• L.V. Kravchuk, V.V. Paramonov
  RAS/INR, Moscow
• A. Anisimov, M.V. Lalayan, A.Yu. Smirnov, N.P. Sobenin
  MEPhI, Moscow
• D. Churanov, E.V. Ivanov, S.V. Kutsaev, M. Urbant, A.A. Zavadtsev, D.A. Zavadtsev
  Nano, Moscow
• A. Donat, W. Köhler, M. Krasilnikov, J. Meissner, M. Pohl, J. Schultze, F. Stephan, G. Trowitzsch, R.W. Wenndorff
  DESY Zeuthen, Zeuthen
• C. Gerth, M. Hoffmann, M. Hüning
  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.

• J. Li, J.M. Qiao, X.A. Xu, Y. Yao, Z.H. Zhang, W. Zhou
  IHEP Beijing, Beijing
• Z.C. Mu
  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.

• A.R. Cours, G. Trento
  ANL, Argonne

A solid state Marx-based pulsed voltage supply is being developed at Argonne National Laboratory (ANL) with the capability of providing 300-kV pulses with 0.5-μs rise time, 1-μs fall time, 2-μs pulse flat top, and up to 10-Hz repetition rate. The supply is designed to operate a direct current (DC) thermionic prototype gun producing ≈ 0.1-μm beam emittance, a part of the ANL x-ray free-electron laser oscillator (XFELO) injector feasibility studies. The pulsed supply utilizes isolated gate bipolar transistor (IGBT) devices. Stage switching allows this supply to quickly charge the 200-pF gun capacitance and maintain 300-mA gun current during the pulse flat top. A second string of IGBT switches charges the stage capacitors and acts as a 'crowbar' to quickly remove high voltage from the gun at the pulse's fall time or during load arcing. We present an overview of the design and development of the XFELO injector DC gun pulsed power supply.

* Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH1137.

• C. Wiesner, L.P. Chau, H. Dinter, M. Droba, N.S. Joshi, O. Meusel, I. Müller, U. Ratzinger
  IAP, Frankfurt am Main

High intensity beams which are increasingly needed for a variety of applications pose new challenges for beam chopping. An ExB chopper system for proton beams of up to 200 mA and repetition rates of up to 250 kHz is under development at IAP. It will be tested and installed in the low energy section of the Frankfurt Neutron Source FRANZ at beam energies of 120 keV. The chopper consists of a static magnetic dipole field and a pulsed electric field in a Wien filter-type ExB configuration. The electric field temporarily compensates the magnetic deflection thus creating a proton pulse in forward direction, while the duty cycle of the electric field is minimized in order to reduce the risk of voltage breakdowns. Downstream of the chopper a septum will be used to separate the beams ensuring dumping outside the transport line in order to avoid uncontrolled power deposition and the resultant production of secondary particles. Numeric field optimizations and beam simulations including secondary electron effects are presented. Measurements of the high voltage pulse generator based on MOSFET technology and capable of generating 12 kV at 250 kHz as well as beam deflection experiments are shown.

• N. Nishimori
  JAEA, Ibaraki-ken
• R. Hajima, R. Nagai
  JAEA/ERL, Ibaraki
• Y. Honda, T. Miyajima, M. Yamamoto
  KEK, Ibaraki
• H. Iijima, M. Kuriki
  HU/AdSM, Higashi-Hiroshima
• M. Kuwahara, T. Nakanishi, S. Okumi
  Nagoya University, Nagoya
• T. Muto
  Tohoku University, School of Scinece, Sendai

An electron gun capable of delivering high current and high brightness electron beam is indispensable for next generation energy recovery linac light sources. A high voltage photocathode DC gun is a promising gun for such new light sources. It is however difficult to apply DC high voltage on a ceramic insulator with a rod supporting cathode electrode because of field emission from the rod. In order to mitigate the problem, we have employed a segmented insulator with rings which guard the ceramics from the field emission and recently succeeded in applying 500-kV on the ceramics for eight hours without any discharge. This high voltage testing was performed with a simple configuration without NEG pumps and electrodes. The next step is to repeat the same high voltage testing with a full configuration necessary for beam generation. We have designed electrodes for the maximum surface electric field not to exceed 11 MV/m at 500 kV while keeping the distance between the electrodes 100 mm. NEG pumps with a pumping speed of 7200 L/s have been installed in the gun chamber. A photocathode preparation system was connected to the gun chamber and beam generation is planned this summer.