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Ruber, Roger
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Publications (10 of 60) 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
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
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: 2018-09-26Bibliographically 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
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
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
Dancila, D., Hoang Duc, L., Jobs, M., Holmberg, M., Hjort, A., Rydberg, A. & Ruber, R. (2017). A compact 10 kW solid-state RF power amplifier at 352 MHz. In: : . Paper presented at 8th International Particle Accelerator Conference 14–19 May 2017, Copenhagen, Denmark (IPAC17).
Open this publication in new window or tab >>A compact 10 kW solid-state RF power amplifier at 352 MHz
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2017 (English)Conference paper, Published paper (Refereed)
Series
Journal of Physics: Conference Series, E-ISSN 1742-6596 ; 874
National Category
Communication Systems
Research subject
Engineering Science with specialization in Microwave Technology
Identifiers
urn:nbn:se:uu:diva-336076 (URN)
Conference
8th International Particle Accelerator Conference 14–19 May 2017, Copenhagen, Denmark (IPAC17)
Projects
ESS
Available from: 2017-12-12 Created: 2017-12-12 Last updated: 2017-12-14Bibliographically approved
Dancila, D., Hoang Duc, L., Jobs, M., Holmberg, M., Hjort, A., Rydberg, A. & Ruber, R. (2017). A compact 10 kW solid-state RF power amplifier at 352 MHz. Paper presented at 8th International Particle Accelerator Conference 14–19 May 2017, Copenhagen, Denmark. Journal of Physics, Conference Series, 874, Article ID 012093.
Open this publication in new window or tab >>A compact 10 kW solid-state RF power amplifier at 352 MHz
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2017 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 874, article id 012093Article in journal (Refereed) Published
Abstract [en]

A compact 10 kW RF power amplifier at 352 MHz was developed at FREIA for the European Spallation Source, ESS. The specifications of ESS for the conception of amplifiers are related to its pulsed operation: 3.5 ms pulse length and a duty cycle of 5%. The realized amplifier is composed of eight kilowatt level modules, combined using a planar Gysel 8-way combiner. The combiner has a low insertion loss of only 0.2 dB, measured at 10 kW peak power. Each module is built around a commercially available LDMOS transistor in a single-ended architecture. During the final tests, a total output peak power of 10.5 kW was measured.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-334907 (URN)10.1088/1742-6596/874/1/012093 (DOI)000411396700093 ()
Conference
8th International Particle Accelerator Conference 14–19 May 2017, Copenhagen, Denmark
Projects
ESS
Available from: 2017-11-29 Created: 2017-11-29 Last updated: 2018-03-20Bibliographically approved
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