Choroba, S.

Paper	Title	Page
MOPAN015	Compact Waveguide Distribution with Asymmetric Shunt Tees for the European XFEL	176
	V. V. Katalev, S. Choroba DESY, Hamburg
	In the European X-ray FEL 32 superconducting cavities (4 cryomodules with 8 cavities per module) are connected to one 10 MW multibeam klystron through a waveguide distribution system. The XFEL tunnel has limited space for the waveguide system and therefore a new more compact waveguide distribution has been developed. The waveguide distribution is based on a binary cell which consists of two circulators connected to a shunt tee with integrated phase shifters. Four binary cells are combined by three asymmetric pretunable shunt tees. The asymmetric shunt tees allow to change the RF power for each pair of cavities and to reach the maximum cryomodule gradient. In this paper we will present the status of the waveguide distribution system and report on the development of the different new waveguide components.
MOPAN018	Performance of the New Coupled Bunch Feedback System at HERA-p	185
	M. G. Hoffmann, S. Choroba, F. Eints, U. Hurdelbrink, P. Morozov, Y. Nechaev, J. Randhahn, S. Ruzin, S. Simrock, V. Soloviev DESY, Hamburg
	A longitudinal broadband damper system to control coupled bunch instabilities (LMBF) has been installed in the 920~GeV proton accelereator HERA-p at the Deutsches Elektronen-Synchrotron DESY in Q4/2005. The Feedback system was fully automated, in order to relieve the operator from manual control during system operation. During comissioning in Q1/2006 it turned out that the performance goals were reached and the noise is not as much a problem as expected. The proton bunch length is significantly reduced as is the stretching of the bunches over runtime. Without additional damping the bunch length is about 1.5~ns (FWHM) at the beginning of a typical luminosity run. With the new feedback system in operation the bunch length could be decreased to 1.0 ns at best. Although the bunches get longer during the luminosity run, the integrated luminosity gain is thus up to 5%. System optimization points were found in automatic gain adjustment during acceleration ramp, oscillation level triggering and timing of kicker pulse to bunch. We describe the commissioning of the multibunch feedback system and the adjustment procedures. A performace overview after one year of operation is given.
TUXC03	Design and Status of the XFEL RF System	841
	S. Choroba DESY, Hamburg
	The RF system of the European XFEL under construction at present at DESY in Hamburg, Germany, consists of 27 RF stations. At a later point of time the number might be increased to 31. The RF system provides RF power at 1.3GHz for the superconducting cavities of the main linear accelerator, the cavities of the injector and the RF gun. Each station consists of a 10MW multiple beam klystron, a HV pulse modulator, HV pulse cables, a pulse transformer, an interlock system, a low level RF system, a waveguide distribution system and a number of auxiliary power supplies. This paper describes the layout of the RF system and summarizes the design and status of the main high power components.
	Slides
WEPMN013	Testing of 10 MW Multibeam Klystrons for the European X-ray FEL at DESY	2077
	V. Vogel, S. Choroba, T. Froelich, T. G. Grevsmuehl, F.-R. Kaiser, V. V. Katalev, I. S. Sokolov, H. Timm DESY, Hamburg A. Cherepenko BINP SB RAS, Novosibirsk
	For the European XFEL project multibeam klystrons, which can produce RF power of 10 MW, at an RF frequency of 1.3 GHz, 1.5ms pulse length and 10Hz repetition rate, were chosen as RF power sources. So far three companies have produced this kind of new klystron. At DESY we installed a new test stand dedicated for testing this new type of RF power source. So far we have tested several tubes from Thales, Toshiba and CPI in our test stand. In this paper we give an overview of the test facilities and we summarize the current test results of the L-band multibeam klystrons (MBK).