DESY, Hamburg
Uni HH, Hamburg
At present the Linac II at DESY consists of a 6A/150kV DC electron gun, a 400 MeV primary electron linac, a 800 MW positron converter, and a 450 MeV secondary electron/positron linac. To improve the maintainability of the system and to reduce operational risks the original 150kV diode gun will be replaced by a 100kV triode. Together with the gun the whole injection system will be upgraded and optimized for minimal load on the converter target and primary linac. The core of the new injector are a 5MeV standing wave/travelling wave hybrid structure and a magnetic energy filter. Simulations show that With 6A DC current up to 3.7A can be bunched into 20° of the 2.998 GHz RF. This phase range is narrow enough to fit after on-crest acceleration into the energy acceptance of the following accumulator ring PIA.
KEK, Ibaraki
In order to improve the positron beam intensity needed for super KEKB project, it was decided to replace the present S-band structures in the positron capture section by a new L-band (1298MHz) accelerator system. A 2m long TW structure of 12MV/m gradient is now under idesign process while a 40MW klystron will be delivered in summer. After the klystron testing, a single L-band accelerator unit will be constructed for the structure study. The study is scheduled in next spring to operate the structure under solenoidal magnetic focussing field.
Diamond, Oxfordshire
The Diamond Light Source injection system consists of a 100MeV linac and a 3GeV full-energy booster. The injector is used to fill the storage ring from empty and to provide beam for a 10 minute top-up cycle. The high power RF for the linac is generated by two S‑band klystrons, the first powering a buncher and accelerating structure, and the second feeding a second accelerating structure. With the klystrons feeding the two accelerating structures independently, a failure in the klystron or modulator feeding the lower energy structure and bunchers renders the linac, and hence the injection system as a whole, inoperable. In order to address this problem, the RF feed to the linac has been reconfigured to enable either klystron to power the first structure and bunchers; this has involved a rebuild of the waveguide network in the linac vault to include two four-way S-band switches, and the development of a lower energy operating mode for the linac, booster and linac-to-booster transfer line. Details are presented in this paper of the installation and test of the switching network, and the first results are reported of the new operating mode.
CERN, Geneva
Ankara University, Faculty of Engineering, Tandogan, Ankara
PSI, Villigen
JAI, Oxford
INFN/LNF, Frascati (Roma)
In CLIC very tight tolerances exist for the phase and amplitude stability of the main and drive beam. In this paper we present the status of the CLIC beam phase and amplitude stabilisation concept. We specify the resulting tolerances for the beam and technical equipment and compare to first measurements.
KEK, Ibaraki
Distributed RF Scheme (DRFS) was proposed for International Linear Collider (ILC) as a new HLRF scheme. After the ITRP recommendation, ILC technology was chosen to be superconducting technology and basic design was discussed and reported in the RDR on 2007. Aiming for the cost reduction, there have been proposed many ideas and summarized as SB2009 proposal. DRFS is the one of these proposals, and it is linked to the single tunnel plan. DRFS employs many small klystrons (750kW output power) which feed power to two superconducting cavities. 13 modulating anode klystrons are operated by a DC power supply and a modulating anode pulser. All required components are installed in a tunnel and therefore this scheme is a complete single tunnel layout. DRFS was proposed in 2008 and thereafter it has been discussed in web-ex meeting and GDE workshop. In this conference, concept and detailed design of DRFS are presented including the availability and operability. In order to show the feasibility of DRFS, KEK has a plan of demonstration employing the DRFS with two klystrons in the S1 global in the end of 2010. Presenter also discussed pros and cons comparing with the competing proposed scheme.
KEK, Ibaraki
The international linear collider (ILC) project is about to meet the technical design phase 2, of which the goal is to establish a realistic design by the end of 2012. Single-tunnel accelerator configuration is one of the most essential improvements to reduce the construction costs. The original design involves two tunnels which house the accelerator cavities and the power supplies separately, having such advantages as we can enter the power-supply tunnel even during beam operation. Although the single tunnel configuration sacrifices these functions, it saves big tunnel construction costs. The Asian team is studying a regional single-tunnel accelerator configuration to match the Asian site feature in conjunction with a compact high-level RF scheme called distributed RF system (DRFS). The design concepts have been developed by a conventional facility working group in the advanced accelerator association (AAA) which involves a collaboration among academic, industrial, and political communities in Japan. Not only cost reduction but also functional impacts of tunnel configuration on things such as life safety are discussed in this paper.
POSTECH, Pohang, Kyungbuk
KAPRA, Cheorwon
NFRI, Daejon
PAL, Pohang, Kyungbuk
An intense L-band electron linac is now being commissioned at ACEP (Advanced Center for Electron-beam Processing in Cheorwon, Korea) for irradiation applications. It is capable of producing 10-MeV electron beams with the 30-kW average beam power. The constant-impedance accelerating structure is operated under fully-beam-loaded condition with the RF power of peak 25 MW and the beam current of 1.45 A. The total attenuation coefficient of the structure is 0.17 and the RF filling time is 0.9 μs along the 2.3-m accelerating structure. To suppress the energy spread due to the transient beam loading effect, we consider three methods: modulating the beam current amplitude, modulating the RF amplitude, and adjusting the beam injection time. In this paper, we calculate the transient beam energy numerically for the above cases. We also propose the actual compensation method.
CERN, Geneva
CEA, Gif-sur-Yvette
INFN/LASA, Segrate (MI)
In the framework of the preparatory phase for the luminosity upgrade of the LHC (SLHC-PP ) it is foreseen to characterize two superconducting RF cavities and demonstrate compliance of the required SPL field stability in amplitude and phase using a prototype LLRF system. We report on the preparation for testing of two super-conducting low-beta cavities at 50 Hz pulse repetition rate including the setting-up of the low level RF control system to evaluate the performance of the piezo-tuning system and cavity field stability in amplitude and phase. Results from tests with 50 Hz pulse repetition rate are presented. Simulations of the RF system are used to predict the necessary specifications for power and bandwidth to control the cavity field and derive specifications for the RF system and its control.
This project has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under the Grant Agreement no 212114
KEK, Ibaraki
CERN, Geneva
Several types of X-band high power loads developed for several tens of MW range were designed, fabricated and used for high power tests at X-band facility of KEK. Some of them have been used for many years and some show possible deterioration of RF performance. Recently revised-design loads were made by CERN and the high power evaluation was performed at KEK. In this paper, the main requirements are recalled, together with the design features. The high power test results are analysed and presented.
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
For 400-MeV upgrade of the J-PARC Linac, ACS (Annular Coupled Structure) cavities, which are driven by 972-MHz RF, will be installed. The ACS cavity has complicated structure. Its Q-value is very low and the operation frequency is tree times higher in comparison with that of the SDTL cavity. So the stabilizing control of the ACS accelerating field will be more difficult than present 324-MHz RF system. Further more the chopped beam loading compensation is required. Especially, the debuncher will be located very far from the klystron, then the feedback loop delay will be about 1.5 us. This presentation will show the simulation results of the feedback control of the ACS cavity field including long loop delay and the effect of the chopped beam loading.
ORNL, Oak Ridge, Tennessee
ORNL RAD, Oak Ridge, Tennessee
The Spallation Neutron Source (SNS) has been operating since the first neutrons were produced on April 29, 2006. During the last several years the beam energy has been methodically ramped-up and outlying issues solved to improve system reliability. During the beam studies a temperature dependence has been discovered with the Low-Level RF systems. The effect is small but readily observable as increased beam losses. The temperature dependence has been studied both in the accelerator and in the laboratory and the sensitive components identified. A prototype solution that replaces the temperature dependent components of the Low-Level RF System has been designed and is in initial testing. Preliminary results of the laboratory tests have been encouraging. Accelerator tests are planned after installation during the December 2010 maintenance cycle.
JAEA/LINAC, Ibaraki-ken
The J-PARC (Japan Proton Accelerator Research Complex) accelerator comprises the 400-MeV injector linac (at present 181 MeV), the 3-GeV Rapid-Cycling Synchrotron (RCS) and the 50-GeV Main Ring (MR). The 3-MeV RFQ, the 50-MeV DTL and the 181-MeV Separated-type DTL have been operated in the linac for experimental users. The 400-MeV energy upgrade of the linac started from March 2009. The ACS (Annular Coupled Structure) cavities, the RF sources, the beam monitors and the utilities are in production. Although some components are prepared in the annual summer shutdown separately, the all cavities will be installed and commissioned for 6 months from July 2012. In this paper, we present the current status and the preliminary results of the energy upgrade.
IHEP Beijing, Beijing
Work on the Chinese Spallation Neutron Source (CSNS) has been progressing well, including successful prototyping of some of the key components of the facility. The source incorporates an H- linac, with an output energy upgradable from 81 to 250 MeV. The status of the project will be described.
PSI, Villigen
The Swiss FEL linac consists of a 450 MeV S-band injector and of a main linac at the C-band frequency (5.712 GHz) aiming at a final energy of 5.8 GeV. The main linac is composed of 26 RF modules. Each module consists of a single 50 MW klystron and its solid-state modulator feeding a pulse compressor and four accelerating structures. The two-meter long C-band accelerating structures have 110 cells, including the two coupler cells, and operate with a 2π/3 phase advance. We report here on RF studies performed on the accelerating structures with different cell topologies and on the pulse compressor where a Barrel-Open Cavity (BOC) design is adopted. The power requirements for the different accelerating structures with the single and two-bunch operation are also presented.
ELETTRA, Basovizza
FERMI@Elettra is a single-pass FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third-generation synchrotron radiation facility Elettra in Trieste, Italy. The first electron beam from the photocathode electron rf gun and injector system was extracted in August 2009. Commissioning and installation of the remaining linac and linac systems are continuing and will alternate through this year . The linac is based on normal conducting S-band technology. It uses fifteen 3 GHz 45 MW peak RF power plants powering the gun, the accelerating structures, and the RF deflectors, and when completed will be able to deliver greater than 1.5 GeV electron beams to the FEL undulator system. This paper provides a summary of the installation activities and discusses the performances results of the main subassemblies both during the initial checkouts and through the commissioning of the accelerator.
KEK, Ibaraki
JAEA/ERL, Ibaraki
ISSP/SRL, Chiba
Future light sources based on the Energy Recovery Linac (ERL) are expected to bring innovation to the synchrotron radiation (SR) science. Our Japanese collaboration team plans to construct a 5-GeV ERL which can produce super-brilliant and ultra-short pulses of SR as well as can be a driver for a proposed X-ray free-electron laser oscillator (X-FELO). In order to establish the key technologies for the ERL, we are conducting aggressive R&D efforts. Concerning our high-brightness photocathode DC electron gun, we succeeded to apply a DC high voltage of 500 kV through a support rod. Both cryomodules for the injector and the main-linac are also under development. In order to demonstrate reliable operations of such key technologies, we plan to construct the Compact ERL (cERL) at KEK. During FY2009, we prepared the infrastructure for the cERL which includes renovation of the building (the East Counter Hall), renovation of cooling-water system and electrical substation, installation of liquid helium refrigerator, and installation of a part of the rf source. In this paper, we present up-to-date status of the ERL and the Compact ERL projects in Japan.
RAS/INR, Moscow
MEPhI, Moscow
Nano, Moscow
DESY Zeuthen, Zeuthen
DESY, Hamburg
Transverse Deflecting Systems are designated for longitudinal beam diagnostics of ultra-short electron bunches in modern FEL projects. At the European XFEL, Transverse Deflecting Systems are foreseen at three locations. A prototype of the TDS in the injector of the European XFEL will be installed at PITZ which is identical in terms of deflecting structure, low-level RF system and powerful RF hardware. This PITZ TDS has the aim to prove the required performance for all TDS subsystems as well as serve as a diagnostics tool for PITZ. Results of the test cells measurements of a S-band travelling wave structure are presented, showing very good agreement with calculated parameters. RF power supply system, including 3 MW klystron and other RF hardware, is described. Solid state 130 kV Marx modulator has been developed for the klystron feeding. 10 kV module of the modulator has been built and tested. The modulator allows for high voltage shutdown within pulse.
JASRI/SPring-8, Hyogo-ken
RIKEN/SPring-8, Hyogo
The injector of the 8 GeV linac generates an electron beam of 1 nC, accelerates it up to 30 MeV, and compresses its bunch length down to 20 ps. Even slight RF instability in its multi-stage bunching section fluctuates the bunch width and the peak current of an electron beam and it accordingly results in unstable laser oscillation in the undulator section. The acceptable instabilities of the RF fields in the cavities, which permit 10% rms variation of the peak beam current, are only about 0.01% rms in amplitude and 120 fs rms in phase according to beam simulation. The long-term RF variations can be compensated by feedback control of the RF amplitude and phase, the short-term or pulse-to-pulse variations, however, have to be reduced as much as possible by improving RF equipment such as amplifiers. Thus we have carefully designed and manufactured the RF cavities, amplifiers and control systems, giving the highest priority to the stabilization of the short-term variations. Components of the injector will be completed by the end of the May 2010, and the injector will be perfected in the summer 2010. We will present the performance of the completed devices in the conference.
SLAC, Menlo Park, California
With the growing demand for FEL light sources, cost issues are being revaluated. To make the machines more compact, higher-frequency room-temperature linacs are being considered, in particular, ones using C-band (5.7 GHz) rf technology where 40 MV/m gradients are possible. In this paper, we show that an X-band (11.4 GHz) linac using the technology developed for NLC/GLC can provide an even lower cost solution. In particular, stable operation is possible at gradients of 100 MV/m for single bunch operation, and 70 MV/m for multibunch operation. The concern of course is whether the stronger wakefields will lead to unacceptable emittance dilution. However, we show that the small emittances produced in a 250 MeV, low bunch charge, LCLS-like S-band injector and bunch compressor can be preserved in a multi-GeV X-band linac with reasonable alignment tolerances.
ELETTRA, Basovizza
FERMI@Elettra is a soft X-ray, fourth generation light source facility in the last phase of its construction stage at the Elettra Laboratory in Trieste, Italy. It will be based on a seeded FEL, driven by the existing normal conducting linac that is presently expected to operate at 1.5 GeV. Two differet FEL lines will produce very short coherent photon pulses (25-200 fs) in the UV snd soft X-ray region (100-4 nm). FEL1 will cover 100-20 nm, FEL2 20-4 nm. Here a possibility to extend the FERMI spectral range capability down to the water window (1.0-2.0 nm) is presented. The suggested upgrading foresees the increase of the linac energy up to 2.4-2.5 GeV, leaving untouched the existing undulator chains and the overall length of the accelerator.
KAERI, Daejon
A 100MeV proton accelerator is developed by the Proton Engineering Frontier Project (PEFP). As a front part, a 20MeV linac has been installed and operated at Korea Atomic Energy Research Institute (KAERI) site. Among the components for the 100MeV accelerator, some parts were installed and tested by using 20MeV linac. One modulator for a 100MeV linac was installed to drive two klystrons simultaneously which were used for a 20MeV linac. Various operating parameters such as a long term voltage fluctuation and control performance are checked during operation. Also a LLRF system for 100MeV linac which was modified from the 20MeV system was installed and tested. In this paper, the operation characteristics of the 20MeV linac are presented especially from the viewpoint of the newly installed components such as a modulator and LLRF system.
TUB, Beijing
The Compact Pulsed Hadron Source (CPHS) system has been proposed and designed by the Department of Engineering Physics of Tsinghua University in Beijing, China. It consists of an accelerator front-end'a high-intensity ion source, a 3 MeV radiofrequency quadrupole linac (RFQ), and a 13 MeV drift-tube linac (DTL), a neutron target station, and some experimental stations. In our design, both RFQ and DTL share a single klystron which is capable of 2.5 MW peak RF power and a 3.33% duty factor. The 325 MHz klystron contains a modulating anode and has a 100 kW average output power. Portions of the RF system, such as pulsed high voltage power source, modulator, crowbar protection and RF transmission system are all presented in details in this paper.
LANL, Los Alamos, New Mexico
LANSCE has been the centerpiece of large-scale science at Los Alamos National Laboratory for many decades. Recently, funding has been obtained to ensure continued reliable operation of the LANSCE linac and to allow planning to enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges. MaRIE will provide the tools scientists need to develop next-generation materials that will perform predictably and on-demand for currently unattainable lifetimes in extreme environments. The MaRIE facility is based on a high-power upgrade to the existing LANSCE proton linac, a new electron linac and associated X-ray FEL to provide additional probe beams, and new experimental areas. A conceptual description of this new facility and its requirements will be presented.
CERN, Geneva
Linac4 is a 160 MeV normal-conducting H- linear accelerator which is being built at CERN in the frame of a program for increasing the luminosity of the LHC. The project started in 2008 and delivery of beam to the CERN accelerator chain is foreseen from early 2015. The new linac will be housed in an underground tunnel close to the present Linac2; a surface building will house RF and other infrastructure. The civil engineering work started in October 2008 will be soon completed. Installation of the infrastructure will take place in 2011, and from 2012 will be installed the main machine elements. The ion source is presently operational on a test stand, where it will be followed in 2011 by a 3 MeV RFQ under construction in the CERN workshops. Prototypes of the three different types of accelerating structures have been tested; construction of the 22 accelerating cavities has started, supported by a network of agreements with external laboratories and institutions. Commissioning will take place in stages, starting from January 2013. Starting in March 2014 is foreseen a six-month reliability run, in preparation for its role as the new source of particles for the CERN complex.
PAL, Pohang, Kyungbuk
Since its completion in 1993, the PLS (Pohang Light Source) linear accelerator has been operated as the full energy injector to the PLS storage ring - a 2.5-GeV 3rd generation light source in Korea. After successful services for more than 15 years to the Korean synchrotron radiation users' community, the PLS is now being upgraded to meet ever-increasing user demands for brighter lights. The PLS-II, the major upgrade program to the PLS, is to increase the beam energy to 3 GeV, changing the storage ring lattice to accommodate large number of insertion devices with lower emittance, and to have the top-up injection as the default operating mode. In order to achieve high injection efficiency (> 80%), beam qualities including the energy spread, pulse length, and jitters in bunch arrival times to the storage ring rf bucket have to be reduced. After successful upgrade of the PLS linac one could further exploit its potential by, for example, implementing high-brightness electron source, which would open up new possibilities with the facility
CERN, Geneva
This talk gives an overview of recent results and future prospects on RF sources for linac applications, including klystrons, magnetrons and modulators.
CERN, Geneva
BNL, Upton, Long Island, New York
During the past 2 years the Superconducting Proton Linac (SPL) study has grown into an international collaboration with the goal of optimising the architecture of a pulsed superconducting (SC) high-power proton linac. This effort includes the study and prototyping of major technical components, such as SC high-gradient cavities, power couplers, the RF distribution system, HOM couplers, cryo-modules, focusing elements, etc. Even though the effort is driven by CERN specific needs, the established design principles are valid for a range of superconducting linac projects. In this paper we report on the latests decisions concerning the machine architecture and on the ongoing R&D effort for technical components.
LANL, Los Alamos, New Mexico
SLAC, Menlo Park, California
STI, Santa Barbara, California
In order to overcome the theoretical limit of ~200 mT peak surface magnetic field for niobium SRF cavities, an idea of coating multi-layer thin film superconductors separated with thin dielectric layers has been suggested. We are testing MgB2, NbN and NbC as candidates for the realization of this idea. The results of surface characterization, Auger depth profile, DC magnetization measurements with SQUID, low- and high-field measurements with a TE013-like mode copper cavity coupled with a 11.4 GHz short-pulse Klystron will be presented.
IHEP Beijing, Beijing
Institute of High Energy Physics, CAS, Bejing
China Spallation Neutron Source (CSNS) is determined to be constructed in Dongguan, Guangdong province of south China. Now its design and R&D are in progress in IHEP, Beijing. The 324 MHz rf linac is designed with beam energy of 81 MeV and a peak current of 30 mA. In the klystron gallery, five klystron power sources will be used to power the RFQ and the four DTL tanks, and three solid state RF amplifiers will drive two MEBT bunchers and a LRBT debuncher. Now we have already made some progress with some key technologies for linac RF system. The digital low level RF control prototype was already developed and successfully applied in beam commissioning of the ADS (Accelerator Driven Sub-critical system) 3.5MeV RFQ accelerator at peak beam 44.5mA, beam duty 7.15%. A proposed new type of power supply, 100Hz ac series resonance high voltage power supply, passed acceptance test and a satisfactory test results was obtained. R&D of crowbar and modulator has gotten preliminary performance test data.
CERN, Geneva
Linac4 is a linear accelerator for negative Hydrogen ions (H-) which will replace the old Linac2 as linear injector for the CERN accelerators. Its higher energy of 160 MeV will give increased beam intensity in the downstream machines. Linac4 is about 100 m long, normal-conducting, and will be housed in a tunnel about 12 m below ground. The Linac4 tunnel will be connected to the existing chain of accelerators and can be extended to the new injection chain. The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new 2.8 MW klystrons of all operating at a frequency of 352.2 MHz. The integration of the RF power system in the building is presented. The technical specifications and the performance of the various high-power elements are discussed, with emphasis on the required retuning of the LEP klystrons. The power distribution system including the power splitting requirements are also described.
TRIUMF, Vancouver
A 500 kW electron linear accelerator is being proposed at TRIUMF for radioactive ion beam production to support existing rare isotope facility. Present design consists of 100 keV thermionic gun, a normal conducting buncher, an injector module and main linac modules. The design energy is 50 MeV with 10 mA beam current. The linac will operate in cw mode using 1.3 GHz superconducting technology. The injector cryomodule (ICM), uses a nine-cell TESLA type cavity operating at 2 degree Kelvin. The front end of the ICM has a room temperature buncher and also has two superconducting capture cavities which are housed in the same cryomodule as the accelerating multi-cell cavity. Solid state amplifiers are proposed to be used for the buncher and the capture cavities. A 30 kW 1.3 GHz IOT, operating at cw will be used to drive the nine-cell cavity of the ICM. The rf power will be divided into two equal parts and fed to two TTF III type couplers. The same couplers are intended to be used for the remaining accelerator cavities of the e-linac. The e-linac is being proposed to be built in stages. High power Klystrons are to be used to provide rf power to the accelerating cavities.
KEK, Ibaraki
JAEA, Ibaraki-ken
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
This report will describe the present status of the power supply systems (PS systems) for the klystrons in the J-PARC (Japan Proton Accelerator Research Complex) linac. The technical specification, the operating experience, and the upgrade plan, of the PS systems will be presented in this report. Now the energy of the J-PARC linac is 181MeV, and the linac includes twenty 324MHz klystrons. In 2012, the energy will be upgraded to 400MeV, and the linac will include twenty 324MHz klystrons and twenty-five 972MHz klystrons. The klystrons are the modulating-anode types. The PS systems include the High voltage DC power supplies (DCPSs) and the anode-modulators. One DCPS drives one or four klystrons, and one anode-modulator drives one klystron.
KEK, Ibaraki
Fermilab, Batavia
The X-band pulse compression system has been developed for the high gradient experiment of the accelerating structure in the new X-band test facility (Nextef). The one channel circular polarized traveling wave delay line was selected to obtain the higher RF compression efficiency under limited delay line length and the easier operation than the cavity chain type. This delay line of the circular waveguide is also frequently used for the C-band feed line from the modulator floor to the accelerator test floor. Thus the delay line is tilted and has the limited length of around 20m. It is designed to obtain the three times compressed power which has the pulse duration of 150 ns. Further we also proceed the upgrade plan using the TE21 mode to double the pulse duration. In this paper, the design overview of this pulse compression system and the RF components including the mode launcher and the TE11-TE21 reflector will be presented.
DESY Zeuthen, Zeuthen
DESY, Hamburg
The European XFEL, an X-ray free electron laser, is planned as an European project with a strong connection to the DESY research center in Hamburg. Construction started in summer 2007 and commissioning will begin in 2014. The LINAC of the XFEL will incorporate 27 RF stations to supply the RF power required by the superconducting cavities. In order to generate this power (10MW at 1.3GHz) HV pulse modulators are required. Each modulator has to supply 12kV pulses at 1.6kA for 1.7ms pulse duration and at 10Hz nominal repetition rate. The repetition rate can be increased to 30Hz keeping the average power of the 10Hz operation. Although experience exists for FLASH with modulators constructed and built by one company two additional companies have been selected and contracted to design and to build additional prototypes of modulators according to the XFEL requirements. A test stand setup has been prepared at DESY, Zeuthen Site, in order to test and to operate these protoypes under similar conditions as at the XFEL. The presentation describes the Modulator Test Facility at DESY (Zeuthen Site) and presents and discusses test results of the modulator prototype from Thomson Multimedia.
DESY, Hamburg
The FLASH RF system consists of several RF stations, which provide RF power up to 10MW at 1.3GHz, 1.3ms and 10Hz repetition rate, each, for the superconducting cavities and the RF gun of the FLASH linear accelerator. During the last upgrade of the FLASH facility several modifications have been made also to the RF system. The oldest RF stations were constructed and manufactured by FNAL more than 15 years ago and have been replaced. Since one additional superconducting accelerator module has been added and one superconducting module and the RF gun have been replaced, modification and rearrangement of the RF waveguide distributions were required. An XFEL type waveguide distribution for the new accelerator module ACC7 and a distribution without individual phase shifters for the exchanged module ACC1 have been installed. A new waveguide distribution for the RF gun allows phase tuning by changing the gas pressure in the waveguides. It will also allow supply the RF gun by a 10MW multi beam klystron instead of the still used 5MW single beam klystron at a later point of time.
SLAC, Menlo Park, California
The SLAC National Accelerator Laboratory is leading an effort to design a prototype Marx modulator to meet the ILC klystron modulator specifications; a 120 kV (± 0.5%), 140A, 1.6 ms pulse at a 5 Hz prf. A first generation prototype, the P1 Marx, has been developed and is undergoing life testing*. The design of a second-generation Marx, P2, has been completed and most sub-systems have been tested**. The P2 advances the Marx topology demonstrated by the P1; eliminating single-point failures, incorporating advanced diagnostics/prognostics, and optimizing engineering margins to improve system availability. The P2 consists of 32 cells, which are individually regulated at an output of up to 4kV. This is in contrast to the P1 Marx which is collectively regulated by a series "Vernier" Marx. The 30 of 32 cell redundancy allows for up to two cell failures without degrading the modulator output. Failed cells can be quickly replaced and remotely-serviced. This paper presents the design of the P2 Marx. Specific topics discussed include the control architecture, mechanical layout, and power electronics design. Experimental results of both a single and array of cells are presented.
* C. Burkhart, et al., "ILC Marx modulator development status," LINAC, 2008.
** K. Macken, et al., "Towards a PEBB-Based Design Approach for a Marx-Topology ILC Klystron Modulator," PAC, 2009.