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Gajewski, Konrad
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Publications (10 of 20) Show all publications
Li, H., Jobs, M., Santiago Kern, R., Goryashko, V. A., Hermansson, L., Bhattacharyya, A., . . . Ruber, R. (2019). Characterization of a beta=0.5 double spoke cavity with a fixed power coupler. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 927, 63-69
Open this publication in new window or tab >>Characterization of a beta=0.5 double spoke cavity with a fixed power coupler
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2019 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 927, p. 63-69Article in journal (Refereed) Published
Abstract [en]

ESS, the European Spallation Source, will adopt a single family of double spoke cavities for accelerating the beam from the normal conducting section to the first family of the elliptical superconducting cavities. It will be the first double spoke cavities in the world to be commissioned for a high power proton accelerator. The first double spoke cavity for the ESS project was tested with high power in the HNOSS cryostat at Uppsala University. A pulse-mode test stand based on a self-excited loop was used in this test. The qualification of the cavity package involves a double-spoke superconducting cavity, a fixed fundamental power coupler, tuner, a low-level radiofrequency (LLRF) system and a high-power radiofrequency (RF) station. The test represents an important verification milestone before the module assembly. This cavity had unfortunately a high dynamic loss of 12W @ 9 MV/m, where potential causes for such a high value have been studied and corresponding suggestions are listed. This paper presents the test configuration, RF conditioning history, first high power performance and experience of this cavity package.

Keywords
Double spoke cavity, High power test, Self-excited loop
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-382240 (URN)10.1016/j.nima.2019.02.003 (DOI)000462142700008 ()
Funder
EU, Horizon 2020, 730871
Available from: 2019-05-16 Created: 2019-05-16 Last updated: 2019-05-16Bibliographically approved
Santiago-Kern, R., Gajewski, K., Hermansson, L., Jobs, M., Li, H., Lofnes, T. & Ruber, R. (2018). Cryogenic Synopsis from the Testing of the Fully Equipped ESS' High Beta Cavity ESS086-P01 (Part I).
Open this publication in new window or tab >>Cryogenic Synopsis from the Testing of the Fully Equipped ESS' High Beta Cavity ESS086-P01 (Part I)
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2018 (English)Report (Other academic)
Publisher
p. 20
Series
FREIA Report ; 04
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-365758 (URN)
Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2018-11-14Bibliographically approved
Santiago-Kern, R., Gajewski, K., Hermansson, L., Jobs, M., Li, H., Lofnes, T. & Ruber, R. (2018). Cryogenic Synopsis from the Testing of the Fully Equipped ESS' High Beta Cavity ESS086-P01 (Part II).
Open this publication in new window or tab >>Cryogenic Synopsis from the Testing of the Fully Equipped ESS' High Beta Cavity ESS086-P01 (Part II)
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2018 (English)Report (Other academic)
Publisher
p. 27
Series
FREIA Report ; 06
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-365761 (URN)
Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2018-11-14Bibliographically approved
Li, H., Santiago-Kern, R., Jobs, M., Hermansson, L., Gajewski, K., Lofnes, T., . . . Ruber, R. (2018). First High Power Test of the ESS High Beta Elliptical Cavity package. Uppsala University
Open this publication in new window or tab >>First High Power Test of the ESS High Beta Elliptical Cavity package
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2018 (English)Report (Other academic)
Abstract [en]

The first high-beta elliptical cavity for ESS project was tested with high power in the HNOSS cryostat at FREIA Laboratory.  This cavity is designed for 704.42 MHz, a pulse mode with 14 Hz repetition rate, up to peak power of 1.5 MW. The qualification of the cavity package in a high power test, involved an elliptical superconducting cavity, a fundamental power coupler, cold tuning system, LLRF system and klystron system, 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 University, 2018. p. 60
Series
FREIA Report ; 2018/07
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-371627 (URN)
Available from: 2018-12-21 Created: 2018-12-21 Last updated: 2019-01-09Bibliographically 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
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
Li, H., Jobs, M., Gajewski, K., Santiago Kern, R., Hermansson, L. & Ruber, R. (2017). ESS Spoke Cavity Conditioning at FREIA. In: Proceedings of IPAC2017: . Paper presented at 8th International Particle Accelerator Conference IPAC2017, MOPVA094, Copenhagen Denmark, May 14-19, 2017. (pp. 1074-1076).
Open this publication in new window or tab >>ESS Spoke Cavity Conditioning at FREIA
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2017 (English)In: Proceedings of IPAC2017, 2017, p. 1074-1076Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

The first ESS double spoke cavity installed with RF power coupler was tested in the HNOSS cryostat at the FREIA Laboratory. Power coupler and cavity conditioning have been optimized in order to reach high efficiency and high availability by reducing the time and effort of the overall conditioning process. Meanwhile, an optimal procedure for ESS conditioning is studied. This paper presents the study result and experience of the RF conditioning procedure for the first ESS double spoke cavity.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-373262 (URN)978-3-95450-182-3 (ISBN)
Conference
8th International Particle Accelerator Conference IPAC2017, MOPVA094, Copenhagen Denmark, May 14-19, 2017.
Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-21Bibliographically 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
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
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