IPAC2011 - List of Keywords (superconducting-cavity)

Paper	Title	Other Keywords	Page
MOPC085	Quality Assessment for Industrially Produced High-Gradient Superconducting Cavities	cavity, niobium, SRF, linac	274
	F. Schlander, S. Aderhold, E. Elsen, D. Reschke, M. Wenskat DESY, Hamburg, Germany
	Funding: This work is supported by the Commission of the European Communities under the 7th Framework Programme “Construction of New Infrastructures – Preparatory Phase”, contract number 206711. A series of some 600 superconducting 1.3 GHz cavities will start being delivered to DESY by industry in early 2012. Although a considerably smaller gradient satisfies the needs for the European XFEL the electro-polished cavities (50% of the delivery) are deemed to be suitable for gradients in excess of 35 MV/m, the performance goal of the International Linear Collider (ILC). Specifically 24 cavities will be supplied without helium tank to enable further investigations. The results may serve to improve overall performance; limitations such as field emission and thermal breakdown of superconductivity ("quench") are still under investigation. For this matter the DESY ILC group has developed tools to monitor aspects of the cavity fabrication. An automated optical mapping system (OBACHT) is being commissioned and will be complemented by software for automated cavity surface feature recognition. For cold RF tests a Second Sound setup for locating the positions of the thermal breakdown is routinely used. These diagnostic tools will give guidance on post-processing cavities for best performance. The current status of these projects will be described.

MOPC086	Description and First Experience with the RF Measurement Procedure for the European XFEL SC Cavity Production	cavity, HOM, SRF, cryomodule	277
	A.A. Sulimov, Th. Buettner, A. Gössel, D. Kostin, G. Kreps, W.-D. Möller, D. Reschke, J.H. Thie, K. Twarowski DESY, Hamburg, Germany
	Cavity production for the European XFEL was recently started with first Nb sheets arriving. From this stage to the accelerating module being ready for the linac installation, many critical RF measurements are necessary. During the mechanical cavity fabrication the cavity half-cells, dumb-bells and end-groups are measured and sorted. The cavity spectrum and field profiles are measured and tuned. The HOM (Higher Oder Modes) couplers filter tuning, vertical cavity RF tests, cavity checks during the string assembly and final cavity performance measurements in the module as well as the fundamental mode and HOM RF spectra measurements complete the sequence. We present the procedures of the RF measurements and discuss the first results for the XFEL prototype modules with special attention for the cavity tuning.
	Poster MOPC086 [0.515 MB]

MOPC095	Superconducting Cavity R&D for ILC at MHI	cavity, HOM, linac, status	298
	H. Hitomi, H. Hara, F. Inoue, K. Kanaoka, K. Sennyu, T. Yanagisawa MHI, Kobe, Japan
	We have developed and manufactured some superconducting RF cavity for STF project in KEK. In recent vertical test in KEK, the MHI-#12 cavity which is one of cavities for STF phase 2 project reached ILC specification(max Eacc was about 40MV/m). So techniques for manufacturing cavity is making steady progress in MHI. To be realized ILC project, we also try to decrease the manufacturing cost by using some new techniques, for example Laser Beam Welding, deep drawing, seamless dumbbell, etc. In this meeting, we will report recent MHI's activities for ILC.

MOPC097	LLRF Control System for PKU DC-SC Photocathode Injector	controls, cavity, LLRF, SRF	304
	H. Zhang, Y.M. Li, K.X. Liu, F. Wang, B.C. Zhang PKU/IHIP, Beijing, People's Republic of China
	A 1.3 GHz 3.5 Cell LG niobium cavity is installed for the new PKU DC-SC injector as its accelerating cavity with working temperature is 2K. High amplitude and phase stability is required for the updated SRF photocathode injector. This paper describes the design of Low Level RF control system based on FPGA, including hardware and software,and the communication function is realized by Tri-State Ethernet. The system should be operated on the precision with the amplitude of ±0.1% and phase stability of ±0.1°.

MOPC102	RF and Surface Properties of Superconducting Samples	niobium, quadrupole, cavity, superconductivity	310
	T. Junginger, W. Weingarten CERN, Geneva, Switzerland T. Junginger MPI-K, Heidelberg, Germany R. Seviour Lancaster University, Lancaster, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF) The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since Rs varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. It is shown how different contributions to the surface resistance depend on temperature, applied RF magnetic field and frequency. Furthermore, measurements of the maximum RF magnetic field as a function of temperature and frequency in pulsed and CW operation are presented. The study is accompanied by measurements of the surface properties of the samples by various techniques.

MOPC128	16 kW Upgrade of the 1.3 GHz ELBE RF-system (CW) with Solid State Amplifiers	klystron, linac, rf-amplifier, cavity	379
	H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert HZDR, Dresden, Germany
	The superconducting CW- LINAC of the radiation source ELBE is in permanent operation since May 2001. In 2011 an upgrade program of ELBE is in progress to support additional applications. One part of the program is to double the RF-power per cavity to at least 16 kW. We first tested a 30 kW IOT-based amplifier (Bruker /CPI) at a cavity, later two 10 kW solid state amplifiers in parallel. The best solution found is based on 10 kW Solid State Power Amplifiers (SSPA) developed by Bruker BioSpin. The poster gives an overview on the status, the activities around this RF-upgrade project and the technical specification of the “turnkey” SSPA , designed for 10 kW, 1.3 GHz and full CW-operation.

MOPC151	Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*	cavity, controls, low-level-rf, linac	433
	M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I. Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

MOPC156	Operation Test of Distributed RF System with Circulator-less Waveguide Distribution in S1-Global Project at STF/KEK	cavity, klystron, feedback, linac	448
	T. Matsumoto, M. Akemoto, D.A. Arakawa, S. Fukuda, H. Honma, E. Kako, H. Katagiri, S. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakajima, K. Nakao, T. Shidara, T. Takenaka, Y. Yano, M. Yoshida KEK, Ibaraki, Japan
	Distributed RF System (DRFS) is one candidate for a single main linac tunnel design of International International Linear Collider (ILC). In the DRFS, more than ten 800-kW klystrons having a modulating anode are operated by a common DC power and a modulation anode modulator. Each klystron feeds its power into two superconducting cavities and its waveguide distribution system is configured without circulators. This DRFS consists of four SC cavities, two klystrons and a modulator was demonstrated in S1-Global project. The results of circulator-less operation in the DRFS will be reported.

WEPC096	Calculation of High Frequency Fields in Resonant Cavities Based on Perturbation Theory*	cavity	2235
	K. Brackebusch, H.-W. Glock, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10HRC. The knowledge of the eigenmodes of resonant accelerator cavities is essential for the determination of their performance characteristics, comprising resonant frequencies and field distributions inside the cavities. Apart from the material properties the eigenmodes of a cavity depend on its geometry. In spite of the high elaborateness during the complex fabrication process, minor deviations of the actual cavity shape from the desired one are inevitable. Moreover, especially superconducting cavities are subject to extreme operating conditions that may cause deformations of their shape. Any geometry perturbation results in a shift of the resonant frequencies and modified field distributions. In this paper, we will analyze a generalization of Slater's theorem proposed in literature. The method should allow for the calculation of resonant frequencies and field distributions of a slightly perturbed cavity by using a set of precomputed eigenmodes of the unperturbed cavity. We will evaluate the practicability of the method by applying it to cavity geometries for which the eigenmodes are analytically known, ascertain the effort of reasonable calculation results and describe its limitations.

Paper

Title

Other Keywords

Page

MOPC085

Quality Assessment for Industrially Produced High-Gradient Superconducting Cavities

cavity, niobium, SRF, linac

274

F. Schlander, S. Aderhold, E. Elsen, D. Reschke, M. Wenskat
DESY, Hamburg, Germany

Funding: This work is supported by the Commission of the European Communities under the 7th Framework Programme “Construction of New Infrastructures – Preparatory Phase”, contract number 206711.
A series of some 600 superconducting 1.3 GHz cavities will start being delivered to DESY by industry in early 2012. Although a considerably smaller gradient satisfies the needs for the European XFEL the electro-polished cavities (50% of the delivery) are deemed to be suitable for gradients in excess of 35 MV/m, the performance goal of the International Linear Collider (ILC). Specifically 24 cavities will be supplied without helium tank to enable further investigations. The results may serve to improve overall performance; limitations such as field emission and thermal breakdown of superconductivity ("quench") are still under investigation. For this matter the DESY ILC group has developed tools to monitor aspects of the cavity fabrication. An automated optical mapping system (OBACHT) is being commissioned and will be complemented by software for automated cavity surface feature recognition. For cold RF tests a Second Sound setup for locating the positions of the thermal breakdown is routinely used. These diagnostic tools will give guidance on post-processing cavities for best performance. The current status of these projects will be described.

MOPC086

Description and First Experience with the RF Measurement Procedure for the European XFEL SC Cavity Production

cavity, HOM, SRF, cryomodule

277

A.A. Sulimov, Th. Buettner, A. Gössel, D. Kostin, G. Kreps, W.-D. Möller, D. Reschke, J.H. Thie, K. Twarowski
DESY, Hamburg, Germany

Cavity production for the European XFEL was recently started with first Nb sheets arriving. From this stage to the accelerating module being ready for the linac installation, many critical RF measurements are necessary. During the mechanical cavity fabrication the cavity half-cells, dumb-bells and end-groups are measured and sorted. The cavity spectrum and field profiles are measured and tuned. The HOM (Higher Oder Modes) couplers filter tuning, vertical cavity RF tests, cavity checks during the string assembly and final cavity performance measurements in the module as well as the fundamental mode and HOM RF spectra measurements complete the sequence. We present the procedures of the RF measurements and discuss the first results for the XFEL prototype modules with special attention for the cavity tuning.

Poster MOPC086 [0.515 MB]

MOPC095

Superconducting Cavity R&D for ILC at MHI

cavity, HOM, linac, status

298

H. Hitomi, H. Hara, F. Inoue, K. Kanaoka, K. Sennyu, T. Yanagisawa
MHI, Kobe, Japan

We have developed and manufactured some superconducting RF cavity for STF project in KEK. In recent vertical test in KEK, the MHI-#12 cavity which is one of cavities for STF phase 2 project reached ILC specification(max Eacc was about 40MV/m). So techniques for manufacturing cavity is making steady progress in MHI. To be realized ILC project, we also try to decrease the manufacturing cost by using some new techniques, for example Laser Beam Welding, deep drawing, seamless dumbbell, etc. In this meeting, we will report recent MHI's activities for ILC.

MOPC097

LLRF Control System for PKU DC-SC Photocathode Injector

controls, cavity, LLRF, SRF

304

H. Zhang, Y.M. Li, K.X. Liu, F. Wang, B.C. Zhang
PKU/IHIP, Beijing, People's Republic of China

A 1.3 GHz 3.5 Cell LG niobium cavity is installed for the new PKU DC-SC injector as its accelerating cavity with working temperature is 2K. High amplitude and phase stability is required for the updated SRF photocathode injector. This paper describes the design of Low Level RF control system based on FPGA, including hardware and software,and the communication function is realized by Tri-State Ethernet. The system should be operated on the precision with the amplitude of ±0.1% and phase stability of ±0.1°.

MOPC102

RF and Surface Properties of Superconducting Samples

niobium, quadrupole, cavity, superconductivity

310

T. Junginger, W. Weingarten
CERN, Geneva, Switzerland
T. Junginger
MPI-K, Heidelberg, Germany
R. Seviour
Lancaster University, Lancaster, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF)
The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since Rs varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. It is shown how different contributions to the surface resistance depend on temperature, applied RF magnetic field and frequency. Furthermore, measurements of the maximum RF magnetic field as a function of temperature and frequency in pulsed and CW operation are presented. The study is accompanied by measurements of the surface properties of the samples by various techniques.

MOPC128

16 kW Upgrade of the 1.3 GHz ELBE RF-system (CW) with Solid State Amplifiers

klystron, linac, rf-amplifier, cavity

379

H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
HZDR, Dresden, Germany

The superconducting CW- LINAC of the radiation source ELBE is in permanent operation since May 2001. In 2011 an upgrade program of ELBE is in progress to support additional applications. One part of the program is to double the RF-power per cavity to at least 16 kW. We first tested a 30 kW IOT-based amplifier (Bruker /CPI) at a cavity, later two 10 kW solid state amplifiers in parallel. The best solution found is based on 10 kW Solid State Power Amplifiers (SSPA) developed by Bruker BioSpin. The poster gives an overview on the status, the activities around this RF-upgrade project and the technical specification of the “turnkey” SSPA , designed for 10 kW, 1.3 GHz and full CW-operation.

MOPC151

Design and Commissioning of a Multi-frequency Digital Low Level RF Control System*

cavity, controls, low-level-rf, linac

433

M. Konrad, U. Bonnes, C. Burandt, J. Conrad, R. Eichhorn, J. Enders, P.N. Nonn, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through CRC 634 and by the BMBF under 06 DA 9024 I.
Triggered by the need to control the superconducting cavities of the S-DALINAC, which have a high loaded quality factor and are thus very susceptible to microphonics, the development of a digital low level RF control system was started. The chosen design proved to be very flexible since other frequencies than the original 3 GHz may be adapted easily: The system converts the RF signal coming from the cavity (e. g. 3 GHz) down to the base band using a hardware I/Q demodulator. The base band signals are digitized by ADCs and fed into a FPGA where the control algorithm is implemented. The resulting signals are I/Q modulated before they are sent back to the cavity. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator-driven algorithm is used for the low Q normal-conducting bunching cavities. A 6 GHz RF front end allows the synchronous operation of a new 2f buncher at the S-DALINAC. Meanwhile, a 325 MHz version has been built to control a pulsed prototype test stand for the p-LINAC at FAIR. We will present the architecture of the RF control system as well as results obtained during operation.

MOPC156

Operation Test of Distributed RF System with Circulator-less Waveguide Distribution in S1-Global Project at STF/KEK

cavity, klystron, feedback, linac

448

T. Matsumoto, M. Akemoto, D.A. Arakawa, S. Fukuda, H. Honma, E. Kako, H. Katagiri, S. Matsumoto, H. Matsushita, S. Michizono, T. Miura, H. Nakajima, K. Nakao, T. Shidara, T. Takenaka, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan

Distributed RF System (DRFS) is one candidate for a single main linac tunnel design of International International Linear Collider (ILC). In the DRFS, more than ten 800-kW klystrons having a modulating anode are operated by a common DC power and a modulation anode modulator. Each klystron feeds its power into two superconducting cavities and its waveguide distribution system is configured without circulators. This DRFS consists of four SC cavities, two klystrons and a modulator was demonstrated in S1-Global project. The results of circulator-less operation in the DRFS will be reported.

WEPC096

Calculation of High Frequency Fields in Resonant Cavities Based on Perturbation Theory*

cavity

2235

K. Brackebusch, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10HRC.
The knowledge of the eigenmodes of resonant accelerator cavities is essential for the determination of their performance characteristics, comprising resonant frequencies and field distributions inside the cavities. Apart from the material properties the eigenmodes of a cavity depend on its geometry. In spite of the high elaborateness during the complex fabrication process, minor deviations of the actual cavity shape from the desired one are inevitable. Moreover, especially superconducting cavities are subject to extreme operating conditions that may cause deformations of their shape. Any geometry perturbation results in a shift of the resonant frequencies and modified field distributions. In this paper, we will analyze a generalization of Slater's theorem proposed in literature. The method should allow for the calculation of resonant frequencies and field distributions of a slightly perturbed cavity by using a set of precomputed eigenmodes of the unperturbed cavity. We will evaluate the practicability of the method by applying it to cavity geometries for which the eigenmodes are analytically known, ascertain the effort of reasonable calculation results and describe its limitations.