EPAC 2006 - Classification:07 Accelerator Technology/T06 Room Temperature RF

07 Accelerator Technology

T06 Room Temperature RF

Paper	Title	Page
TUOCFI03	RF Cavity with Co-based Amorphous Core	983
	M. Kanazawa, T. Misu, A. Sugiura NIRS, Chiba-shi K. Katsuki Toshiba, Yokohama
	A compact acceleration cavity has been developed with new Co-based amorphous cores, which will be used in a dedicated synchrotron for cancer therapy. This core has high permeability that makes the cavity length short, and the cavity with no tuning system is possible with low Q-value of about 0.5. An acceleration cavity consists of two units that have a single acceleration gap at the center, and at the both side of the gap there are quarter wave coaxial resonators. Considering the requirements for easy operation, a transistor power supply was used instead of commonly used tetrode in the final stage RF amplifier. Each resonator has maximum impedance about 400? at 3MHz, and has been attached with 1:9 impedance transformer. In the frequency range from 0.4 to 8 MHz, the acceleration voltage of more than 4kV can be obtained with total input RF power of 8kW. With these performances, the cavity length is short as 1.5m. In this paper the structure of the cavity and their tested high power performances are presented.
	Transparencies
TUPCH110	Upgrade of Main RF Cavity in UVSOR-II Electron Storage Ring	1268
	A. Mochihashi, K. Hayashi, M. Hosaka, M. Katoh, J. Yamazaki UVSOR, Okazaki H. Suzuki Toshiba, Yokohama Y. Takashima Nagoya University, Nagoya
	The UVSOR electron storage ring, which is dedicated to a synchrotron radiation (SR) light source especially for VUV and Soft X-ray, has been improved at the beginning of 2003, and transverse emittance in the improved ring (UVSOR-II)* has been decreased from 165nm-rad to 60 and/or 27nm-rad. Users runs have been performed since September 2003 with 60nm-rad mode, and since then high brilliant SR beams have been supplied routinely for users. The 27nm-rad mode, however, was difficult to introduce to daily operation initially because Touschek lifetime was insufficient in such small emittance condition. To improve the beam lifetime and make full use of the SR beams, we have built new main RF cavity. The aim of the improvement was to increase momentum acceptance by increasing RF accelerating voltage; the previous cavity generated the voltage of 55kV, whereas the new one can generate 150kV in maximum without changing RF frequency (90.1MHz) and transmitter (20kW in maximum). The new cavity has been installed in the UVSOR-II in spring of 2005, and high power commissioning went on smoothly. Because of the improvement, from spring 2005 the UVSOR-II has switched the daily users run to 27nm-rad. *M. Katoh et al., in this conference.
TUPCH111	RF System for the Superconducting Linac Downstream from DEINOS Injector	1271
	P. Balleyguier, J.-L. Lemaire CEA, Bruyères-le-Châtel
	The DEINOS injector will be followed by an accelerator consisting of a LEP-like cryomodule including four 4-cell superconducting cavities. Each of these cavities will be fed by a solid-state amplifier delivering 20 kW in CW operation at 352 MHz. We will use the technology developed by the "Synchrotron SOLEIL" RF team, consisting of merging the power of numerous independent 330 W modules. The design of the low level RF system will be based on our experience with the ELSA accelerator.
TUPCH112	Commissioning of the 100 MeV Preinjector HELIOS for the SOLEIL Synchrotron	1274
	A.S. Setty, D. Jousse, J.-L. Pastre, F. Rodriguez THALES, Colombes R. Chaput, J.-P. Pollina, B. Pottin, M.-A. Tordeux SOLEIL, Gif-sur-Yvette A. Sacharidis EuroMev, Buc
	HELIOS is the 100 MeV electron linac pre-injector of SOLEIL the new French SR facility. It has been supplied by THALES, as a turn-key system on the basis of SOLEIL APD design. The linac was commissioned in October 2005. This paper will remind the main features of the linac, especially on beam-loading compensation, and will give results obtained during the commissioning tests where a special care has been taken for emittance measurements. Specified and measured beam parameters will be compared to show the performance of the entire system.
TUPCH113	Construction of the ALPHA-X Photo-injector Cavity	1277
	J. Rodier, T. Garvey LAL, Orsay D.A. Jaroszynski, V.M. Pavlov, Y.M. Saveliev, M. Wiggins USTRAT/SUPA, Glasgow M.J. de Loos, S.B. van der Geer PP, Soest
	We will describe the construction and low power testing of an RF cavity to be used as a photo-injector for the ALPHA-X project within the Department of Physics at the University of Strathclyde (UK). The gun is a two and a half cell S-band cavity, employing a metallic photo-cathode. RF power is coupled to the gun via a co-axial power coupler. The specification of the gun and the low power measurements made to achieve the correct mode frequency and field flatness will be presented.
TUPCH114	A Ridged Circular Waveguide Ferrite Load for Cavity HOM Damping	1280
	E. Weihreter, V. Duerr, F. Marhauser BESSY GmbH, Berlin
	A normal conducting HOM damped 500 MHz prototype cavity has been tested with three tapered circular double ridged waveguide to coaxial transitions as HOM couplers, featuring maximum longitudinal and transverse HOM impedances below 5 kOhm and 200 kOhm/m respectively. Numerical simulations indicate that these impedance levels can be further reduced by more than a factor of 3 using homogeneous circular double ridged waveguides for improved coupling to the HOMs. In the present paper the layout of an optimised homogeneous waveguide with "in vacuum" ferrite tiles is presented, including mechanical and thermal design considerations. Low power reflectrometry measurements demonstrate good matching of a prototype load, and high power tests of the ferrite absorber elements indicate that the waveguide load is well suited for the cavity HOM power levels present in state of art 3rd generation SR sources.
TUPCH115	Status of the 70 MeV, 70 mA CH Proton-DTL for FAIR	1283
	G. Clemente, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt-am-Main L. Groening GSI, Darmstadt S. Minaev ITEP, Moscow
	The CH-type cavity shows promising features in the low and medium beta range: its high accelerator gradient and the high level of shunt impedance together with the compact transverse dimensions make this new cavity a good candidate for proton acceleration up to 100 MeV. That's why GSI has decided to base the new high current proton injector for the new FAIR facility on that structure: the operating frequency will be 352 MHz with an injection energy of 3 MeV. In order to improve the technical experience on this new kind of structure, IAP has built a model consisting of 8 equidistant gaps for a total cavity-length of 60 cm. Several design options with respect to welding, alignement, cooling and RF joints were studied and compared each other. A new concept for the end-cells geometry will result in the desired flatness of the electric field along the cavity axis and, at the same time, allow effective integration of internal quadruple lenses. Finally, the electric quadruple content of CH-structure gaps is listed in dependence on the geometry of the cell.
TUPCH116	Waveguide Distribution Systems for the European XFEL	1286
	V.V. Katalev, S. Choroba DESY, Hamburg
	In the European X-ray FEL 32 superconducting cavities are connected to a 10 MW multibeam klystron through a waveguide distribution system. The basic waveguide system is a linear system. The XFEL tunnel has limited space for the waveguide system and therefore some new compact high power waveguide components like a motor driven phaseshifter, an iris tuner and an asymmetric shunt tee have been developed. Also alternative layouts of the waveguide distribution system which may have certain advantages have been designed. In this report we will present the different layouts and report on the status of the development of the different new waveguide components.
TUPCH117	Experience with the 208MHz and 52MHz RF Systems for the HERA Proton Accelerator	1289
	R. Wagner, S. Choroba, A. Gamp, T.G. Grevsmuehl, G.M. Moeller DESY, Hamburg A.B. Bienkowski The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
	The RF System for the Hera Proton Ring consists of four 208MHz systems and two 52MHz systems. At injection three of the 208MHz systems are at 70 kV and one System is at 190kV with a phase of 180 degree. The 52 MHz Systems are at 70kV each. During ramping the RF voltage of all cavities follows a ramp table. At flat top at 920GeV both 52 MHz systems are at 50kV and three of the 208MHz Systems are at 190kV while the 180 degree phased system is reduced to 30kV. The typical beam current is 100mA in 180 bunches with a bunch separation of 96 ns. About one year before shutdown of HERA this presentation gives an review of about 14 years operation of the Proton RF System. It is also an overview of the hardware including the beam loading compensation (fast feedback) the tuning system and the other components.
TUPCH118	Manufacturing and Testing of 2.45 GHz and 4.90 GHz Biperiodic Accelerating Structures for MAMI C	1292
	A. Jankowiak, O. Chubarov, H. Euteneuer IKP, Mainz K. Dunkel, C. Piel, H. Vogel, P. vom Stein ACCEL, Bergisch Gladbach
	At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 855MeV to 1500MeV Harmonic Double Sided Microtron, is now on the verge of first operation. For this project ACCEL Instruments GmbH manufactured biperiodic, on axis coupled, standing wave accelerating structures at the frequencies of 2.45GHz and 4.90GHz. Four resp. eleven multicell sections were manufactured, low power characterized and after delivery tested at the high power test stand of IKPH. This paper describes the production and characterization of these structures, presents results of the high power tests, and compares these data with results gained at IKPH for an in house built 4.90GHz prototype and the 2.45GHz structures built in the 1980s. A. Jankowiak et al. "Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI", Proceedings EPAC2002, Paris, p. 1085.
TUPCH120	The Diamond Light Source Booster RF System	1295
	C. Christou, V.C. Kempson Diamond, Oxfordshire K. Dunkel ACCEL, Bergisch Gladbach A. Fabris ELETTRA, Basovizza, Trieste
	The Diamond Light Source (DLS) accelerator complex can be divided into three major components; a 3 GeV 561 m circumference storage ring, a 158.4 m circumference full-energy booster synchrotron and a 100 MeV pre-injector linac. This paper describes the design and presents commissioning results of the RF system for the booster synchrotron. Booster RF commissioning took place in late 2005 and early 2006 and involved the setting-into-operation of a 60 kW IOT amplifier, supplied by Thales Broadcast and Multimedia, a 5-cell copper cavity, manufactured by Accel Instruments, and a low-level RF system designed and built by Sincrotrone Trieste SCpA.
TUPCH121	The IASA Cooling System for the 10 MeV Linac	1298
	A. Karabarbounis, D. Baltadoros, T. Garetsos, C.N. Papanicolas, E. Stiliaris IASA, Athens A. Zolfaghari MIT, Middleton, Massachusetts
	A de-ionized water cooling system for the IASA room temperature 10 MeV CW Linac has been constructed and successfully installed. Commissioning is undergoing achieving resistivity larger to 5M?cm with a temperature accuracy of for all three linacs. Three ways mixing valves with a stepping capability of one thousand different mixing steps fulfill independently for each section the required temperature stability and the appropriate resonance frequency to our cavities. The RF requirements for the three linacs is 190kW provided by a single high power klystron tube capable to deliver up to 500 kW CW at 2380 MHz. The klystron is been cooled with a parallel similar cooling system and a third system cools our Aluminum waveguide complex. In this paper we will present the design, specifications and results of our preliminary tests. A sophisticated control and interlock system based on EPICS guarantees the proper functioning of the system.
TUPCH123	Dipole Stabilizing Rods System for a Four-vane RFQ: Modeling and Measurement on the TRASCO RFQ Aluminum Model at LNL	1301
	F. Grespan, A. Palmieri, A. Pisent INFN/LNL, Legnaro, Padova
	The Dipole Stabilizing Rods (DSR's) are devices used in order to reduce a priori the effect of perturbation on the operating mode of a four-vane RFQ caused by neighboring dipole modes by increasing the frequency spacing between the TE210 mode and dipole modes, without, in principle, affecting the quadrupole TE210 mode. They have proven to be particularly useful in the case of coupled RFQ's whose overall length is significantly greater than the operating wavelength. In this article we present a circuit model of such DSR's, that, used in combination with a transmission line model of a four vane RFQ, has allowed us to predict the dimensioning of the DSR's in the case of the aluminum model of TRASCO RFQ. The DSR parameters and, in general, the accuracy of the model have been also confirmed by HFSS simulations and by RF measurements on the above-mentioned model.
TUPCH124	Improvement of Co-based Amorphous Core for Untuned Broadband RF Cavity	1304
	A. Sugiura, M. Kanazawa, T. Misu, S. Yamada NIRS, Chiba-shi K. Katsuki, T. Kusaka, K. Sato Toshiba, Yokohama
	We have developed a cobalt-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the Co-based amorphous core's physical properties and performance. Improvement of the new core coated by new materials surface of ribbon is also described.
TUPCH126	Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities	1307
	T. Abe, T. Kageyama, Y. Saito, H. Sakai, Y. Sato, Y. Takeuchi KEK, Ibaraki Z. Kabeya, T. Kawasumi MHI, Nagoya T. Nakamura, S. Nishihashi, K. Tsujimoto Asahi Kinzoku Co., Ltd., Gifu K. Tajiri Churyo Engineering Co., Ltd., Nagoya
	We plan to apply a new copper electroplating with a high purity and a high electric conductivity to normal-conducting RF cavities for electron or positron storage rings with a high current beam. As reported in 2005 Particle Accelerator Conference, our first test cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with its fabrication process.
TUPCH127	Fine Grooving of Conductor Surfaces of RF Input Coupler to Suppress Multipactoring	1310
	T. Abe, T. Kageyama, H. Sakai, Y. Takeuchi KEK, Ibaraki
	An RF input coupler to feed high power into an accelerating cavity with heavy beam loading undergoes many multipactoring zones due to the wide range of the input RF power. Furthermore, a regular coaxial line is more subject to multipactoring than a rectangular waveguide because of the uniformity of the electromagnetic field. Grooving the conductor surfaces of the coaxial line is a promising method to suppress multipactoring under any conditions expected in the above cases. This paper reports results of our multipactoring simulation study and the high power test of the input coupler with a grooved coaxial line.
TUPCH128	New Cutting Scheme of Magnetic Alloy Cores for J-PARC Synchrotrons	1313
	C. Ohmori, S. Anami, E. Ezura, Y. Funahashi, K. Hara, K. Hasegawa, A. Takagi, M. Toda, K. Ueno, M. Yoshii KEK, Ibaraki Y. Morita, T. Yoshioka ICEPP, Tokyo M. Nomura, A. Schnase, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	A new cutting method using a grindstone was developed to manufacture the magnetic alloy cores. The problem of local temperature rise around the cut surfaces was solved. Long-term high-power tests have been performed for both J-PARC RCS and MR RF systems. Mechanism of local heating, new cutting scheme, and manufacturing method are presented.
TUPCH129	Conceptual Design of a 3rd Harmonic Cavity System for the LNLS Electron Storage Ring	1316
	N.P. Abreu, O.R. Bagnato, R.H.A. Farias, M.J. Ferreira, C. Pardine, P.F. Tavares LNLS, Campinas
	The installation of a second RF cavity in the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS) at the end of 2003 brought about longitudinal instabilities driven by one of the HOMs of the new cavity. Even though the operational difficulties related to these unstable modes were successfully overcome by means of a combination of cavity tuning (using temperature and plunger adjustments) with phase modulation of the RF fields at the second harmonic of the synchrotron frequency, a more appropriate technique to avoid those problems is the use of higher harmonic cavities, which have the important advantage of providing damping of the longitudinal modes without increasing the energy spread, i.e., without compromising the longitudinal emittance. In this work we present the design of a passive higher harmonic cavity system optimized for operation at the LNLS storage ring. The parameters for a set of cavities as well as the analysis of some of the effects that they may introduce in the beam dynamics are presented. An overview of the technical aspects related to the project, construction and installation of the cavities in the storage ring is also presented.
TUPCH130	Development of the Feed-forward System for Beam Loading Compensation in the J-PARC RCS	1319
	F. Tamura, M. Nomura, A. Schnase, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Yoshii KEK, Ibaraki
	In the J-PARC Rapid Cycling Synchrotron (RCS), the heavy beam loading effects due to the high intensity proton beam must be compensated for stable acceleration. The beam feedforward technique is used to compensate the beam loading in the RCS. We present the development of the feedforward system. We designed and built the full-digital system with modern FPGAs to realize high accuracy, stability and predictability of the compensation. Because of the low Q value of each accelerating cavity, the wake voltage consists of not only the accelerating harmonic component but also higher harmonics. Thus, the system is designed to compensate the beam loading at several harmonics. The system has two parts. In the first part, vector components of the selected harmonic are detected from the beam signal picked up by a wall current monitor. The compensation RF signal is generated from the vector components with proper gain and phase in the latter part. The gain and phase are set individually for each harmonic and each cavity of the twelve cavities. We also present the preliminary test results of the newly developed modules.
TUPCH131	High Power Test of MA Cavity for J-PARC RCS	1322
	M. Yamamoto, M. Nomura, A. Schnase, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken S. Anami, E. Ezura, K. Hara, C. Ohmori, A. Takagi, M. Toda, M. Yoshii KEK, Ibaraki K. Hasegawa JAEA, Ibaraki-ken
	We have been constructing the RF system for the J-PARC RCS. Almost all of the power supplies and the tube amplifiers have been constructed, and the cavities are under construction. All of them are tested at the experimental hall before installing into the J-PARC RCS building. We test the hybrid cavity scheme to realize the optimum cavity Q-value. The results of the test are described.
TUPCH132	Higher Order Mode (HOM) Damper of 500 MHz Damped Cavity for ASP Storage Ring	1325
	J. Watanabe, K. Nakayama, K. Sato, H. Suzuki Toshiba, Yokohama M. Izawa KEK, Ibaraki A. Jackson, G. LeBlanc, K. Zingre ASP, Clayton, Victoria T. Koseki RIKEN/RARF/CC, Saitama N. Nakamura, H. Sakai, H. Takaki ISSP/SRL, Chiba
	TOSHIBA has delivered the storage ring RF system for the Australian Synchrotron Project(ASP). Two pairs of the 500MHz Higher Order Mode(HOM) damped cavities were applied for this system. Two on-centered and one off-centered dampers were attached for damping the longitudinal HOM impedance down to less than 20kOhm/GHz. In order to reduce the coupling of off-center damper for accelerating mode and improve cooling power of damper, New HOM damper was designed by optimizing SiC absorber structure and damper antenna length using HFSS code. The design and manufacture of the new HOM damper and the test are described.
TUPCH133	Comparison of Measured and Calculated Coupling between a Waveguide and an RF Cavity Using CST Microwave Studio	1328
	J. Shi, H. Chen, S. Zheng TUB, Beijing D. Li LBNL, Berkeley, California R.A. Rimmer, H. Wang Jefferson Lab, Newport News, Virginia
	Accurate predications of RF coupling between an RF cavity and ports attached to it have been an important study subject for years for RF coupler and higher order modes (HOM) damping design. We report recent progress and a method on the RF coupling simulations between waveguide ports and RF cavities using CST Microwave Studio in time domain (Transit Solver). Comparisons of the measured and calculated couplings are presented. The simulated couplings and frequencies agree within ~ 10% and ~ 0.1% with the measurements, respectively. We have simulated couplings with external Qs ranging from ~ 100 to ~ 100, 000, and confirmed with measurements. The method should also work well for higher Qs, and can be easily applied in RF power coupler designs and HOM damping for normal-conducting and superconducting cavities.
TUPCH134	RF Characteristics of the PEFP DTL	1331
	H. S. Kim, Y.-S. Cho, H.-J. Kwon, K.T. Seol KAERI, Daejon
	A conventional 20 MeV Drift Tube Linac (DTL) for the Proton Engineering Frontier Project (PEFP) has been developed as a low energy section of a 100 MeV accelerator. The 20 MeV DTL consists of 4 tanks with 152 cells. The machine has a unique feature of driving the 4 tanks with a single klystron. Therefore it has several control knobs to compensate the errors of each tank during operation. To develop the RF control scheme, the variations of the RF parameters of each tank were measured under various environmental conditions such as wall temperature, cooling water temperature, and cooling water pressure. In addition, the behaviors of the RF parameters among the tanks were also monitored during high power operation. In this paper, the measurement results are discussed and the control scheme based on the results are proposed.
TUPCH135	Characteristics of the PEFP 3 MeV RFQ	1334
	H.-J. Kwon, Y.-S. Cho, J.-H. Jang, H. S. Kim, K.T. Seol KAERI, Daejon
	A four-vane type 3 MeV, 350 MHz RFQ (Radiofrequency Quadrupole) has been developed as a front end part of PEFP (Proton Engineering Frontier Project) 100 MeV accelerator. After the completion of field tuning and high power conditioning at reduced duty, the initial operation of the RFQ with beam was carried out. During the initial test period, several parameters related with the RF and beam were measured to characterize the performance of the RFQ. Based on these measurements, several suggestions for further system improvement were proposed. In this paper, the initial test results are discussed and the suggestions for the system improvement are summarized.
TUPCH136	Phase Measurement and Compensation System in PLS 2.5 GeV Linac for PAL-XFEL	1337
	W.H. Hwang, J. Choi, Y.J. Han, J.Y. Huang, H.-G. Kim, S.-C. Kim, I.S. Ko, W.W. Lee PAL, Pohang, Kyungbuk
	In PAL, We are preparing the 3.7 GeV PALXFEL project by upgrading the present 2.5GeV Linac. In present PLS Linac, the specifications of the beam energy spread and rf phase are 0.6%(peak) and 3.5 degrees(peak) respectively. And the output power of klystron is 80 MW at the pulse width of 4 ? and the repetition rate of 10 Hz. In XFEL, the specifications of the beam energy spread and rf phase are 0.03%(rms) and 0.01 degrees(rms) respectively. We developed an analogue and a digital phase measurement and rf phase compensation system for stable beam quality. This paper describes the microwave system for the PALXFEL and the rf phase measurement and phase compensation system.
TUPCH137	Design of the RF System for 30 MeV Cyclotron	1340
	I.S. Jung, D.H. An, J.-S. Chai, H.B. Hong, S.S. Hong, M.G. Hur, H.S. Jang, J. Kang, J.H. Kim, Y.-S. Kim, M.Y. Lee, T.K. Yang KIRAMS, Seoul K.H. Kwon SKKU, Seoul
	LAD (Lab. of Accelerator Development) in KIRAMS (Korea Institute of Radiological & Medical Sciences) developed 13MeV medical cyclotron, named by KIRAMS-13, for PET (Positron Emission Tomography) in 2001. Now, KIRAMS-13 is widespread in Korea through the national project, "Development of Cyclotron and FDG Synthesis module." But, there is just one cyclotron for SPECT(Single Photon Emission Computed Tomography) in Korea, which is made by IBA, Belgium. If some problems are happened, we should shut off the cyclotron until IBA engineer fixes them. So, we decide to develop a 30MeV cyclotron, named KIRAMS-30, which has high-performance compared with existing commercial cyclotrons and will install this machine to radioactive isotopes production and researches in Advanced Radiation Technology Institute. In this paper, we design RF system, such as cavity, power coupler, and so on. At design of RF components, we consider mechanical stability, RF heating and cooling, arcing and multipacting, low maintenance. We simulate KIRAMS-30 with MWS (MicroWave Studio) and present simulation results.
TUPCH140	Studies of Thermal Fatigue Caused by Pulsed RF Heating	1343
	S.V. Kuzikov, Yu. Danilov, N.S. Ginzburg, N.Yu. Peskov, M.I. Petelin, A. Sergeev, A.A. Vikharev, N.I. Zaitsev IAP/RAS, Nizhny Novgorod A.V. Elzhov, A. Kaminsky, O.S. Kozlov, E.A. Perelstein, S. Sedykh, A.P. Sergeev JINR, Dubna, Moscow Region I. Syratchev CERN, Geneva
	A future linear collider with a multi-TeV level of energies of the collided particles in the center of masses is naturally associated with high frequencies and a high power RF level. One of the interfering factors in this way is an effect of copper damage due to multi-pulse mechanical stress caused by high-power microwaves. In order to get new information about this effect, we started an experiment with the test cavity fed by 30 GHz FEM oscillator (15-30 MW, 100-200 ns, 0.5 - 1 Hz). Now we finished the second phase of this experiment where the test cavity was irradiated by 0.1 millions of RF pulses with temperature rise ~140 C in each pulse. The third phase is the experiment with 1 million pulses. In the next planned experiment with 36 GHz magnetron (0.1-0.15 MW, 1-2 mks, 0.01 - 1 kHz) we are going to investigate the thermal fatigue in most interesting for collider application region of temperatures (30-50 C). It is expected that these two experiments will supply necessary statistical information for the developed theory of the thermal fatigue in order to extrapolate lifetime numbers to other values of the temperature rise and pulse duration.
TUPCH141	New Developments for the RF System of the ALBA Storage Ring	1346
	F. Pérez, B. B. Baricevic, D. Einfeld, H. Hassanzadegan, A. Salom, P. Sanchez ALBA, Bellaterra
	ALBA is a 3 GeV, 400 mA, 3rd generation Synchrotron Light Source that is in the construction phase in Cerdanyola, Spain. The RF System will have to provide 3.6 MV of accelerating voltage and restore up to 540 kW of power to the electron beam. For that six RF plants, working at 500 MHz, are foreseen. The RF plants will include several new developments: 1) DAMPY cavity: the normal conducting HOM damped cavity developed by BESSY and based in the EU design; six will be installed. 2) CaCo: A cavity combiner to add the power to two 80 kW IOTs to produce the 160 kW needed for each cavity. 3) WATRAX: A waveguide transition to coaxial, specially designed to feed the DAMPY cavities due to the geometrical and cooling constrains. 4) IQ LLRF: The low level RF will be based on the IQ modulation/demodulation technique, both analogue and digital approach are being pursued. This paper describes the Storage Ring RF System and reports about the status of these new developments.
TUPCH142	Development of a Novel RF Waveguide Vacuum Valve	1349
	A. Grudiev CERN, Geneva
	The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the T·10⁰¹ mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the T·10⁰¹ mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·10⁰¹ mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) are presented showing in particular that the rf power transmission losses are below 1%.
TUPCH143	High Gradient Tests of an 88 MHZ RF Cavity for Muon Cooling	1352
	C. Rossi, R. Garoby, F. Gerigk, J. Marques Balula, M. Vretenar CERN, Geneva
	The scheme for a Muon Cooling channel developed at CERN in the frame of Neutrino Factory studies foresees the use of 44 and 88 MHz cavities operating at a real-estate gradient as high as 4 MV/m. To assess the feasibility of this scheme, including high-gradient operation at relatively low frequency and the production and handling of high RF peak powers, a test stand was assembled at CERN. It included an 88 MHz resonator reconstructed from a 114 MHz cavity previously used for lepton acceleration in the PS, a 2.5 MW final amplifier made out of an old linac unit improved and down-scaled in frequency, and a PS spare amplifier used as driver stage. After only 160 hours of conditioning the cavity passed the 4 MV/m level, with local peak surface field in the gap exceeding 25 MV/m (2.4 times the Kilpatrick limit). The gradient was limited by the amplifier power, the maximum RF peak output power achieved during the tests being 2.65 MW. This paper presents the results of the tests, including an analysis of field emission from the test cavity, and compares the results with the experience in conditioning ion linac RF cavities at CERN.
TUPCH144	Automatic Conditioning of the CTF3 RF System	1355
	J.P.H. Sladen, S. Deghaye, S. Livesley, J. Marques Balula, J. Mourier, J.-M. Nonglaton CERN, Geneva A. Dubrovsky JINR, Dubna, Moscow Region
	The RF system of CTF3 (CLIC Test Facility 3) includes ten 35 MW to 40 MW 3 GHz klystrons and one 20 MW 1.5 GHz klystron. High power RF conditioning of the waveguide network and cavities connected to each klystron can be extremely time consuming. Because of this, a fully automatic conditioning system has been developed within a CERN JINR (Dubna) collaboration. It involves relatively minor hardware additions, most of the work being in application and front-end software. The system has already been used very successfully.
TUPCH145	The MUCOOL RF Program	1358
	J. Norem ANL, Argonne, Illinois A. Bross, A. Moretti, B. Norris, Z. Qian Fermilab, Batavia, Illinois D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California R.A. Rimmer Jefferson Lab, Newport News, Virginia R. Sandstrom DPNC, Genève Y. Torun IIT, Chicago, Illinois
	Efficient muon cooling requires high RF gradients in the presence of high (~3T) solenoidal fields. The Muon Ionization Cooling Experiment (MICE) also requires that the x-ray production from these cavities is low, in order to minimize backgrounds in the particle detectors that must be located near the cavities. These cavities require thin Be windows to ensure the highest fields on the beam axis. In order to develop these cavities, the MUCOOL RF Program was started about 6 years ago. Initial measurements were made on a six-cell cavity and a single-cell pillbox, both operating at 805 MHz. We have now begun measurements of a 201 MHz pillbox cavity. This program has led to new techniques to look at dark currents, a new model for breakdown and a general model of cavity performance based on surface damage. The experimental program includes studies of thin Be windows, conditioning, dark current production from different materials, magnetic-field effects and breakdown. We will present results from measurements at both 805 and 201 MHz.
TUPCH146	The Interactions of Surface Damage on RF Cavity Operation	1361
	J. Norem, A. Hassanein, Z. Insepov ANL, Argonne, Illinois A. Bross, A. Moretti, Z. Qian Fermilab, Batavia, Illinois D. Li, M.S. Zisman LBNL, Berkeley, California R.A. Rimmer Jefferson Lab, Newport News, Virginia D.N. Seidman, K. Yoon NU, Evanston, Illinois Y. Torun IIT, Chicago, Illinois
	Studies of low frequency RF systems for muon cooling has led to a variety of new techniques for looking at dark currents, a new model of breakdown, and, ultimately, a model of RF cavity operation based on surface damage. We find that cavity behavior is strongly influenced by the spectrum of enhancement factors on field emission sites. Three different spectra are involved: one defining the initial state of the cavity, the second determined by the breakdown events, and the third defining the equilibrium produced as a cavity operates at its maximum field. We have been able to measure these functions and use them to derive a wide variety of cavity parameters: conditioning behavior, material, pulse length, temperature, vacuum, magnetic field, pressure, gas dependence. In addition we can calculate the dependence of breakdown rate on surface field and pulse length. This work correlates with data from Atom Probe Tomography. We will describe this model and new experimental data.
TUPCH147	High Pressure RF Cavities in Magnetic Fields	1364
	P.M. Hanlet, M. Alsharo'a, R. E. Hartline, R.P. Johnson, M. Kuchnir, K. Paul Muons, Inc, Batavia C.M. Ankenbrandt, A. Moretti, M. Popovic Fermilab, Batavia, Illinois D.M. Kaplan, K. Yonehara Illinois Institute of Technology, Chicago, Illinois
	A study of RF breakdown in pressurized cavities immersed in strong magnetic fields has begun as part of a program to develop RF cavities filled with dense hydrogen gas to be used for muon ionization cooling. A pressurized 805 MHz test cell is being used at Fermilab to compare the conditioning and breakdown behavior of copper, molybdenum, and beryllium electrodes as functions of hydrogen and helium gas densities and magnetic field strength. These results will be compared to the predicted or known RF breakdown behavior of these metals in vacuum with and without external magnetic fields.
TUPCH148	201 MHz Cavity R&D for MUCOOL and MICE	1367
	D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California A. Bross, A. Moretti, B. Norris Fermilab, Batavia, Illinois J. Norem ANL, Argonne, Illinois H.L. Phillips, R.A. Rimmer, M. Stirbet Jefferson Lab, Newport News, Virginia M. Reep, D.J. Summers UMiss, University, Mississippi Y. Torun IIT, Chicago, Illinois
	We describe the design, fabrication and preliminary testing of the prototype 201 MHz copper cavity for a muon ionization cooling channel. Application of the cavity includes the Muon Ionization Cooling Experiment (MICE) as well as cooling channels for a neutrino factory or a muon collider. This cavity was developed by the US MUCOOL collaboration and is being tested in the MUCOOL Test Area (MTA) at Fermilab. In order to achieve a high accelerating gradient, the cavity beam irises are terminated by a pair of curved, thin beryllium windows. Several of the fabrication methods developed for this cavity and the windows are novel and offer significant cost savings compared to conventional construction methods. Cavity thermal and RF performance will be compared to FEA modeling predictions. RF commissioning results will be presented.
TUPCH149	Design of a 10 MHz Heavy Ion RFQ for a RIA Post Accelerator	1370
	S.O. Schriber, V. Andreev NSCL, East Lansing, Michigan
	Design of a 10 MHz heavy ion RFQ for the RIA post accelerator is described. Main rf and mechanical parameters of the proposed accelerator are given. This 10 MHz RFQ is capable of accelerating beams from an initial energy of 2 keV/u to 8 keV/u covering a charge to mass ratio from 1/10 to 1/240.