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klystron

      
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MOP25 The LEBRA 125 MeV Electron Linac for FEL And PXR Generation electron, linac, laser, undulator 90
 
  • K. Hayakawa, Y. Hayakawa, K. Ishiwata, K. Kanno, K. Nakao, T. Sakai, I. Sato, T. Tanaka
    LEBRA, Funabashi
  • K. Yokoyama
    KEK, Ibaraki
  A 125 MeV electron linac has been constructed at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University for Free Electron Laser (FEL) and Parametric X-ray (PXR) generation. Two klystrons feed rf power of approximately 20 MW peak and 20 μsec pulse duration each to an injector and three 4 m accelerating structures. Phase of the rf fed to each component is controlled independently. Two accelerating structures connected with the second klystron and a ninety degrees bending system as a momentum analyzer constitute a magnetic bunching system. Electron bunches of 3 to 4 psec width formed at the injector are compressed to within 1 psec during passing through the magnetic bunching system. Peak current of the electron beam injected to the FEL system installed downstream of the momentum analyzer is expected to be about 50 A. FEL lasing has been achieved at the wavelength range from 1 to 6 mm. Estimated peak power of the extracted FEL light pulse is about 2 MW. Applied researches using the FEL started last autumn. Preliminary experiment for the PXR generation has been continued.  
 
MOP31 Development of a C-band Accelerating Module for SUPERKEKB linac, positron, acceleration, electron 108
 
  • S. Ohsawa, M. Ikeda, K. Kakihara, T. Kamitani, T. Oogoe, T. Sugimura, S. Yamaguchi, K. Yokoyama
    KEK, Ibaraki
  High power rf processing of 1 m C-band accelerating section for Super KEKB was successfully performed and power corresponding to 42 MV/m was achieved. Processing data were accumulated including acoustic sensor to find the arcing position. No structural damage was observed from the phase shift measurement performed after the processing. Processed accelerator was installed in the beam line of KEKB linac and being re-processed. The beam acceleration of 40 MV/m was successfully achieved in October 2003. Present status of C-band accelerator development is reported.  
 
MOP49 Status And Operating Experience of The TTF Coupler vacuum, linac, superconductivity, free-electron-laser 156
 
  • W.-D. Möller, D. Kostin
    DESY, Hamburg
  Five accelerating modules are installed in the VUV FEL linac so far. This includes 40 high power couplers connected to the superconducting cavities, eight in every module. All of them are processed and operated up to the cavity performance limits. The coupler processing procedure is described. The performance in relation to the test results on the coupler test stands are discussed.  
Transparencies
 
TU201 The KEK C-Band RF System for a Linear Collider linac, collider, linear-collider, RF-structure 256
 
  • H. Matsumoto, S. Takeda, S.S. Win, M. Yoshida
    KEK, Ibaraki
  • H. Baba, T. Shintake
    RIKEN Spring-8 Harima, Hyogo
  • J-O. Oh
    PAL, Pohang
  The C-band (5712 MHz) main linac has been developed just motivated by the urgent and essential physics program at the e+e- linear collider. In total ~8000 accelerating structures and ~4000 klystrons with modulators are needed for 500 GeV C.M. energy. Therefore these units have to meet strict requirements for: high reliability, simplicity, easy operation, reasonable power efficiency and low cost. This list provides a guiding principle and the boundary conditions for our design work. We have already developed the conventional and PPM type 50 MW class C-band klystrons, modulators, and HOM-free accelerator structures. The first high power an rf compressor cavity made of a low thermal expansion material was designed to provide stable operation even with a very high Q of 200 k, it was successfully operated an output rf power of 135 MW at KEK. The C-band linac rf-system will be used for the SASE-FEL project at SPring-8, but it will also serve to verify the design and components, which can eventually be deployed for the main linac rf system in a future linear collider.  
Transparencies
 
TUP44 Linac Upgrades for FERMI@ELETTRA linac, gun, injection, laser 366
 
  • G. D'Auria, R.J. Bakker, P. Craievich, G. De Ninno, S.D. Di Mitri, M. Ferianis, P.G. Pangon, R.L. Rumiz, T.L. Tosi, D. Zangrando
    Sincrotrone Trieste S.C.p.A., Basovizza, Trieste
  • C. Bocchetta, M. Danailov, B. Diviacco, V. Verzilov
    ELETTRA, Basovizza, Trieste
  To fulfill the stringent requirements expected from the FERMI project, the existing Linac needs some modifications in the layout and an upgrading of the present plants. Moreover, for the next two years, until the new injection system (now under construction) is fully commissioned, the Linac has to be kept in operation as injector for the ELETTRA Storage Ring. Therefore most of the planned activities have to be carried out without interfering with the normal operation of the machine. Details on the new Linac layout and related activities are discussed.  
 
TUP64 Bunch Length Measurements at LEBRA electron, linac, simulation, undulator 411
 
  • K. Yokoyama
    KEK, Ibaraki
  • K. Hayakawa, Y. Hayakawa, K. Nakao, I. Sato, T. Tanaka
    LEBRA, Funabashi
  The bunch length of the electron beam from the FEL linac at LEBRA (Laboratory for Electron Beam Research and Application) was estimated from the phase ellipse coefficient which is deduced from the dependence of the beam spread on the accelerating phase. The bunch length of FWHM was estimated approximately 0.33 mm from the results of the experiments. Besides, the pulse length of the FEL lights around the wavelength of 1.5 μm was measured by means of the autocorrelation. The pulse length was less than 0.06 mm according to the number of interfacial waves. These results indicate that the pulse length of the FEL lights isn’t equivalent to the electron bunch length.  
 
TUP65 RF Tuning Schemes for J-PARC DTL and SDTL linac, simulation, injection, diagnostics 414
 
  • M. Ikegami
    KEK, Ibaraki
  • Y. Kondo, A. Ueno
    JAERI, Ibaraki-ken
  J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. In high-current proton linacs, precise tuning of RF amplitude and phase is indispensable to reduce uncontrolled beam loss and beam-quality deterioration. Especially, accurate RF tuning is essential for J-PARC linac, because requirement for the momentum spread is extremely severe to enable effective injection to the succeeding RCS (Rapid Cycling Synchrotron). In this paper, planned tuning schemes for the DTL and SDTL are presented together with the beam diagnostic layout for the tuning.  
 
TUP80 A Long-Pulse Modulator for the TESLA Test Facility (TTF) cathode, linac, coupling, linear-collider 459
 
  • W. Kaesler
    PPT, Dortmund
  The long-pulse (1.6 ms) klystron modulator for TTF is a hardtube pulser using a Bouncer-circuit for droop compensation. It is built up with new advanced components representing industrial standards. The on-/off switch is a rugged 12 kV IGCT-stack with a fast 4kA turn-off capability. The 100 kJ storage capacitor bank contains only three capacitors with self-healing, segmented PP-foil technology. A new 100 kA solid-state switch based on light triggered thyristors (LTT) replaced the standard ignitrons as crowbar switches. The 300 kW high voltage power supply is based on modern switched mode technology.  
 
TUP91 Compact Electron-Linac Design Concept for a Gamma Ray Source linac, electron, linear-collider, collider 492
 
  • K. C. D. Chan, B.E. Carlsten, G. Dale, R. Garnett, C. Kirbie, F.L. Krawczyk, S.J. Russell, T.P. Wangler
    LANL, Los Alamos, New Mexico
  • E. Wright
    CPI, Palo Alto, California
  Gamma-ray sources, particularly sources that are easily transportable, are in high demand for different homeland security applications. We have carried out a review of commercially available electron-linac-based sources, and have investigated alternative compact electron-linac systems that use updated technologies compared with sources that are available commercially. As the results, we propose to develop a new source using an electron linac operating at 17 GHz. It uses a klystron, instead of a magnetron, and a IGBT-switched HV power supply. The source design takes advantages of the advances in X-band linac technology and solid-state HV technology. The higher frequency and upgraded technologies offer smaller size, lighter weight, better efficiency, easier operation, and higher reliability, compared with commercially-available linacs. In this paper, we will describe the source design and our choice of technologies.  
 
TUP98 The Finite State Machine for Klystron Operation for VUV-FEL and European X-FEL Linear Accelerator cathode, power-supply, vacuum, bunching 510
 
  • W. Cichalewski, B. Koseda, A. Napieralski
    TUL, Lodz
  • F.-R. Kaiser, S. Simrock
    DESY, Hamburg
  In order to provide a pulsed RF power signal that fulfills all designers and users demands the work on power supplies, pulse transformers, waveguides and klystrons has to be well coordinated. Because operators not engineers will operate mention user facility therefore software has to be implemented in order to automate the enormous quantity of hardware operation accompanying regular operation of linear accelerator collider. A finite state machine is adequate formal description of reactive systems that has become starting point for designing our control software. To present the complexity of the task that establishing FSM for Klystron system would be, one has to become acquainted with complexity of the system itself. Therefore this article describes the construction and principles of the klystron and modulator as well as ideas concerning the implementation of a FSM for such a system.  
 
WE205 KEKB Injector Linac and Upgrade for SuperKEKB linac, acceleration, injection, positron 549
 
  • S. Michizono
    KEK, Ibaraki
  KEKB Injector linac has provided the 8 GeV electrons and 3.5 GeV positrons to the KEKB asymmetric collider rings designed for the B-physics study. The KEKB has recorded the highest luminosity records to which the linac contributes with an advanced operational stability. The dualbunch injection and continuous injection schemes have been adopted. The operational status of the KEKB injector linac is summarized here. The Super KEKB project aiming for the ten-times higher luminosity is under consideration as the upgrade of KEKB. In this upgrade, the injector linac has to increase the positron acceleration energy from 3.5 GeV to 8 GeV. In order to double the acceleration field (from 20 to 40 MV/m), the C-band rf system has been tested. The newly developed components, such as an acceleration structure and an rf window, are summarized. A C-band acceleration structure is installed in KEKB linac after the rf conditioning of more than 40 MW. The energy gain of more than 40 MV/m is confirmed by the beam analysis. The C-band acceleration unit has been operated continuously for the stability test. The recent operational status of the c-band acceleration unit will be also reported.  
Transparencies
 
TH201 IOT RF Power Sources for Pulsed and CW Linacs linac, gun, electron, simulation 574
 
  • H.P. Bohlen
    CPI, Palo Alto, California
  • Y. Li, R.N. Tornoe
    CPI/EIMAC, San Carlos, California
  For many years, klystrons have been the preferred RF power amplifiers for both pulsed and CW linacs at UHF and higher frequencies. Their properties have earned them that position. But in recent years in UHF terrestrial television transmitters the earlier predominant klystron has been replaced the Inductive Output Tube (IOT) because the IOT provides higher efficiency and, due to its excellent linearity, can handle the simultaneous amplification of both the vision and the sound signal. Its robustness and life expectancy equals that of a klystron, and it more than compensates its lower gain by a lower price and a smaller size. For linac operation, derivates of UHF TV IOTs, capable of up to 80 kW CW output power, are already available and operating. In L-Band, they are presently joined by recently developed 15 to 30 kW CW IOTs. HOM-IOTs are expected to extend the CW range in UHF to 1 MW and beyond. Pulsed operation of an IOT can be achieved without a high-voltage modulator. Since the beam current is grid-controlled it is sufficient to pulse the drive power.  
Transparencies
 
THP29 Development of C-band Accelerating Section for SuperKEKB acceleration, linac, positron, coupling 663
 
  • T. Kamitani, N. Delerue, M. Ikeda, K. Kakihara, S. Ohsawa, T. Oogoe, T. Sugimura, T. Takatomi, S. Yamaguchi, K. Yokoyama
    KEK, Ibaraki
  • Y. Hozumi
    GUAS/AS, Ibaraki
  For the luminosity upgrade of the present KEK B-factory to SuperKEKB, the injector linac has to increase the positron acceleration energy from 3.5 to 8.0 GeV. In order to double the acceleration field gradient from 21 to 42 MV/m, design studies on C-band accelerator module has started in 2002. First prototype 1-m long accelerating section has been fabricated based upon a design which is half scale of the present S-band section. High power test of the C-band section has been performed at a test stand and later at an accelerator module in the KEKB injector linac. In a beam acceleration test, a field gradient of 41 MV/m is achieved with 43 MW RF power from a klystron. This paper report on the recent status of the high-power test and also the development of a second prototype section.  
 
THP32 New Accelerating Modules RF Test at TTF linac, pick-up, superconductivity, radiation 672
 
  • D. Kostin
    DESY, Hamburg
  Five new accelerating modules were installed into the TTF tunnel as a part of the VUV FEL Linac. They are tested prior to the linac operation. The RF test includes processing of the superconducting cavities, as well as maximum module performance tests. The test procedure and the achieved performance together with the test statistical analysis are presented.  
 
THP34 A High-Power Test of an X-Band Molybdenum-Iris Structure vacuum, linear-collider, collider, linac 678
 
  • W. Wuensch, A. Grudiev, T. Heikkinen, I. Syratchev, T. Taborelli, I. Wilson
    CERN, Geneva
  • C. Adolphsen
    SLAC/NLC, Menlo Park, California
  • S. Döbert
    SLAC, Stanford
  In order to achieve accelerating gradients above 150 MV/m, alternative materials to copper are being investigated by the CLIC study. The potential of refractory metals has already been demonstrated in tests in which a tungsten-iris and a molybdenum-iris structure reached 150 and 193 MV/m respectively (30 GHz and a pulse length of 15 ns). In order to extend the investigation to the pulse lengths required for a linear collider, a molybdenum-iris structure scaled to X-band was tested at the NLCTA. The structure conditioned to only 65 MV/m (100 ns pulse length) in the available testing time and much more slowly than is typical of a copper structure. However the structure showed no sign of saturation and a microscopic inspection of the rf surfaces corroborated that the structure was still at an early stage of conditioning. The X-band and 30 GHz results are compared and what has been learned about material quality, surface preparation and conditioning strategy is discussed.  
Transparencies
 
THP39 Operation of a 1.3 GHz, 10 MW Multiple Beam Klystron cathode, electron 693
 
  • H.P. Bohlen, A. Balkcum, M. Cattelino, L. Cox, M. Cusick, S. Forrest, F. Friedlander, A. Staprans, E. Wright, L. Zitelli
    CPI, Palo Alto, California
  • K. Eppley
    SAIC, Boston
  Results will be reported for a 1.3 GHz, 10 MW multiple beam klystron that is being developed for the TESLA linear accelerator facility. The design parameters for the device are 10 MW peak RF output power with 150 kW average power, 1.5 ms pulse length, 65% efficiency, 50 dB gain, and 2.0 A/cm2 maximum cathode loading. Initial testing of the device has validated the basic design approach. Six 120 kV electron beams of measurably identical currents of 22.9 A each have been successfully propagated through the klystron circuit with 99.5% DC beam transmission at full operating video duty and with 98.5% saturated RF transmission. A peak power of 10 MW at 1.3 GHz with 60% efficiency and 49 dB of gain has been measured.  
 
THP42 NLC Hybrid Solid State Induction Modulator induction, pulsed-power, controls, vacuum 697
 
  • R.L. Cassel, M. Nguyen, G.C. Pappas, J.E. deLamare
    SLAC, Stanford
  • C. Brooksby, E. Cook, J. Sullivan
    LLNL, Livermore
  The Next Linear Collider accelerator proposal at SLAC requires a high efficiency, highly reliable, and low cost pulsed power modulator to drive the X-band klystrons. The original NLC envisions a solid state induction modulator design to drive up to 8 klystrons to 500 kV for 3 μs at 120 PPS with one modulator delivering greater than 1,000 MW pulse, at 500 kW average. A change in RF compression techniques resulted in only two klystrons needed pulsing per modulator at a reduced pulse width of 1.6 μsec or approximately 250 MW of the pulsed power and 80 kW of average powers. A prototype Design for Manufacturability (DFM) 8-pack modulator was under construction at the time of the change, so a redirection of modulator design was in order. To utilities the equipment which had already be fabricated, a hybrid modulator was designed and constructed using the DFM induction modulator parts and a conventional pulse transformer. The construction and performance of this hybrid two klystron Induction modulator will be discussed. In addition the next generation DFM induction modulator utilizing a ten turn secondary and fractional turn primary transformer well be presented.  
 
THP44 The Design and Performance of the Spallation Neutron Source Low-Level RF Control System linac, controls, feedback, coupling 703
 
  • M. Champion, M. Crofford, K. Kasemir, H. Ma, C. Piller
    ORNL/SNS, Oak Ridge, Tennessee
  • L. Doolittle, C. Lionberger, M. Monroy, A. Ratti
    LBNL, Berkeley, California
  • J. Power, H. Shoee
    LANL, Los Alamos, New Mexico
  The Spallation Neutron Source linear accelerator low-level RF control system has been developed within a collaboration of Lawrence Berkeley, Los Alamos, and Oak Ridge national laboratories. Three distinct generations of the system, described in a previous publication [1], have been used to support beam commissioning at Oak Ridge. The third generation system went into production in early 2004, with installation in the coupled-cavity and superconducting linacs to span the remainder of the year. The final design of this system will be presented along with results of performance measurements.

[1] M. Champion, et al, "The Spallation Neutron Source Accelerator Low Level RF Control System", Proceedings of the PAC2003 Conference, Portland, Oregon.

 
 
THP45 The Toshiba E3736 Multi Beam Klystron electron, cathode, gun, simulation 706
 
  • A. Yano, S. Miyake
    TETD, Saitama
  • Y.H. Chin
    KEK, Ibaraki
  • S.Y. Kazakov
    IHEP Protvino, Protvino, Moscow Region
  • A.V. Larionov, V.E. Teryaev
    BINP SB RAS, Protvino, Moscow Region
  A 10 MW, L-band multi beam klystron (MBK) for TESLA linear collider and TESLA XFEL has been under development at Toshiba Electron Tubes & Devices Co., Ltd. (TETD) in collaboration with KEK. The TESLA requires pulsed klystrons capable of 10 MW output power at 1300 MHz with 1.5 ms pulse length and a repetition rate of 10 pps. The MBK with 6 low-perveance beams in parallel in the klystron enables us to operate at lower cathode voltage with higher efficiency. The design work has been accomplished and the fabrication is under way. We are going to start conditioning and testing of prototype #0 in the beginning of June 2004. The design overview and the initial test results at the factory will be presented.  
 
THP46 Cable Insulation Breakdowns in the Modulator with a Switch Mode High Voltage Power Supply linac, power-supply, photon, simulation 709
 
  • A. Cours
    ANL, Argonne, Illinois
  The Advanced Photon Source modulators are PFN-type pulsers with 40 kV switch mode charging power supplies (PSs). The PS and the PFN are connected to each other by 18 feet of high-voltage (HV) cable. Another HV cable connects two separate parts of the PFN. The cables are standard 75 kV x-ray cables. All four cable connectors were designed by the PS manufacturer. Both cables were operating at the same voltage level (about 35 kV). The PS’s output connector has never failed during five years of operation. One of the other three connectors failed approximately five times more often than the others. In order to resolve the failure problem, a transient analysis was performed for all connectors. It was found that transient voltage in the connector that failed most often was subjected to more high-frequency, high-amplitude AC components than the other three connectors. It was thought that these components caused partial discharge in the connector insulation and led to the insulation breakdown. Modification of the PFN eliminated one HV cable and significantly reduced the AC components during the pulse. A connector with higher partial discharge inception voltage was chosen as a replacement.  
 
THP47 The RF-System for A High Current RFQ at IHEP cathode, power-supply, rfq, monitoring 712
 
  • Z. Zhang, J. Li, J. Qiao, X. Xu
    IHEP Beijing, Beijing
  The R&D of a high current proton RFQ is one of the most important research tasks of the Accelerator Driven Sub-critical system (ADS) basic research project. In preliminary research phase, the 352.2 MHz RF system will be operated in pulse mode. CERN kindly provided IHEP with some RF equipment. Because the given RF system was used for CW operation at CERN before, to apply them to our pulse mode operation, some modifications and improvements are necessary. We made some indispensable assemblies, and also did some tests and commissioning of every sub-system. At present, the initial high power conditioning of the klystron is finished, and output power can reach nominal value. A description of RF power system is given, in particularly, the performance of HV power supply, thyratron crowbar and capacitors, hard tube modulator and its control electronics, and klystron power conditioning are presented.  
Transparencies
 
THP49 The RF-Station Interlock for the European X-ray laser diagnostics, power-supply, monitoring, laser 718
 
  • T. Grevsmühl, S. Choroba, Ph. Duval, O. Hensler, J. Kahl, F.-R. Kaiser, A. Kretzschmann, K. Rehlich, U. Schwendicke, S. Simrock, S. Weisse
    DESY, Hamburg
  • H. Leich, RW. Wenndorff
    DESY Zeuthen, Zeuthen
  The RF-station interlock for the European X-ray laser will be based on a 19"- 3U crate incorporating a controller with the 32-bit RISC NIOS-processor (ALTERA). The main task of the interlock system is to prevent any damage from the components of the RF station and connected cavities. The interlock system must also guarantee a maximum time of operation of the RF stations which implies the implementation of self diagnostics and repair strategies on a module basis. Additional tasks are: collection and temporary storage of status information of the individual channels of the interlock system, transfer of this information to the control system, slow control functions (e.g. HV setting and monitoring) and control of inputs and outputs from and to other subsystems. In this paper we present the implementation using an ALTERA-FPGA running a 32-bit RISC NIOS-processor. Connection to the accelerator main control is provided by Ethernet using BSD-style socket routines based on ALTERA's plugs-library. The layout of the system is presented and first hardware components are shown.  
 
THP52 RF Reference Distribution System for the J-PARC Linac linac, power-supply, feedback, rfq 727
 
  • T. Kobayashi, E. Chishiro
    JAERI, Ibaraki-ken
  • S. Anami, S. Michizono, S. Yamaguchi
    KEK, Ibaraki
  J-PARC (Japan Proton Accelerator Complex) linac, which is 300 m long, consists of 324 MHz accelerating section of the upstream and 972 MHz section (as future plan) of the downstream. In the klystron gallery, totally about 50 RF source control stations will stand for the klystrons and solid-state amplifiers. The error of the accelerating field must be within ±1° in phase and ±1% in amplitude. Thus, the high phase stability is required to the RF reference for all of the low-level RF control systems and the beam monitor systems. This paper presents a final design of the RF reference distribution system for this linac. The RF reference (12 MHz) is distributed to all stations optically. Low-jitter E/O and O/E with temperature stabilizers are developed. The reference is optically amplified and divided into 14 transmission lines, and is delivered through PSOF (the phase-stabilized optical fiber), the temperature of which is stabilized by cooling water. Each of the transmitted signals is divided more into 4 signals by an optical coupler. Our objective for the phase stability of the reference aims at <±0.3° at a 972 MHz frequency.  
 
THP56 Control of the Low Level RF System for J-Parc Linac linac, feedback, proton, vacuum 739
 
  • S. Michizono, S. Anami, E. Kadokura, S. Yamaguchi
    KEK, Ibaraki
  • E. Chishiro, T. Kobayashi, .H. Suzuki
    JAERI, Ibaraki-ken
  A low level RF (LLRF) system for J-Parc linac generates RF and clock signals, drives a klystron, and stabilizes accelerating fields in the cavities. The LLRF system is controlled by two units: a programmable logic controller (PLC) and a compact PCI (cPCI) controller. Functions of the PLC are ON/OFF and UP/DOWN controls, and STATUS and ANALOG monitors. The PLC is locally operated by a touch panel, and remotely operated by an EPICS IOC with Ethernet communication. The cPCI controller is for RF feedback and feed-forward controls, including a cavity tuner control, and then, locally and remotely operated by communication with the PLC. On the other hand, RF waveform data, which are stored in the memory of DSP and CPU boards in the cPCI, are directory transmitted to an EPICS OPI by a request from EPICS.  
 
THP57 Digital Feedback System for J-Parc Linac RF Source feedback, linac, simulation, proton 742
 
  • S. Michizono, S. Anami, S. Yamaguchi
    KEK, Ibaraki
  • T. Kobayashi
    J-PARC, Ibaraki-ken
  At the proton linac of J-Parc (Japan Proton Accelerator Research Complex), an accelerating electric field stability of ±1% in amplitude and ±1° in phase is required for the RF system. In order to accomplish these requirements, a digital feedback system is adopted for flexibility of the feedback (FB) and feed forward (FF) algorism implementation. FPGAs are used for the real-time FB system. A DSP board is also utilized for data processing and communication between FPGAs and a crate control CPU (Host). The system was examined with the DTL cavity and it satisfies the stability specification. In this report, the digital rf system is described and operational stability is also summarized.  
 
THP58 Development of C-band High-Power Mix-Mode RF Window vacuum, resonance, acceleration, electron 745
 
  • S. Michizono, S. Fukuda, T. Matsumoto, K. Nakao, T. Takenaka
    KEK, Ibaraki
  • K. Yoshida
    MELCO, Hyogo
  High power c-band (5712 MHz) rf system (40 MW, 2 μs, 50 Hz) is under consideration for the electron-linac upgrade aimed for the super KEKB project. An rf window, which isolates the vacuum and pass the rf power, is one of the most important components for the rf system. The window consists of a ceramic disk and a pill-box housing. The mix-mode rf window is designed so as to decrease the electric field on the periphery of the ceramic disk. A resonant ring is assembled in order to examine the high-power transmission test. The window was tested up to the transmission power of 160 MW. The rf losses are also measured during the rf operation.  
 
THP59 Low Level RF Including a Sophisticated Phase Control System for CTF3 linac, collider, linear-collider, beam-loading 748
 
  • J. Mourier, R. Bossart, J. Nonglaton, I. Syratchev, L. Tanner
    CERN, Geneva
  CTF3 (CLIC Test Facility 3), currently under construction at CERN, is a test facility designed to demonstrate the key feasibility issues of the CLIC (Compact LInear Collider) two-beam scheme. When completed, this facility will consist of a 150 MeV linac followed by two rings for bunch-interleaving, and a test stand where 30 GHz power will be generated. In this paper, the work that has been carried out on the linac’s low power RF system is described. This includes, in particular, a sophisticated phase control system for the RF pulse compressor to produce a flat-top rectangular pulse over 1.4 μs.  
 
THP64 Waveguide Stub Tuner Analysis for CEBAF Application coupling, simulation, insertion, resonance 757
 
  • H. Wang
    Jefferson Lab, Newport News, Virginia
  • M. Tiefenback
    TJNAF, Newport News, Virginia
  Three-stub WR650 waveguide tuners have been used on the CEBAF superconducting cavities for two changes on the external Qs: increasing the Q from 6·106 to 8·106 on 5-cell cavities to reduce the klystron power at operation gradients and decreasing the Q from 2·107 to 8·106 on 7-cell cavities to ease the control system handling the Lorenz Force detuning. To understand the reactive tuning effects in the machine operations with beam current and mechanical tuning, a network analysis model was developed. The S parameters of the stub tuner were simulated by MAFIA and measured on the bench. We used this stub tuner model to study tuning range, sensitivity, frequency pulling as well as cold waveguide and window heating problems. Detailed experimental results will be compared against this model. Pros and cons of this stub tuner application will be summarized.