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Ruber, Roger
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Publications (10 of 64) Show all publications
Ruber, R., Wedberg, R., Peterson, T., Dancila, D., Hoang, L. & Eriksson, J. (2019). 400 kW RF Stations Operational Experience: Overview of the operation experience during 2018-2019 with the Itelco-Electrosys and DB Science stations at the FREIA Laboratory. Uppsala universitet
Open this publication in new window or tab >>400 kW RF Stations Operational Experience: Overview of the operation experience during 2018-2019 with the Itelco-Electrosys and DB Science stations at the FREIA Laboratory
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2019 (English)Report (Other academic)
Abstract [en]

We present the operational experience with the Itelco-Electrosys and DB Science 400 kW RF stations installed at the FREIA Laboratory. From the summer of 2018 to the summer of 2019 the stations were used for the test of the spoke cryomodule prototype for ESS. Unfortunately multiple issues with both RF stations delayed or inhibited normal operation. The Itelco-Electrosys station was out-of-operation from October 2018 to June 2019, due to multiple issues, which took a long time to understand and solve.

Place, publisher, year, edition, pages
Uppsala universitet, 2019. p. 24
Series
FREIA Report ; 2019/06
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-397292 (URN)
Available from: 2019-11-19 Created: 2019-11-19 Last updated: 2019-11-25Bibliographically approved
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., Li, H., Miyazaki, A., Gajewski, K., Hermansson, L., Fransson, K., . . . Ruber, R. (2019). Cryogenic Performance of the Spoke Prototype Cryomodule for ESS.
Open this publication in new window or tab >>Cryogenic Performance of the Spoke Prototype Cryomodule for ESS
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2019 (English)Report (Other academic)
Abstract [en]

This report gives an account of all the cryogenic tests performed on the prototype spoke cryomodule, which housed Romea (cavity 1) and Giulietta (cavity 2) with all their ancillary equipment, such as static and dynamic heat loads under different circumstances.

Publisher
p. 48
Series
FREIA Report ; 2019/05
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-397744 (URN)
Available from: 2019-11-25 Created: 2019-11-25 Last updated: 2019-11-26Bibliographically approved
Eriksson, J., Jacewicz, M. & Ruber, R. (2019). Cryosystem for DC spark experiments: Construction and acceptance tests. Uppsala University
Open this publication in new window or tab >>Cryosystem for DC spark experiments: Construction and acceptance tests
2019 (English)Report (Other academic)
Place, publisher, year, edition, pages
Uppsala University, 2019. p. 16
Series
FREIA Report ; 2019/02
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-396971 (URN)
Available from: 2019-11-12 Created: 2019-11-12 Last updated: 2019-11-18Bibliographically approved
Hoang Duc, L., Jobs, M., Lofnes, T., Ruber, R., Olsson, J. & Dancila, D. (2019). Feedback compensated 10 kW solid-state pulsed power amplifier at 352 MHz for particle accelerators. Review of Scientific Instruments, 90(10), Article ID 104707.
Open this publication in new window or tab >>Feedback compensated 10 kW solid-state pulsed power amplifier at 352 MHz for particle accelerators
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2019 (English)In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 90, no 10, article id 104707Article in journal (Refereed) Published
Abstract [en]

This paper presents the first results of an in-house developed low-level radio frequency (LLRF) system and a 10 kW solid state power amplifier (SSPA). The design approach for the SSPA is based on eight resonant single-ended kilowatt modules combined using a planar Gysel combiner. Each of the single-ended modules is based on a two-stepped impedance resonant matching, allowing for harmonic suppression, simple design for massive production, and high-performance design. A design methodology to tune SSPA modules for optimum combining efficiency is presented thoroughly in the time domain. We characterize the power droop due to capacitor banks in the time domain. In open loop of compensation, it is about 1 kW within the pulse of peak value 10 kW and a duration of 3.5 ms. This may lead to the beam instability of the accelerator as particles are not provided with the same energy during the pulse. By incorporating our LLRF system, it is demonstrated that the objective of amplitude and phase stability is satisfied, as required in the European Spallation Source proton accelerator. The presented design also offers the advantages of compact form factor, low complexity, and better performance. In closed loop compensation, the variation of amplitude (pulse droop) is measured on the order of 20 W, which is equivalent to 0.2% at 10 kW peak output power.

National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-402616 (URN)10.1063/1.5110981 (DOI)000504078300062 ()
Available from: 2020-01-17 Created: 2020-01-17 Last updated: 2020-01-17Bibliographically 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: 2019-11-21Bibliographically approved
Hoang Duc, L., Nguyen Dinh The, A., Bach Gia, D., Jobs, M., Ruber, R. & Dancila, D. (2018). A new high-power low-loss air-dielectric stripline Gysel divider/combiner for particle accelerator applications at 352 MHz. IET Control Theory & Applications (5), 264-267
Open this publication in new window or tab >>A new high-power low-loss air-dielectric stripline Gysel divider/combiner for particle accelerator applications at 352 MHz
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2018 (English)In: IET Control Theory & Applications, ISSN 1751-8644, E-ISSN 1751-8652, no 5, p. 264-267Article in journal (Refereed) Published
Abstract [en]

This study presents a new two-way Gysel combiner based on an air-dielectric stripline which allows to handle very high radio-frequency power levels with low-loss suitable for power combination in accelerator applications. The insertion loss of the combiner is 0.1 dB (2%). A thick stripline implementation allows improving the power capability in both continuous wave (CW) and pulsed operation. In addition, a mechanical tuner allows compensating for assembly and fabrication discrepancies. A methodology of designing the Gysel combiner as well as high-power measurements up to 22 kW in pulsed mode are presented. Simulations and measurements are in very good agreement.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-334913 (URN)10.1049/joe.2017.0793 (DOI)000436345200003 ()
Projects
ESS
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2019-11-21Bibliographically approved
Jobs, M., Dancila, D., Eriksson, J. & Ruber, R. (2018). An 8-1 Single-Stage 10-kW Planar Gysel Power Combiner at 352 MHz. IEEE Transactions on Components, Packaging, and Manufacturing Technology, 8(5), 851-857
Open this publication in new window or tab >>An 8-1 Single-Stage 10-kW Planar Gysel Power Combiner at 352 MHz
2018 (English)In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 8, no 5, p. 851-857Article in journal (Refereed) Published
Abstract [en]

A compact single-stage 8-1 Gysel Combiner in planar technology for operation with 352-MHz pulses with peak output power of 10 kW has been designed, manufactured, and tested. The module has 0.2-dB insertion loss when operated at nominal power, and the return loss of all ports is 20 dB or better. The module was operated using 3.3-ms pulses at 14-Hz repetition rate without any signs of degradation, thermal heating, or arcing. The new design makes use of inclusions of weakly coupled lines in the common point section of the Gysel combiner. It is possible to adjust port imbalances caused by parasitic line coupling in the system for optimum performance at a given frequency by adjusting the coupling.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018
Keywords
Gysel, power combiners, UHF devices
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-356323 (URN)10.1109/TCPMT.2018.2811710 (DOI)000431915800017 ()
Available from: 2018-07-26 Created: 2018-07-26 Last updated: 2018-07-26Bibliographically 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
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