Development of an Rfq-injector for a Therapy-synchrotron1

An accelerator facility for radiotherapy of cancer tumours with ions is proposed for the Radiologische Universitaetsklinik in Heidelberg. Design studies have been done for the synchrotron injector-complex with respect to construction and operation costs as well as to a save and simple handling of the machine [1]. After the source section and a LEBT path the beam will be injected into the RFQ at an energy of 8 keV/u to be accelerated to 400 keV/u with an electrode voltage of 70 kV and an expected power consumption of 100 kW. The RFQ layout, featuring a special electrode design, has been investigated with an extended version of the PARMTEQ code. The length of the RFQ will be approximately 1.55 m, the operation frequency is 216.816 MHz as in the following IH drift tube LINAC. For beam matching reasons, the combination of drift tubes with the RFQ electrodes at the high energy end is examined in detail by simulations with the MAFIA code as well as by measurements on a model set up. The IH structure represents the last step of acceleration before the injection into the synchrotron at 7 MeV/u. As the same injector should also deliver a 2 mA proton beam, space charge effects were examined by beam dynamic simulations.