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Wedberg, Rolf
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Publications (10 of 12) Show all publications
Ziemann, V., Wedberg, R., Peterson, T. & Wirén, A. (2018). Earth-field Compensation Coils for the Vertical Cryostat in FREIA.
Open this publication in new window or tab >>Earth-field Compensation Coils for the Vertical Cryostat in FREIA
2018 (English)Report (Other academic)
Abstract [en]

We describe the design and construction of coils to compensate the Earth magnetic field in the vertical cryostat in FREIA.

Publisher
p. 27
Series
FREIA Report ; 2018/01
National Category
Accelerator Physics and Instrumentation
Research subject
Physics
Identifiers
urn:nbn:se:uu:diva-346574 (URN)
Available from: 2018-03-19 Created: 2018-03-19 Last updated: 2018-03-21Bibliographically approved
Jobs, M., Wedberg, R. & Gajewski, K. (2017). DB Science 400 kW RF Station Site Acceptance Test.
Open this publication in new window or tab >>DB Science 400 kW RF Station Site Acceptance Test
2017 (English)Report (Other (popular science, discussion, etc.))
Abstract [en]

The manufactured and delivered DB-Science 400 kW RF station was tested on site at FREIA during 2016. The station can successfully deliver continuous pulse-trains with a power-level up to 400 kW, however during most of the on-site measurements and testing the total combiner output power was limited to 360 kW due to unusually high G2 currents measured in one of the spare TH595 tetrode tubes used in the station. Each of the stations 200 kW tetrode based amplifier sections were mounted with TH595 tetrode tubes from Thales and tuned for optimal performance. The gain of the tetrode amplifiers were roughly 15 dB with some variation between the two amplifier sections and the overall gain was approximately 74 dB maximum. Amplitude and phase pulse variations were within the specified levels.

Series
FREIA Report ; 2017/01
Keywords
FREIA, ESS, RF, High Power, Tetrode, Amplifier, Test, Evaluation, Prototype
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-313316 (URN)
Available from: 2017-01-19 Created: 2017-01-19 Last updated: 2017-01-23Bibliographically approved
Bhattacharyya, A., Dancila, D., Ekelöf, T., Eriksson, J., Fransson, K., Gajewski, K., . . . Ziemann, V. (2015). ESS RF Source and Spoke Cavity Test Plan.
Open this publication in new window or tab >>ESS RF Source and Spoke Cavity Test Plan
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2015 (English)Report (Other academic)
Abstract [en]

This report describes the test plan for the first high power RF source, ESS prototype double spoke cavity and ESS prototype cryomodule at the FREIA Laboratory.

Publisher
p. 13
Series
FREIA Report ; 2015/01
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-246774 (URN)
Available from: 2015-03-10 Created: 2015-03-10 Last updated: 2017-01-25Bibliographically approved
Jobs, M., Wedberg, R. & Gajewski, K. (2015). Itelco-Electrosys 400 kW RF Station Site Acceptance Test. Uppsala: Uppsala University, Department of Physics and Astronomy
Open this publication in new window or tab >>Itelco-Electrosys 400 kW RF Station Site Acceptance Test
2015 (English)Report (Other (popular science, discussion, etc.))
Abstract [en]

The manufactured and delivered Itelco-Electrosys 400 kW RF station was tested on site at FREIA, in Uppsala August 31 through September 4 2015. The station could successfully deliver continuous pulsetrains with a power-level up to 400 kW. Each of the stations 200 kW tetrode based amplifier sections were mounted with TH-595 tetrode tubes from Thales and tuned for optimal performance. The gain of the tetrode amplifiers were roughly 15 dB with some variation between the two amplifier sections andthe overall gain was approximately 85 dB maximum.Some droop and phase distortion on the combined output pulse was measured caused primarily by a limited response time of the screen-grid power supply.

Place, publisher, year, edition, pages
Uppsala: Uppsala University, Department of Physics and Astronomy, 2015. p. 35
Series
FREIA Report ; 2015/07
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-263018 (URN)
Available from: 2015-09-24 Created: 2015-09-24 Last updated: 2015-10-05Bibliographically approved
Olvegård, M., Bhattacharyya, A., Dancila, D., Ekelöf, T., Eriksson, J., Fransson, K., . . . Yogi, R. (2015). PROGRESS AT THE FREIA LABORATORY. In: Proceedings of IPAC'15: . Paper presented at IPAC'15, the sixth International Particle Accelerator Conference, Virginia, USA, May 3-8, 2015. JACoW: The Joint Accelerator Conferences Website
Open this publication in new window or tab >>PROGRESS AT THE FREIA LABORATORY
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2015 (English)In: Proceedings of IPAC'15, JACoW: The Joint Accelerator Conferences Website , 2015Conference paper, Published paper (Refereed)
Abstract [en]

The FREIA Facility for Research Instrumentation and Accelerator Development at Uppsala University, Sweden, has reached the stage where the testing of superconducting cavities for the European Spallation Source (ESS) is starting. The new helium liquefaction plant has been commissioned and now supplies a custom-made, versatile horizontal cryostat, HNOSS, with liquid helium at up to 140 l/h. The cryostat has been designed and built to house up to two accelerating cavities, or, later on, other superconducting equipment such as magnets or crab cavities. A prototype cavity for the spoke section of the ESS linac will arrive mid 2015 for high-power testing in the horizontal cryostat. Two tetrode-based commercial RF power stations will deliver 400 kW peak power each, at 352 MHz, to the cavity through an RF distribution line developed at FREIA. In addition, significant progress has been made with in-house development of solid state amplifier modules and powercombiners for future use in particle accelerators. We report here on these and other ongoing activities at the FREIA laboratory.

Place, publisher, year, edition, pages
JACoW: The Joint Accelerator Conferences Website, 2015
National Category
Accelerator Physics and Instrumentation Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-263956 (URN)
Conference
IPAC'15, the sixth International Particle Accelerator Conference, Virginia, USA, May 3-8, 2015
Available from: 2015-10-05 Created: 2015-10-05 Last updated: 2017-01-25Bibliographically approved
Dancila, D., Eriksson, A., Haapala, L., Goryashko, V., Rydberg, A., Wedberg, R., . . . Ziemann, V. (2014). Solid-state amplifier development at FREIA. In: : . Paper presented at IPAC 2014.
Open this publication in new window or tab >>Solid-state amplifier development at FREIA
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2014 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-220014 (URN)
Conference
IPAC 2014
Available from: 2014-03-10 Created: 2014-03-10 Last updated: 2017-01-25
Wedberg, R., Yogi, R. A., Goryashko, V., Santiago-Kern, R., Hermansson, L., Lofnes, T., . . . Ruber, R. (2012). Power Supplies for Tetrode High Power Amplfiers at FREIA: ESS TDR Contribution. Uppsala: Department of Physics and Astronomy, Uppsala University
Open this publication in new window or tab >>Power Supplies for Tetrode High Power Amplfiers at FREIA: ESS TDR Contribution
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2012 (English)Report (Other academic)
Abstract [en]

This paper select the topology of the power supplies to the RF power amplifier to one spoke cavity to be tested at FREIA Uppsala University.The power supplies are thought to fulfill the requirements of ESS in Lund.

The amplifiers pulsed operation will have a strong impact of the choice of topology. The RF amplifier will have two tetrodes in the final stage.

The anode power supply is studied for different topologies and number of anodes to supply.

Storing the energy for pulse current to the anodes at high voltage or at low voltage is considered.

The short circuit protection can be with a crowbar or a series switch. The series switch is selected for reasons of short interrupts in case of temporary short circuits.

The grid and filament supplies are thought to be standard of the shelf power supplies.

Cost estimate and comments on maintenance in the end of the paper.

Place, publisher, year, edition, pages
Uppsala: Department of Physics and Astronomy, Uppsala University, 2012. p. 6
Series
FREIA Report ; 2012/02
Keywords
Tetrode, FREIA, Power Supply, High Power RF Amplifier
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-182119 (URN)
Available from: 2012-10-05 Created: 2012-10-03 Last updated: 2017-01-25Bibliographically approved
Goryashko, V., Dancila, D., Ekelöf, T., Gajewski, K., Hermansson, L., Johansson, N., . . . Ziemann, V. (2012). Proposal for Design and Test of a 352 MHz Spoke RF Source. Uppsala: Department of Physics and Astronomy, Uppsala University
Open this publication in new window or tab >>Proposal for Design and Test of a 352 MHz Spoke RF Source
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2012 (English)Report (Other academic)
Abstract [en]

More than a dozen of spoke resonators prototypes (SSR, DSR, TSR) have been constructed and tested worldwide. None have accelerated beam until now and the ESS LINAC will be the first accelerator to operate with spoke cavities. Experience with other types of superconducting cavities indicates that high-power test is vital for reliable operation of the cavity in an accelerator. Although characteristics of a bare cavity can be obtained in a low-power test some important features of a `dressed' cavity like the electroacoustic stability and tuning system can be studied only in a high-power test stand. The ESS LINAC is a pulsed machine and the Lorentz detuning originating from the electromagnetic pressure on the cavity walls is expected to be strong. The Lorentz force along with the cavity sensitivity to mechanical excitations at some resonant frequencies may lead to self-sustained mechanical vibrations which make cavity operation dicult. Practical experience shows that increasing the boundary stiness will decrease the static Lorentz force detuning but not necessarily the dynamic one. Therefore, the FREIA group at Uppsala University is building a high-power test stand able to study performance of the ESS spoke cavity at high power. The RF test stand will be able to drive the cavity not only in the self-excitation mode but also with closed RF loop and fixed frequency. The later technique will be used to reproduce the shape of the cavity voltage pulse as it is expected to be in the cavity operating in the ESS LINAC such that the cavity tuning compensation system will be tested under realistic conditions.

Place, publisher, year, edition, pages
Uppsala: Department of Physics and Astronomy, Uppsala University, 2012. p. 29
Series
FREIA Report ; 2012/04
National Category
Accelerator Physics and Instrumentation Engineering and Technology
Research subject
Engineering Science with specialization in Advanced Instrumentation and Measurements; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-186802 (URN)
Projects
FREIA
Available from: 2012-11-30 Created: 2012-11-29 Last updated: 2017-01-25Bibliographically approved
Yogi, R., Wedberg, R., Goryashko, V., Santiago-Kern, R., Hermansson, L., Lofnes, T., . . . Ruber, R. (2012). Selection of RF Power Source and Distribution Scheme at 352 MHz for Spoke Cavities at ESS and FREIA. Uppsala: Uppsala universitet
Open this publication in new window or tab >>Selection of RF Power Source and Distribution Scheme at 352 MHz for Spoke Cavities at ESS and FREIA
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2012 (English)Report (Other academic)
Abstract [en]

The report describes selection of RF power source and distribution scheme for spoke cavities at ESS and FREIA.  The European Spallation Source (ESS) is the world’s most powerful neutron source, which contain 36 superconducting spoke cavities at 352MHz and provide power of 0.5MW to the beam. The baseline for the RF system is a point-to-point generation and distribution  from a single source to a single accelerating cavity.The RF system that has to generate this power and distribute it to the accelerating cavities, is a main resource driver for linear accelerators in form of investment, operation and maintenance. Therefore the technical alternatives are compared to minimize capital and running cost of the accelerator, without compromising its reliability. At 352 MHz and 350 kW RF power output, tetrode amplifiers are selected because of their advantages of being cheap, reliable, simple and efficient as compared to the other RF power amplifiers. The tetrodes, due to their low gain, need a pre-driver. The solid state amplifier technology is selected as a pre-driver due to its simplicity, reliability and efficiency. Half height aluminum WR2300 wave guides shall be used for RF distribution. This solution makes it possible to discard the circulator from the RF distribution chain, thus improving system efficiency.

Place, publisher, year, edition, pages
Uppsala: Uppsala universitet, 2012. p. 13
Series
FREIA Report ; 2012/01
Keywords
Accelerator, RF power, RF amplifier, Spoke cavity, RF distribution, ESS, FREIA
National Category
Accelerator Physics and Instrumentation Engineering and Technology
Research subject
Physics; Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-174458 (URN)
Available from: 2012-05-21 Created: 2012-05-16 Last updated: 2017-01-25Bibliographically approved
Ruber, R., Ekelöf, T., Yogi, R., Dancila, D., Gajewski, K., Goryashko, V., . . . Ziemann, V. (2012). Tests of the Spoke Cavity RF Source and Cryomodules in Uppsala: ESS TDR Contribution. Uppsala: Department of Physics and Astronomy, Uppsala University
Open this publication in new window or tab >>Tests of the Spoke Cavity RF Source and Cryomodules in Uppsala: ESS TDR Contribution
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2012 (English)Report (Other academic)
Place, publisher, year, edition, pages
Uppsala: Department of Physics and Astronomy, Uppsala University, 2012. p. 9
Series
FREIA Report ; 2012/03
Keywords
spoke cavity, RF source, cryomodule, cryogenics, test stand
National Category
Accelerator Physics and Instrumentation Engineering and Technology
Research subject
Engineering Science with specialization in Electronics
Identifiers
urn:nbn:se:uu:diva-182211 (URN)
Available from: 2012-10-05 Created: 2012-10-05 Last updated: 2017-01-25Bibliographically approved
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