• M. Hüning, M. Schmitz
  DESY, Hamburg
• C. Liebig
  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.

• 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.

• E.R. Harms, H.T. Edwards
  Fermilab, Batavia
• M. Hüning, E. Vogel
  DESY, Hamburg

A Third Hamonic/3.9 GHz superconducting RF module was recently installed in the FLASH facility at DESY. Ultra short bunches with high peak current are required to efficiently create high brilliance coherent light and these can be produced by means of a 2-stage transverse magnetic chicane bunch compression scheme coupled with off-crest acceleration. The long bunch tails and reduced peak current which result from the nonlinearities of the RF since wave can be eliminated by the addition of a 3rd harmonic RF system. Such a system can also allow for the creation of uniform intensity bunches of adjustable length necessary for seeded operation. We present here a summary of commissioning and early operating experience of the newly-installed device.