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Goryashko, Vitaliy
Alternative names
Publications (10 of 39) Show all publications
Mak, A., Salén, P., Goryashko, V. & Clarke, J. (2019). Science Requirements and Performance Specification forthe CompactLight X-Ray Free-Electron Laser.
Open this publication in new window or tab >>Science Requirements and Performance Specification forthe CompactLight X-Ray Free-Electron Laser
2019 (English)Report (Other academic)
Abstract [en]

CompactLight is a consortium funded by the European Union through the Horizon 2020 Research and Innovation Programme under Grant Agreement No. 777431.  This report summarizes science requirements and performance specification for the CompactLight x-ray free-electron laser. 

Publisher
p. 18
Series
FREIA Report ; 2019/01
National Category
Accelerator Physics and Instrumentation
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-374175 (URN)
Funder
EU, Horizon 2020, 777431
Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2019-01-18Bibliographically approved
Goryashko, V., Jobs, M., Hoang, L., Eriksson, J. & Ruber, R. (2018). 12-Way 100 kW Reentrant Cavity-Based Power Combiner With Doorknob Couplers. IEEE Microwave and Wireless Components Letters, 28(2), 111-113
Open this publication in new window or tab >>12-Way 100 kW Reentrant Cavity-Based Power Combiner With Doorknob Couplers
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2018 (English)In: IEEE Microwave and Wireless Components Letters, ISSN 1531-1309, E-ISSN 1558-1764, Vol. 28, no 2, p. 111-113Article in journal (Refereed) Published
Abstract [en]

We present radio frequency (RF) and thermal characterization of a compact 12-way power combiner designed for operation at 352 MHz at a power level of 100 kW with 5% duty factor. The combiner is based on a reentrant cavity with 12 input doorknob couplers and one output coupler that is integrated with the post of the cavity and forms doorknob type geometry. We introduce convenient design formulas that allow easy identification of a suitable parameter space, which is then refined with numerical simulations. Low-power RF measurements of a prototype show 0.2% insertion loss and a relative rms amplitude imbalance between the ports of 0.1% and phase imbalance of 0.036 degrees rms. The matching is better than -25 dB over a 3-dB bandwidth around the design frequency. We also tested the combiner up to 200 kW and found the RF loss to be comparable to that of the low-power measurement. In a long test run at 100 kW with 5% duty factor, the combiner temperature stabilized at 10 degrees above ambient.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
High-power handling capability, high-power radio frequency (RF) measurements, power combiner, thermal study
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-349845 (URN)10.1109/LMWC.2017.2780619 (DOI)000425173500007 ()
Available from: 2018-05-03 Created: 2018-05-03 Last updated: 2018-05-03Bibliographically approved
Shamuilov, G., Mak, A., Salén, P. & Goryashko, V. (2018). Analytical model of waveform-controlled single-cycle light pulses from an undulator. Optics Letters, 43(4), 819-822
Open this publication in new window or tab >>Analytical model of waveform-controlled single-cycle light pulses from an undulator
2018 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 43, no 4, p. 819-822Article in journal (Refereed) Published
Abstract [en]

This Letter builds upon a recent concept [Phys. Rev. Lett. 113, 104801 (2014)] for producing ultrashort optical pulses through the coherent radiation of electrons in an undulator. Each pulse contains only a single oscillation cycle, and has a controlled waveform (and hence a stable carrier-envelope phase). While the concept had been demonstrated numerically, this Letter provides an analytical model for the radiation mechanism, thereby revealing three key observations: (i) the correlation between the waveforms of the optical and undulator fields; (ii) the free-space dispersion of transversely confined light; and (iii) the dependence of the optical pulse shape on the undulator field strength.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2018
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-349360 (URN)10.1364/OL.43.000819 (DOI)000425123700049 ()29444002 (PubMedID)
Funder
Swedish Research Council, 2016-04593
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-04-26Bibliographically approved
Shamuilov, G., Mak, A., Pepitone, K. & Goryashko, V. (2018). Child-Langmuir law for photoinjectors. Applied Physics Letters, 113(20), Article ID 204103.
Open this publication in new window or tab >>Child-Langmuir law for photoinjectors
2018 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 113, no 20, article id 204103Article in journal (Refereed) Published
Abstract [en]

The space-charge field at the cathode limits the current density extracted from particle sources such as photoinjectors. For a long time, the maximum current has been estimated by using the classical Child-Langmuir law, which is derived with an assumption inconsistent with the conditions of modern laser-driven electron guns. Here, we introduce a theoretical model that accurately accounts for space-charge effects in transversely confined particle beams emerging from photocathodes. The model enables us to (i) determine the maximum current density extractable from the photocathode for an arbitrary cathode radius, (ii) reveal its dependence on the transverse profile of the particle beam, and (iii) predict its upper limit for structured beams such as the ones produced by surface-plasmon resonance-enhanced photocathodes.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-371542 (URN)10.1063/1.5063888 (DOI)000450279900035 ()
Funder
Swedish Research Council, 2016-04593
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Opanasenko, A. M. & Goryashko, V. (2018). Multislice Model Of Electron Bunch For Study Of Ballistic Bunching Of Low Emittance Beams. Problems Of Atomic Science And Technology (3), 73-80
Open this publication in new window or tab >>Multislice Model Of Electron Bunch For Study Of Ballistic Bunching Of Low Emittance Beams
2018 (English)In: Problems Of Atomic Science And Technology, ISSN 1562-6016, no 3, p. 73-80Article in journal (Refereed) Published
Abstract [en]

At ballistic bunching of an electron beam the transverse distribution of space-charge field varies along a bunch greatly. It can lead to emittance growth unless to provide its compensation. To study this problem, a multislice model of a bunch of relativistic charged particles that needs no smallness of energy spread between slices are developed. This removes the limit on the value of the RF field that modulates the slices by velocity before their injection into a drift space. The longitudinal dynamics of each slice is determined by its interaction with the field of the entire bunch averaged over the slice. Transverse beam characteristics are found from a differential equation for root-mean-square envelope of a beam.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-372426 (URN)000451570000016 ()
Funder
Swedish Research Council
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Hoang Duc, L., Bhattacharyya, A., Goryashko, V., Ruber, R., Olsson, J. & Dancila, D. (2018). Time Domain Characterization of High Power Solid State Amplifiers for the Next Generation Linear Accelerators. Microwave and optical technology letters (Print), 60(1), 163-171
Open this publication in new window or tab >>Time Domain Characterization of High Power Solid State Amplifiers for the Next Generation Linear Accelerators
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2018 (English)In: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 60, no 1, p. 163-171Article in journal (Refereed) Published
Abstract [en]

This paper presents the time domain characterization of high power pulsed solid state amplifiers to be used forlinear accelerator applications. The study comprises nonlinear circuit envelope simulations and time domainenvelope measurements. Measurements and simulations are performed under the pulsed conditions (3.5 mspulse width, 5% duty cycle) specific to the European Spallation Source (ESS) high intensity proton accelerator.We measure the characteristics of pulsed LDMOS based power amplifiers such as: pulse droop along the pulse,efficiency, average envelope pulse amplitude and phase, pulse drain current waveform, pulse drain voltagewaveform, etc. A comparison between the measured results and the simulated results is also presented. Inaddition to the pulse profile characterization, the pulse to pulse (P2P) stability of the presented solid state poweramplifier (SSPA) is investigated as variations of amplitude and phase. The P2P stability simulations areintroduced as a combination of the Monte-Carlo simulations and the nonlinear circuit envelope simulations. Thesimulated results are used for fitting the P2P measurements to give an early insight of causes of instabilities ofthe nonlinear LDMOS models.

Keywords
accelerator, solid state amplifiers, LDMOS, nonlinear circuit envelope, time domain envelope measurements, pulse profile
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-334910 (URN)10.1002/mop.30926 (DOI)000416937700028 ()
Projects
ESS
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2018-02-28Bibliographically approved
Mak, A., Salén, P. & Goryashko, V. (2018). Undulator Considerations in the Baseline Design of the MAX IV Soft X-Ray Laser.
Open this publication in new window or tab >>Undulator Considerations in the Baseline Design of the MAX IV Soft X-Ray Laser
2018 (English)Report (Other academic)
Abstract [en]

We examine the optimal parameter space for an x-ray free-electron laser (FEL) in the operation mode of self-amplified spontaneous emission (SASE). The study focuses on FEL operation with a shorter undulator period and higher undulator strength made available through recent developments in in-vacuum, cryogenic and superconducting undulators. We survey the progress on short-period undulator technologies and compute the FEL output characteristics versus the undulator parameters. We perform the study on a case of the planned soft-x-ray FEL at the MAX IV Laboratory in Sweden. An extension of the SASE mode into the harmonic lasing self-seeded mode is also analysed.

Publisher
p. 16
Series
FREIA Report ; 2018-4
National Category
Accelerator Physics and Instrumentation
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-357900 (URN)
Funder
Swedish Research Council, 2016-04593The Royal Swedish Academy of Sciences, PH2018- 0037EU, Horizon 2020, 777431
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-22Bibliographically approved
Santiago Kern, R., Bhattacharyya, A., Gajewski, K., Goryashko, V., Hermansson, L., Jobs, M., . . . Ruber, R. (2017). Cryogenic Synopsis from the Testing of the Fully Equipped ESS’ Double Spoke Cavity Romea. Uppsala
Open this publication in new window or tab >>Cryogenic Synopsis from the Testing of the Fully Equipped ESS’ Double Spoke Cavity Romea
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2017 (English)Report (Other academic)
Place, publisher, year, edition, pages
Uppsala: , 2017. p. 29
Series
FREIA Report ; 2017/12
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-333037 (URN)
Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2017-11-09Bibliographically approved
Opanasenko, A., Mytrochenko, V., Zhaunerchyk, V. & Goryashko, V. (2017). Design study of a low-emittance high-repetition rate thermionic rf gun. PHYSICAL REVIEW ACCELERATORS AND BEAMS, 20(5), Article ID 053401.
Open this publication in new window or tab >>Design study of a low-emittance high-repetition rate thermionic rf gun
2017 (English)In: PHYSICAL REVIEW ACCELERATORS AND BEAMS, ISSN 2469-9888, Vol. 20, no 5, article id 053401Article in journal (Refereed) Published
Abstract [en]

We propose a novel gridless continuous-wave radiofrequency (rf) thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an.-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-360219 (URN)10.1103/PhysRevAccelBeams.20.053401 (DOI)000440464600002 ()
Funder
Swedish Research Council
Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2018-09-13Bibliographically approved
Li, H., Santiago-Kern, R., Jobs, M., Bhattacharyya, A., Goryashko, V., Hermansson, L., . . . Ruber, R. (2017). First High Power Test of the ESS Double Spoke Cavity. Uppsala
Open this publication in new window or tab >>First High Power Test of the ESS Double Spoke Cavity
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2017 (English)Report (Other academic)
Abstract [en]

The first double spoke cavity for ESS project was tested with high power in the HNOSS cryostat at FREIA Laboratory. This cavity is designed for 325.21MHz, a pulse mode with 14 Hz repetition rate, up to peak power of 360 kW. The qualification of the cavity package in a high power test, involved a spoke superconducting cavity, a fundamental power coupler, LLRF system and a RF station, represented an important verification before the module assembly. This report presents the test configuration, RF conditioning history and first high power performance of this cavity package.

Place, publisher, year, edition, pages
Uppsala: , 2017. p. 60
Series
FREIA Report ; 2017/10
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-335434 (URN)
Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2017-12-06Bibliographically approved
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