S. SETZER*, T. WEILAND (Darmstadt University of Technology), U. RATZINGER (GSI Darmstadt), S. MINAEV (ITEP Moscow)
The acceleration of heavy ions with IH structures is usually powered by tube driven rf transmitters. These are limited to about 1 MW in pulsed operation and at frequencies above 200 MHz. This paper reports about a development capable of providing about 2.5 MW rf power. An electron beam is directly coupled with one girder of an H-type structure by a two gap-array. In contrast to the bunch formation in klystrons a chopper technique is applied to get reasonable mechanical dimensions for the amplifier at frequencies below 400 MHz. A high perveance 40 A, 40 keV beam from a pierce-type electron gun is chopped in two steps by passage along the magnetic field from a solenoid and superposition of a transversal rf electric field (two harmonics) and of a transversal electrostatic field, respectively. The deflected particles are dumped in a depressed collector while the penetrating electron bunches are postaccelerated with about 300 kV before entering the H-type cavity. MAFIA-PIC-code simulations have demonstrated the efficiency of the suggested chopper array and have allowed to improve the design of this key element.
* Member of the Graduiertenkolleg (DFG GK-GRK 410/1)
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