Podlech, H.

Paper	Title	Page
MO302	Development of Room Temperature and Superconducting CH-Structures	28
	H. Podlech IAP, Frankfurt-am-Main
	H-mode cavities (IH-DTL, IH-RFQ, 4-Vane-RFQ) have been developed and operated successfully during the last decades for a large variety of applications in ion acceleration. At the IAP Frankfurt a new type of H-mode cavity, the CH-structure is under development. This multi cell drift tube cavity is operated in the H21 mode. Due to its mechanical stability, room temperature as well as superconducting cavities can be realized. The CH-structure is an excellent candidate for high power ion accelerators in the energy range from 5 to 100 MeV. The design status of the GSI 70 MeV, 70 mA proton injector DTL consisting of room temperature CH-structures is reported. Superconducting CH-structures can be used especially for cw operated linacs as designed for XADS, IFMIF or in nuclear physics projects. By using the KONUS beam dynamics and performing the particle simulations with the LORASR code it is possible to realize multi cell cavities without internal focusing lenses. A superconducting 352 MHz CH-structure (β=0.1) with 19 gaps has been built. We present the results of the first tests with this new cavity. The status of a PC version of the LORASR code will be reported.
	Transparencies
MOP12	KONUS Beam Dynamics Design of a 70 mA, 70 MeV Proton CH-DTL for GSI-SIS12	60
	R. Tiede, G. Clemente, H. Podlech, U. Ratzinger IAP, Frankfurt-am-Main W. Barth, L. Groening GSI, Darmstadt Z. Li IMP, Lanzhou S. Minaev ITEP, Moscow
	The future scientific program at GSI needs a dedicated proton injector into the synchrotron SIS, in order to increase the proton intensity of the existing UNILAC/SIS12 combination by a factor of 70, resulting in 7· 1012 protons in the synchrotron. A compact and efficient 352 MHz RFQ - CH-DTL combination based on novel structure developments for RFQ and DTL was worked out. For DTLs operated in an H-mode like CH-cavities (H210-mode), the shunt impedance is optimized by use of the KONUS beam dynamics. Beam dynamics simulation results of the CH-DTL section, covering the energy range from 3 to 70 MeV, with emphasis on the low energy front end are presented. Optimization aims are the reduction of emittance growth, of beam losses and of capital costs, by making use of the high acceleration gradients and shunt impedance values provided by the Crossbar H-Type (CH) structure. In addition, the beam dynamics design of the overall DTL layout has to be matched to the power limits of the available 352 MHz power klystrons. The aim is to power each cavity by one klystron with a peak rf power of around 1 MW.
MOP20	Design of the R.T. CH-Cavity and Perspectives for a New GSI Proton Linac	81
	Z. Li IMP, Lanzhou W. Barth, K. Dermati, L. Groening GSI, Darmstadt G. Clemente, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt-am-Main
	The CH-Structure has been studied at the IAP Frankfurt and at GSI for several years. Compared with the IH structure (H110-mode), the CH structure (H210-mode) can work at higher frequency (700 MHz) and can accelerate ions to higher energy (up to 150 AMeV). Detailed Microwave Studio (MWS) simulations were performed for this structure. Since a multi-gap cavity can be approximated as a quasi-periodic structure, it is possible to analyze one βλ/2-cell at an energy corresponding to the cavity center. Additionally, a reduced copper conductivity of 85% was assumed. Geometry variations with respect to rf frequency and shunt impedance can be performed rapidly by that method in the first stage of optimization. Effective shunt impedances from 100 MΩ/m down to 25 MΩ/m were obtained for the energy range from 5 AMeV to 150 AMeV by this method. The rf frequency was 350 MHz up to 70 MeV and 700 MHz above. A systematic analysis of the influence of the cell number in long CH cavities on the effective shunt impedance is presented. The possibility to apply this structure to a 70 mA, 70 MeV, 352 MHz proton linac for GSI is discussed.
TUP86	Coupler Development and Gap Field Analysis for the 352 MHz Superconducting CH-Cavity	477
	H. Liebermann, H. Podlech, U. Ratzinger, A.C. Sauer IAP, Frankfurt-am-Main
	The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under development at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. The reasonable frequency range is from about 150 MHz up to 800 MHz. A 19-cell, β=0.1, 352 MHz, bulk niobium prototype cavity is under development at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio simulations and measurements for the coupler development of the 352 MHz superconducting CH cavity. It will describe possibilities for coupling into the superconducting CH-Cavity. The development of the coupler is supported by measurement on a room temperature CH-copper model. We will present the first results of the measurements of different couplers, e.g. capacitive and inductive couplers, at different places of the CH Cavity.