsen/Bellingshausen Sea (ABS), the Antarctic Peninsula (AP) and the Weddell Sea (WS). Lightning data have been collected by a lightning detector (Boltek LD-350) and an atmospheric electric field mill (EFM-100) sensors deployed at the Carlini Base on the Antarctic Peninsula (CARL: 62.23 degrees S, 58.63 degrees W). The flash rate and flash multiplicity were analysed for three different seasons within a 1,000 km range, starting at the end of summer (February 2017) and ending in winter (July 2017). Three storm days for each month (within the 1,000 km radius from the LD sensor) with three composite active thunderstorms (labelled as Storm region A, B, and C) for each day have been selected from a collection of storm days between February and July 2017. A total of 355,899 flashes have been recorded with 156,190 Positive CG and 199,709 Negative CG flashes from these 54 thunderstorms. In total, Positive CG flash counts made up around 43.9% of the total detected CG flashes. Most of the Positive CG flashes (> 80%) had only 1 or 2 strokes with a maximum number of 5. For Negative CG flashes, the average multiplicity and the maximum multiple stroke were 1.2 and 16 respectively. Most CG flashes were detected during the summer and fall months. Positive CG flashes were prevalent in Western Antarctic storms even during the winter. The mean, median and range of the ratio of Positive CG to Negative CG flashes were 0.7, 0.718 and 0.217-1.279, respectively.

  • 1754.
    Zeng, Wei
    et al.
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Yang, Jiandong
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Tang, Renbo
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Yang, Weijia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Extreme water-hammer pressure during one-after-another load shedding in pumped-storage stations2016Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 99, s. 35-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The intermittent and unpredictable wind and solar power leads to the frequent transient processing of pumped-storage stations, increasing the probability of load shedding. When one turbine sheds its load, the other turbines in the same hydraulic unit become overloaded and may shed their loads, which is referred to as a "one-after-another (OAA)" load-shedding process. An extremely high water-hammer pressure (WHP), namely, high spiral case pressure (SCP) or low draft tube pressure (DTP), may arise in this case, directly threatening the safety of the PSS. The objective of this study was to theoretically determine the hydraulic connections between the turbines and reveal the mechanism of the rapid rise in the WHP under the OAA load-shedding conditions. Theoretical derivations inferred that the drastic pressure changes in a trail shedding turbine (TST) are caused by the hydraulic connection with the lead shedding turbine (LST) in the S region. Furthermore, numerical simulations and model experiments were performed for the OAA load-shedding process, which confirmed the validity of the theoretical analysis. Finally, an analysis was conducted on the distribution of the water inertia in the upstream and downstream branch pipes, and engineering measures were proposed to guarantee the safe operation of PSS systems.

  • 1755.
    Zeng, Wei
    et al.
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Yang, Jiandong
    Wuhan Univ, State Key Lab Water Resources & Hydropower Engn S, Wuhan 430072, Peoples R China..
    Yang, Weijia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Instability analysis of pumped-storage stations under no-load conditions using a parameter-varying model2016Inngår i: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 90, s. 420-429Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The S-shaped characteristics of a pump turbine make its rotational speed unstable when it starts up under no-load conditions with low head, affecting its ability to connect to the grid. Although advanced strategies for controlling the speed governor can alleviate this problem, they cannot fundamentally resolve the internal mechanisms that cause difficulties with a grid connection. Therefore, this study set out to theoretically explore the root cause of the instability and the dominant factors influencing it. A correlation fitting process was used to simplify the transcendental function for the pipe flow in elastic mode into a high-precision and low-order linear equation. Next, a detailed study of the two key factors affecting system stability (pump turbine S-shaped characteristics and water elasticity) was carried out based on the system model, and a comprehensive parameter that reflects the no-load characteristics was extracted. Furthermore, the Laplace transform and inverse transform decomposition were used to obtain a mathematical expression for the no-load oscillation in order to analyze the oscillation characteristics. Finally, simulations of no-load oscillations under various heads were performed to further validate the accuracy of the extracted comprehensive parameter for the no-load stability.

  • 1756. Zhang, X.
    et al.
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Gorini, G.
    Nocente, M.
    Fan, T.
    Yuan, X.
    Xie, X.
    Chen, Z.
    Second generation fusion neutron time-of-flight spectrometer at optimized rate for fully digital data acquisition2014Inngår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, nr 4, s. 043503-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The progress on high-rate event recording of data is taken as starting point to revisit the design of fusion neutron spectrometers based on the TOF (time-of-flight) technique. The study performed was aimed at how such instruments for optimized rate (TOFOR) can be further developed to enhance the plasma diagnostic capabilities based on measurement of the 2.5 MeV dd neutron emission from D plasmas, especially the weak spectral components that depend on discrimination of extraneous events. This paper describes a design (TOFOR II) adapted for use with digital wave form recording of all detector pulses providing information on both amplitude (pulse height) and timing. The results of simulations are presented and the performance enhancement is assessed in comparison to the present.

  • 1757. Zhang, Xing
    et al.
    Chen, Zhongjing
    Peng, Xingyu
    Hu, Zhimeng
    Du, Tengfei
    Cui, Zhiqiang
    Xie, Xufei
    Yuan, Xi
    Fan, Tieshuan
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Gorini, G.
    Nocente, M.
    Tardocchi, M.
    Hu, Liqun
    Zhong, Guoqiang
    Lin, Shiyao
    Wan, Baonian
    Li, Xiangqing
    Zhang, Guohui
    Chen, Jinxiang
    Diagnosing NB plasmas on the EAST tokamak with new time-of-flight neutron spectrometer2014Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 54, nr 10, s. 104008-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The new neutron spectrometer time-of-flight enhanced diagnostics (TOFED) for the EAST tokamak is presented and its characteristics are described in terms of simulation results, as well as the interface in the torus hall along with new neutral beam (NB) injectors. The use of TOFED for studies of the slowing down of NB-injected deuterons is illustrated. The implications of measuring the neutron emission on a long pulse machine are discussed together with the experimental challenges and diagnostic possibilities approaching those to be encountered in continuous operation.

  • 1758.
    Zhao, Xuan-lie
    et al.
    Dalian Univ Technol, State Key Lab Coastal & Offshore Engn, Dalian 116023, Peoples R China.
    Ning, De-zhi
    Dalian Univ Technol, State Key Lab Coastal & Offshore Engn, Dalian 116023, Peoples R China.; Hohai Univ, State Key Lab Hydrol Water Resources & Hydraul En, Nanjing 210098, Jiangsu, Peoples R China..
    Göteman, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Kang, Hai-gui
    Dalian Univ Technol, State Key Lab Coastal & Offshore Engn, Dalian 116023, Peoples R China.
    Effect of the PTO damping force on the wave pressures on a 2-D wave energy converter2017Inngår i: Journal of Hydrodynamics, ISSN 1001-6058, E-ISSN 1000-4874, Vol. 29, nr 5, s. 863-870Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The information of the wave loads on a wave energy device in operational waves is required for designing an efficient wave energy system with high survivability. It is also required as a reference for numerical modeling. In this paper, a novel system, which integrates an oscillating wave energy converter with a pile-restrained floating breakwater, is experimentally investigated in a 2-D wave flume. The measurements of the wave pressure on the wet-surface of the device are made as the function of the power take-off (PTO) damping force. It is shown that the wave pressure is significantly affected by the PTO system, in particular, at the edges, and the wave pressure varies under different wave conditions. From the results, conclusions can be drawn on how the PTO damping force and wave conditions affect the loads on the device, which is of engineering concern for constructing safe and reliable devices.

  • 1759.
    Zhao, Xuanlie
    et al.
    State Key of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China.
    Ning, Dezhi
    State Key of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China.
    Kang, Haigui
    State Key of Coastal and Offshore Engineering, Dalian University of Technology, Dalian, China.
    Göteman, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Effect of PTO on the dynamics of a WEC-type floating breakwater2016Konferansepaper (Fagfellevurdert)
  • 1760.
    Zisimopoulos, Dimitrios
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    En elektrifiering av den interna busstrafiken på Stockholm Arlanda Airport2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Functional and cost effective systems for the full electrification of a bus network are areas of intense research and development. The electrification can be accomplished using different technological solutions, for example using opportunity charging or using an electric road system – ERS. Both opportunity charging and ERS have the potential to be integrated into already existing bus lines. With opportunity charging, the regular dwell time at the end stops is used for the bus to recharge its batteries and with an ERS the bus can charge dynamically along the road. The purpose of this report is to analyze how the existing Alfa- and Beta line at Stockholm Arlanda Airport, in a functional and cost effective way, can be electrified using either opportunity charging or an ERS. The tradeoff between required charging power, battery capacity and the necessity to change the existing running schedule is explained in detail. In addition, the impact on the electrical grid is analyzed based on different load profiles of different charging stations using different power levels. The analysis is based on real data from the Alfa – and Beta line with its existing buses, the electrical grid at Arlanda and data provided by both the leading (electrical) bus manufacturers and the leading charging infrastructure manufacturers.  The outcome of this report suggests that a full electrification of the existing Alfa- and Beta line has the potential to lower CO2-emissions and energy use at a functional and cost effective way.

    Fulltekst (pdf)
    fulltext
  • 1761. Zupanski, M.
    et al.
    Fletcher, S.
    Navon, I.
    Uzunoglu, Bahri
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Heikes, R.
    Randall, D.
    Ringler, T.
    Daescu, D.
    Initiation of ensemble data assimilation2006Inngår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 58, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The specification of the initial ensemble for ensemble data assimilation is addressed. The presented work examines the impact of ensemble initiation in the Maximum Likelihood Ensemble Filter (MLEF) framework, but is also applicable to other ensemble data assimilation algorithms. Two methods are considered: the first is based on the use of the Kardar- Parisi-Zhang (KPZ) equation to form sparse random perturbations, followed by spatial smoothing to enforce desired correlation structure, while the second is based on the spatial smoothing of initially uncorrelated random perturbations. Data assimilation experiments are conducted using a global shallow-water model and simulated observations. The two proposed methods are compared to the commonly used method of uncorrelated random perturbations. The results indicate that the impact of the initial correlations in ensemble data assimilation is beneficial. The root-mean-square error rate of convergence of the data assimilation is improved, and the positive impact of initial correlations is notable throughout the data assimilation cycles. The sensitivity to the choice of the correlation length scale exists, although it is not very high. The implied computational savings and improvement of the results may be important in future realistic applications of ensemble data assimilation.

  • 1762.
    Ågren, O.
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Moiseenko, V.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Johansson, C.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, N.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Gyro center invariant and associated diamagnetic current2005Inngår i: Physics of Plasmas, Vol. 12, nr 122503, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
  • 1763.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Berg, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Leijon, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    A time-dependent potential flow theory for the aerodynamics of vertical axis wind turbines2005Inngår i: Journal of Applied Physics, Vol. 97, nr 104913, s. 1-12Artikkel i tidsskrift (Fagfellevurdert)
  • 1764.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V. E.
    Kharkov Inst Phys & Technol, Natl Sci Ctr, Inst Plasma Phys, Akad St 1, UA-61108 Kharkov, Ukraine..
    On improved confinement in mirror plasmas by a radial electric field2017Inngår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 59, nr 11, artikkel-id 115001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A weak radial electric field can suppress radial excursions of a guiding center from its mean magnetic surface. The physical origin of this effect is the smearing action by a poloidal E x B rotation, which tend to cancel out the inward and outward radial drifts. A use of this phenomenon may provide larger margins for magnetic field shaping with radial confinement of particles maintained in the collision free idealization. Mirror fields, stabilized by a quadrupolar field component, are of particular interest for their MHD stability and the possibility to control the quasi neutral radial electric field by biased potential plates outside the confinement region. Flux surface footprints on the end tank wall have to be traced to avoid short-circuiting between biased plates. Assuming a robust biasing procedure, moderate voltage demands for the biased plates seems adequate to cure even the radial excursions of Yushmanov ions which could be locally trapped near the mirrors. Analytical expressions are obtained for a magnetic quadrupolar mirror configuration which possesses minimal radial magnetic drifts in the central confinement region. By adding a weak controlled radial quasi-neutral electric field, the majority of gyro centers are predicted to be forced to move even closer to their respective mean magnetic surface. The gyro center radial coordinate is in such a case an accurate approximation for a constant of motion. By using this constant of motion, the analysis is in a Vlasov description extended to finite beta. A correspondence between that Vlasov system and a fluid description with a scalar pressure and an electric potential is verified. The minimum B criterion is considered and implications for flute mode stability in the considered magnetic field is analyzed. By carrying out a long-thin expansion to a higher order, the validity of the calculations are extended to shorter and more compact device designs.

  • 1765.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V. E.
    Radial constant of motion for particles in magnetic mirror fields2014Inngår i: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 56, nr 9, s. 095026-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is crucial for magnetic fusion devices that particle confinement occurs for long periods in a magnetic flux tube, and radial loss from the flux tube by a collision-free radial drift needs to be eliminated. Longitudinal, as well as radial, confinement is required. Two standard constants of motion, the energy and the magnetic moment of the gyrating particle, provide longitudinal confinement. A third constant of motion, which implies bounded radial motion, would be sufficient for radial confinement, but it is often impossible to identify such an invariant. A closed form expression for a radial invariant is derived for magnetic mirrors with a stabilizing quadrupolar field. A weak radial electric field, controlled by electrically biased endplates, is a tool for making a collision-free motion radially bounded in open systems. Experimental results in such magnetic confinement schemes indicate a qualitative agreement with our predictions for the existence of a radial invariant. Voltage and power requirements for the biased endplates are vanishingly small if the magnetic drifts are minimized in the magnetic field design. The power requirements to sustain the biased potentials are expected to be vanishingly small for a gross stable plasma.

  • 1766.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V. E.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Radial Drift Invariant In Long-Thin Mirrors2012Inngår i: Fusion for Neutrons and Subcritical Nuclear Fission: Fusion for Neutrons and Subcritical Nuclear Fission / [ed] Jan Källne, Dimitri Ryutov, Giuseppe Gorini, Carlo Sozzi, Marco Tardocchi, 2012, s. 255-258Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In omnigenous systems, the guiding centers are constrained to move on magnetic surfaces. Since a magnetic surface is determined by a constant radial Clebsch coordinate, omnigenuity implies that the guiding center radial coordinate (the Clebsch coordinate) is constant. Near omnigenuity is probably a requirement for high quality confinement and in such systems only small oscillatory radial banana guiding center excursions from the average drift surface occur. The guiding center radial coordinate is then the leading order term for a more precise radial drift invariant I-r, where higher order corrections arise from the oscillatory "banana ripple" associated with the excursions from the mean drift magnetic surface. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirror equilibria. The formula for the invariant is then used in a Vlasov distribution function. To model radial density profiles, it is necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are also compared with standard fluid approaches. In several aspects, the fluid and Vlasov system with the radial invariant give analogous formulas. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.

  • 1767.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V. E.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Anglart, H.
    Hybrid Reactor Studies Based on the Straight Field Line Mirror2013Inngår i: Fusion science and technology, ISSN 1536-1055, E-ISSN 1943-7641, Vol. 63, nr 1T, s. 52-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The straight field line mirror (SFLM) hybrid reactor studies aim to identify a concept where the safety of fission power production could be enhanced. A fusion neutron source could become a mean to achieve this. The SFLM studies address critical issues such as reactor safety, natural circulation of coolants, steady state operation for a year or more and means to avoid too strong material loads by a proper geometrical arrangement of the reactor components. A key result is that power production may be possible with a fusion Q factor as low as 0.15. This possibility arises from the high power amplification by fission, which within reactor safety margins may exceed a factor of 100. The requirements on electron temperature are dramatically lower for a fusion hybrid compared to a stand-alone fusion reactor. This and several other factors are important for our choice to select a mirror machine for the fusion hybrid reactor studies.

  • 1768.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Moiseenko, V.E.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Four motional invariants in axisymmetric tori equilibria2006Inngår i: Physics of Plasmas, Vol. 13, s. 052501:1-9Artikkel i tidsskrift (Fagfellevurdert)
  • 1769.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V.E.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Anglart, H.
    Hybrid reactor studies based on the straight field line mirror: Invited talk2012Konferansepaper (Fagfellevurdert)
  • 1770.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V.E.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Anglart, H.
    The straight field line mirror concept aiming at a hybrid reactor: Oral presentation2012Konferansepaper (Fagfellevurdert)
  • 1771.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, Vladimir E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Conceptual study of a straight field line mirror hybrid reactor2011Inngår i: Problems of Atomic Science and Technology, ISSN 1562-6016, nr 1, s. 3-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A hybrid reactor based on the straight field line mirror (SFLM) with magnetic expanders at the ends is proposed as a compact device for transmutation of nuclear waste and power production. Compared to a fusion reactor, plasma confinement demands can be relaxed if there is a strong energy multiplication by the fission reactions, i.e. Q(r)=Pfission/Pfusion >> 1. The values of Q(r) is primarily restricted by fission reactor safety requirements. For the SFLM, computations suggest that values of Q(r) ranging up to 150 are consistent with reactor safety. In a mirror hybrid device with Q(r) > 100, the lower bound on the electron temperature for power production can then be estimated to be around 400 eV, which may be achievable for a mirror machine. The SFLM with its quadrupolar stabilizing fields does not rely on plasma flow into the expanders for MED stability, and a scenario with plasma density depletion in the expanders is a possibility to increase the electron temperature. Efficient power production is predicted with a fusion Q= 0.15 and an electron temperature around 500 eV. A fusion power of 10 MW could then be amplified to 1.5 GW fission power in a compact 25 m long hybrid mirror machine. Beneficial features are that all sensitive equipment can be located outside the neutron rich region and a steady state power production seems possible. Self circulation of the lead coolant, which is useful for heat removal if coolant pumps cease to operate, could be arranged by orienting the magnetic axis vertically. Results from studies on plasma equilibrium and stability, coil designing, RF heating and neutron computations are presented.

  • 1772.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, Vladimir E
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Radial Drift Invariant in Long-Thin Mirrors2012Inngår i: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 66, nr 28Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In omnigenous systems, guiding centers are constrained to move on magnetic surfaces. Sincea magnetic surface is determined by a constant radial Clebsch coordinate, omnigeneity implies that theguiding center radial coordinate (the Clebsch coordinate) is a constant of motion. Near omnigeneity isprobably a requirement for high quality confinement and in such systems only small oscillatory radialbanana guiding center excursions from the average drift surface occur. The guiding center radial coordinateis then the leading term for a more precise radial drift invariant Ir, corrected by oscillatory “bananaripple” terms. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirrorequilibria. The formula for the invariant is then used in a Vlasov distribution function. Comparisons arefirst made with Vlasov equilibria using the adiabatic parallel invariant. To model radial density profiles, itis necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are alsocompared with a fluid approach. In several aspects, the fluid and Vlasov system with the radial invariantgive analogous predictions. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.

    Fulltekst (pdf)
    fulltext
  • 1773.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, Vladimir E
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Studies of a Straight Field Line Mirror with emphasis on fusion-fission hybrids2010Inngår i: Fusion science and technology, ISSN 1536-1055, E-ISSN 1943-7641, Vol. 57, nr 4, s. 326-334Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The straight field line mirror (SFLM) field with magnetic expanders beyond the confinement region is proposed as a compact device for transmutation of nuclear waste and power production. A design with reactor safety and a large fission-to-fusion energy multiplication is analyzed. Power production is predicted with a fusion Q = 0.15 and an electron temperature of [approximately]500 eV. A fusion power of 10 MW may be amplified to 1.5 GW of fission power in a compact hybrid mirror machine. In the SFLM proposal, quadrupolar coils provide stabilization of the interchange mode, radio-frequency heating is aimed to produce a hot sloshing ion plasma, and magnetic coils are computed with an emphasis on minimizing holes in the fission blanket through which fusion neutrons could escape. Neutron calculations for the fission mantle show that nearly all fusion neutrons penetrate into the fission mantle. A scenario to increase the electron temperature with a strong ambipolar potential suggests that an electron temperature exceeding 1 keV could be reached with a modest density depletion by two orders in the expander. Such a density depletion is consistent with stabilization of the drift cyclotron loss cone mode.

    Fulltekst (pdf)
    fulltext
  • 1774.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, Vladimir E
    Noack, Klaus
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    The straight field line mirror concept and applications2008Inngår i: Problems of Atomic Science and Technology, ISSN 1562-6016, nr 6, s. 8-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The straight field line mirror field is a marginal minimum B field with straight nonparallel field lines. This field gives optimal ellipticity, the drift surfaces lie on a magnetic surface, radiofrequency heating of the plasma is predicted to be efficient and MHD stability is provided by the minimum B property. One intended application of the magnetic field configuration is energy production and transmutation of spent nuclear fuel in a fusion-fission machine, where the mirror confined plasma is surrounded by a fission mantle. Reactor safety can be increased with a subcritical fission mantle, and the fission power can exceed the fusion power by as much as a factor of 150 with a reasonable condition for reactor safety margins, and this provides a basis for a compact reactor design. The straight field line mirror concept can also be of interest as a plasma source for synthesis of sophisticated materials. PACS: 28.52.Av, 28.41.Ak.

  • 1775.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, Vladimir
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Noack, K
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Fusion-fission hybrid reactor studies for the straight field line mirror2011Inngår i: Fusion science and technology, ISSN 1536-1055, E-ISSN 1943-7641, Vol. 59, nr 1T, s. 166-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A comparatively small mirror fusion hybrid device may be developed for industrial transmutation and energy production from spent nuclear waste. This opportunity ensues from the large fission to fusion energy multiplication ratio, Q(r) =P-fis/P-fus <= 150, in a subcritical fusion device surrounded by a fission mantle with the neutron multiplicity k(eff) approximate to 0.97. The geometry of mirror machines is almost perfectly suited for a hybrid reactor application, and the requirements for plasma confinement can be dramatically relaxed in correspondence with a high value of Q(r) Steady state power production in a mirror hybrid seems possible if the electron temperature reaches 500 eV. A moderately low fusion Q factor, the ratio of fusion power to the power necessary to sustain the plasma, could be sufficient, i.e. Q approximate to 0.15. Theoretical predictions for the straight field line mirror (SFLM) concept are presented, including results from radio frequency heating, neutron Monte Carlo and magnetic coil computations. Means to achieve an electron temperature of 500 eV are briefly discussed. The basic study considers a 25 m long confinement region with 40 cm plasma radius with 10 MW fusion power and a power production of 1.5 GW thermal.

  • 1776.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Moiseyenko, Vladimir
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Constants of motion in a minimum-B mirror magnetic field2005Inngår i: Physical Review E, Vol. 72, nr 026408, s. 1-5Artikkel i tidsskrift (Fagfellevurdert)
  • 1777.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Noack, Klaus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Moiseenko, V. E.
    Hagnestål, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Källne, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Anglart, H.
    The Hybrid Reactor Project Based On The Straight Field Line Mirror Concept2012Inngår i: Fusion for Neutrons and Subcritical Nuclear Fission: Proceedings of the International Conference / [ed] Jan Källne, Dimitri Ryutov, Giuseppe Gorini, Carlo Sozzi, Marco Tardocchi, 2012, s. 173-185Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The straight field line mirror (SFLM) concept is aiming towards a steady-state compact fusion neutron source. Besides the possibility for steady state operation for a year or more, the geometry is chosen to avoid high loads on materials and plasma facing components. A comparatively small fusion hybrid device with "semi-poor" plasma confinement (with a low fusion Q factor) may be developed for industrial transmutation and energy production from spent nuclear fuel. This opportunity arises from a large fission to fusion energy multiplication ratio, Q(r) = P-fis/P-fus >> 1. The upper bound on Q(r) is primarily determined by geometry and reactor safety. For the SFLM, the upper bound is Q(r)approximate to 150, corresponding to a neutron multiplicity of k(eff) =0.97. Power production in a mirror hybrid is predicted for a substantially lower electron temperature than the requirement T-e approximate to 10 keV for a fusion reactor. Power production in the SFLM seems possible with Q approximate to 0.15, which is 10 times lower than typically anticipated for hybrids (and 100 times smaller than required for a fusion reactor). This relaxes plasma confinement demands, and broadens the range for use of plasmas with supra-thermal ions in hybrid reactors. The SFLM concept is based on a mirror machine stabilized by qudrupolar magnetic fields and large expander tanks beyond the confinement region. The purpose of the expander tanks is to distribute axial plasma loss flow over a sufficiently large area so that the receiving plates can withstand the heat. Plasma stability is not relying on a plasma flow into the expander regions. With a suppressed plasma flow into the expander tanks, a possibility arise for higher electron temperature. A brief presentation will be given on basic theory for the SFLM with plasma stability and electron temperature issues, RF heating computations with sloshing ion formation, neutron transport computations with reactor safety margins and material load estimates, magnetic coil designs as well as a discussion on the implications of the geometry for possible diagnostics. Reactor safety issues are addressed and a vertical orientation of the device could assist passive coolant circulation. Specific attention is put to a device with a 25 m long confinement region and 40 cm plasma radius in the mid-plane. In an optimal case (k(eff) = 0.97) with a fusion power of only 10 MW, such a device may be capable of producing a power of 1.5 GW(th).

  • 1778.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Magnetic mirror minimum B field with optimal ellipticity2004Inngår i: Physics of plasmas, Vol. 11, nr 11Artikkel i tidsskrift (Fagfellevurdert)
  • 1779.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Minimum B field with optimal ellipticity and idea for improved axial confinement by tuned ICRH cycles2005Inngår i: Transactions of Fusion Science and Technology, ISSN 1536-1055, Vol. 47, nr 1 T, s. 285-287Artikkel i tidsskrift (Fagfellevurdert)
  • 1780.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Rigid rotation symmetry of a marginally stable minimum B field and analytical expressions of the flux coordinates2005Inngår i: Physics of Plasmas, Vol. 12, nr 042505, s. 1-5Artikkel i tidsskrift (Fagfellevurdert)
  • 1781.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Sloshing ion distribution function in a minimum B mirror field2005Inngår i: Physics of Plasmas, Vol. 12, nr 022504, s. 1-5Artikkel i tidsskrift (Fagfellevurdert)
  • 1782.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Theoretical study of increased electron temperature in mirror machines by tuned ion cyclotron resonance heating cycles2005Inngår i: Physics of Plasmas, Vol. 12, nr 022506, s. 1-10Artikkel i tidsskrift (Fagfellevurdert)
  • 1783.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Theoretical study of minimum B field with optimal ellipticity and scenario for increased electron temperature in mirror machines2004Inngår i: Annual Meeting Research Union Swedish Association - RUSA, Studsvik, Sweden, 20-21 April, 2004Konferansepaper (Annet vitenskapelig)
  • 1784.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Savenko, Natalia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. Avdelningen för elektricitetslära och åskforskning.
    Theory of the straight field line mirror2005Inngår i: 32nd EPS Conference on Plasma Physics, 27 June - 1 July, Tarragona, Spain, 2005, s. Vol. 29 C, P-4.069Konferansepaper (Fagfellevurdert)
  • 1785.
    Ågren, Olov
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. elektricitetslära och åskforskning.
    Savenko, Natalja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära. elektricitetslära och åskforskning.
    Reply to comment by Dr Kotelnikov on2006Inngår i: Physics of Plasmas, Vol. 13, s. 124701-Artikkel i tidsskrift (Fagfellevurdert)
  • 1786.
    Åhgren, Malin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Framtidens elnät: En studie över hur olika framtidsscenarionpåverkar elnätskundens ekonomiska förutsättningar2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In association with Sweco Energuide, two different futurescenarios have been developed regarding how the power gridcustomers might use the power grid in 10 years. In the firstscenario, scenario high load, the customers will not use anyenergy storage or load management. As a result their power demandwill increase drastically. If the customers act as in the secondscenario, scenario low load, they will see the potential ininvesting in energy storage and load management to reduce theirpower grid costs. The study has explored the economic incentivesto invest in scenario low load, which factors will affect thechoice of scenario low load and what will push the customers tochoose between the scenarios.The purpose of the study has been fulfilled by hearing theexperts’ prognosis for the future and doing a net present valueanalysis to examine the economic incentives. Power grid companieswill charge the maximal power output and if the customer do notmake any active choices it will lead to higher electrical costs.The economic incentives are mainly dependent on which choices thecustomers make regarding how the car is charged. By choosing lowercharge power and by consuming the power during time periods withlower electrical costs the customer can find incentives to act asscenario low load. If there is a time dynamic tariff theincentives increases. Even though the battery technologies andload management techniques are constantly developed the costs aretoo high and reduce the profitability of scenario low load.

    Fulltekst (pdf)
    fulltext
  • 1787.
    Åslund, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Requirements on the backup discharge system of spillways2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Hydropower is the largest producer of

    renewable electricity in Sweden with a

    yearly mean production of 65TWh. A key

    aspect of hydropower is its’ ability to

    store energy in dams and therefore being

    able to adjust the production to the

    energy consumption. Since each river

    system in Sweden is different each dam

    is unique. The focus on dam safety

    issues has increased in Sweden during

    the last 15 years. SMHI has created more

    accurate flow models and new dam safety

    ideas have been obtained though

    international collaboration. The RIDAS

    guidelines for dam safety govern the

    hydro power companies’ dam safety work.

    Dams are rated after the consequence of

    a dam breach. The consequence class of a

    dam puts demands on the backup system. A

    consequence class 1 dam is to be

    dimensioned to withstand a 10000 year

    flow and is also required to have a

    backup system installed. In accordance

    to the demands set by RIDAS, Fortum have

    decided to do dam investigations called

    FDU on a regular basis. Due to a focus

    on dam safety Fortum are conducting dam

    safety increasing projects on several of

    their dams. Backup systems can be

    designed in many different ways and must

    be customized to fit the properties of

    the dam. By analyzing the river system,

    how the dam is designed and what the

    surroundings look like conclusions about

    what is needed in terms of backup system

    can be drawn.

    Fulltekst (pdf)
    fulltext
  • 1788.
    Åström, Karl
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Productivity Improvements in Assembly: Vertical synchronous generators; Stator Core and Rotor Rim2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Fulltekst (pdf)
    Thesis_Productivity improvements in assembly_Vertical Synchronous Generators
  • 1789.
    Öberg, Jonas
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Lindeberg, Oscar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Energikartläggning: av LKAB Logistik, samt energieffektiviseringsåtgärder2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis concerns an energy audit of LKAB Logistics. According toswedish law a company the size of LKAB are required to make an energyaudit every four year. LKAB Logistics mainly transports refined ironore products between mines and harbours along the train track"Malmbanan". They also store iron ore products and load boats in theharbours in Narvik and Luleå. These kinds of operations have a highdemand for energy. This demand is met mostly with electricity.However, oil, gas, diesel and district heating are also consumed tomeet the energy demand. In total LKAB Logistics consume around 191GWh, where roughly 75% is of electricity. With such high demand,savings around 1-2% makes a significant difference, and there areopportunities and incentives to improve energy efficiency.Implementing staff that are responsible for energy work, makinginvestments in new electrical motors and more energy-efficient windowsare a few examples. Higher priority on energy saving and continuedprogress for a more efficient work place will most likely benefit thecompany's environmental goals and economy.

    Fulltekst (pdf)
    fulltext
  • 1790.
    Ögren, Jim
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Simulation of a Self-bearing Cone-shaped Lorentz-type Electrical Machine2013Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Self-bearing machines for kinetic energy storage have the advantage of integrating the magnetic bearing in the stator/rotor configuration, which reduces the number of mechanical components needed compared with using separated active magnetic bearings. This master's thesis focus on building a MATLAB/Simulink simulation model for a self-bearing cone-shaped Lorenz-type electrical machine. The concept has already been verified analytically but no dynamic simulations have been made. The system was modeled as a negative feedback system with PID controllers to balance the rotor. Disturbances as signal noise, external forces and torques were added to the system to estimate system robustness. Simulations showed stability and promising dynamics, the next step would be to build a prototype. 

    Fulltekst (pdf)
    Simulation of a Self-bearing Cone-shaped Lorentz-type Electrical Machine
  • 1791.
    Örarbäck, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Självkörande fordon: En analys av energianvändning och kapacitet2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Self-driving cars are soon to become a reality to the commercial market. A self-driving car does not have a human operator, which enables some interesting characteristics. The main benefits are considered to be:

    • The number of accidents and traffic jams should be reduced.
    • Enhanced comfort.
    • Energy usage could be decreased while capacity could be increased.

    This study concerns the causes for improved energy efficiency. The reason for improved energy efficiency is mainly because of the variation in terms of acceleration, braking and distance holding are reduced. The vehicles are more intelligent and can work together as a unity. There are reasons to believe that self-driving cars will first operate in highway conditions. The study has therefore tried to estimate what the potential benefits could be in terms of energy usage and capacity when comparing two sets of traffic flows in such an environment. One set of traffic flow was symbolized by self-driving cars, and one set was composed by conventional vehicles. With the settings and conditions defining the simulations in this study one can expect positive effects in both in energy usage and capacity with a traffic flow symbolized by self-driving cars. When comparing the two sets, with an increasing traffic flow from non-congestion up to congestion, the results showed energy savings around 10 percent with self-driving cars. 

    Fulltekst (pdf)
    fulltext
  • 1792.
    Örnborg, Bob
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Bussningstillverkning med industrirobot: till vågkraftverk2014Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Då värdens yta är upp till 70 % täckt av vatten finns det stor potential för energigenerering av vattnets vågrörelser. Uppsala universitet har beställt denna rapport då de har en prototyp av vågkraftgenerator för att kunna ta tillvara denna energitillgång. Då den produktionsmetod som beställaren idag använder är både dyr och tidskrävande behöver industrirobotar introduceras i produktionen.

    Rapporten kommer att undersöka om möjlighet finns att producera det två gummibaserade ändstopp som linjärgeneratorn behöver. De produktionsmetoderna som kommer att behandlas är stansning, vattenskärning och fräsning av EPDM Duro 65. Då kostnaderna har hög prioritering är den industrirobot som produktionsmetoden ska utföras med av en 23 år gammal modell.

    Rapporten kommer även att presentera ett färdigt förslag för att direkt kunna implementeras in i produktionen. Detta om resultatet uppnår de specifikationer som produktionsmetoden måste uppfylla för att kunna implementeras. Den kommer även att göra en ekonomisk beräkning för att se om projektet kan ha ett ekonomiskt intresse för beställaren. Rapporten kommer slutligen att ge förslag för fortsatta studier.

    Fulltekst (pdf)
    Bussningstillverkning med industrirobot
  • 1793.
    Örnkloo, Johannes
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Comparison between active and passive rectification for different types of permanent magnet synchronous machines2018Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    When using an intermittent source of energy such as wind power together with a synchronous machine a frequency converter system is needed to decouple the generator from the grid, due to the fluctuations in wind speed resulting in fluctuating electrical frequency. The aim of this master's thesis is to investigate how different types of rectification methods affect permanent magnet synchronous machines of different saliency ratios. A literature study was carried out to review the research within the area and to acquire the necessary knowledge to carry out the work. Two simulation models were created that include a permanent magnet synchronous generator driven by a wind turbine and connected to the grid via a frequency converter, where one model utilizes active rectification and one utilizes passive rectification. The simulation models were verified by carrying out an experiment on a similar setup, which showed that the simulation results coincide well with the results of the experiment. The results of the simulation study were then used to compare the rectification systems as well as investigate the affect that rotor saliency has on the system. It was shown that the active rectification provided a higher efficiency than the passive rectification system, however the saliency of the rotor had little effect on the system

    Fulltekst (pdf)
    fulltext
  • 1794.
    Örnkloo, Johannes
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Comparison between active and passive rectification for different types of permanent magnet synchronous machines2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    When using an intermittent source of energy such as wind power together with a synchronous machine a frequency converter system is needed to decouple the generator from the grid, due to the fluctuations in wind speed resulting in fluctuating electrical frequency. The aim of this master's thesis is to investigate how different types of rectification methods affect permanent magnet synchronous machines of different saliency ratios. A literature study was carried out to review the research within the area and to acquire the necessary knowledge to carry out the work. Two simulation models were created that include a permanent magnet synchronous generator driven by a wind turbine and connected to the grid via a frequency converter, where one model utilizes active rectification and one utilizes passive rectification. The simulation models were verified by carrying out an experiment on a similar setup, which showed that the simulation results coincide well with the results of the experiment. The results of the simulation study were then used to compare the rectification systems as well as investigate the affect that rotor saliency has on the system. It was shown that the active rectification provided a higher efficiency than the passive rectification system, however the saliency of the rotor had little effect on the system.

    Fulltekst (pdf)
    fulltext
  • 1795.
    Örnkloo, Matilda
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Compensating Unbalances in Synchronous Railway Traction Systems with Railway Power Conditioners2016Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    The electrified railway presents significant challenges for the electrical grid. This is due to the characteristics of the constructed railway system. Trains are single-phase loads, fed by two adjacent phases from the grid. Feeding phases will change continuously at every substation. This load characteristic will lead to unbalances and poor power quality in the grid. The poor power quality is caused by the unbalance in currents, voltage drops along the line, and induced harmonics from power electronic devices used in traction.

     

    To decrease the impact of the railway traction system in the public grid, Static Var Compensators (SVCs) and Static Synchronous Compensators (STATCOMs) have been implemented. These installations offer voltage control, maintain balance and mitigate harmonics. This thesis investigates other power electronic technologies to improve the power quality in the grid for the 50 Hz railway traction system.

    Fulltekst (pdf)
    fulltext
  • 1796.
    Österberg, David
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Multi-Body Unsteady Aerodynamics in 2D Applied to aVertical-Axis Wind Turbine Using a Vortex Method2010Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Vertical axis wind turbines (VAWT) have many advantages over traditional Horizontalaxis wind turbines (HAWT).One of the more severe problem of VAWTs are the complicated aerodynamicbehavior inherent in the concept. Incontrast to HAWTs the blades experience varying angle of attack during its orbitalmotion. The unsteady flowleads to unsteady loads, and hence, to increased risk for problems with fatigue.A tool for aerodynamic analysis of vertical axis wind turbines has been developed.The model, a Discrete vortex method, relies on conformal maps to simplify the taskto finding the flowaround cylinders. After the simplified problem has been solved with Kutta condition,using the Fast Fouriertransform, the solution is transformed back to the original geometry yielding the flowabout the turbine.The program can be used for quick predictions of the aerodynamic blade loads fordifferent turbines allowing the method to be validated by comparing the predictionsto experimental data from realvertical axis wind turbines. The agreement with experiment is good.

    Fulltekst (pdf)
    FULLTEXT01
  • 1797.
    Östergård, Rickard
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Flywheel energy storage: a conceptucal study2011Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master thesis was provided by ABB Cooperate Research in Västerås. This study has two major purposes: (1) to identify the characteristics of a flywheel energy storage system (FESS), (2) take the first steps in the development of a simulation model of a FESS.

    For the first part of this master thesis a literature reviews was conducted with focus on energy storage technologies in general and FESS in particular. The model was developed in the simulation environment PSCAD/EMTDC; with the main purpose to provide working model for future studies of the electrical dynamics of a flywheel energy storage system.

    The main conclusion of the literature review was that FESS is a promising energy storage solution; up to multiple megawatt scale. However, few large scale installations have so far been built and it is not a mature technology. Therefore further research and development is needed in multiple areas, including high strength composite materials, magnetic bearings and electrical machines. The model was implemented with the necessary control system and tested in a simulation case showing the operational characteristics. 

    Fulltekst (pdf)
    fulltext
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