• A. Bechtold, U. Bartz, M. Heilmann, P. Kolb, H. Liebermann, O. Meusel, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, C. Zhang
  IAP, Frankfurt am Main
• G. Clemente
  GSI, Darmstadt

Funding: Work supported by BMBF
The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum will comprise a short 175 MHz linac sequence consisting of a 1.4 m long 700 keV 4-rod type RFQ followed by a 50 cm IH-DTL for proton acceleration up to 2 MeV. The beam current is 200 mA at pulsed and 30 mA at cw operation. The aim is to have a very compact device driven by only one rf amplifier to reduce costs and required installation space. A coupling between the RFQ and the IH resonators by means of a galvanic connection is foreseen, which is realized by two brackets going right away through a common partitioning end flange lid. The accelerators could also be driven separately by just removing the brackets. The distance between the end of the RFQ electrodes and the middle of the first DTL gap is only 5 cm, there is no additional beam optics in between. Preliminary beam dynamics and rf simulations have been carried out together with accompanying measurements on rf models.

• O. Meusel, A. Bechtold, L.P. Chau, M. Heilmann, H. Podlech, U. Ratzinger, K. Volk, C. Wiesner
  IAP, Frankfurt am Main

The Frankfurter neutron source at Stern-Gerlach-Zentrum (SGZ) uses a proton injector as a driver for the 7Li(p,n) neutron production. A volume type ion source will deliver a 100 keV, 200 mA proton beam continuously. It is intended to use a LEBT section consisting of four solenoids to transport the beam and to match it into the acceptance of the RFQ. A chopper system between solenoid 2 and 3 will provide beam pulses with a length of about 100 ns with a repetition rate of 250 kHz. The RFQ and the following IH drift tube LINAC will be coupled together to achieve an efficiency beam acceleration. Furthermore only one power amplifier will be needed to provide the rf power for both accelerator stages. The Mobley type bunch compressor will merge 7 micro-bunches formed in the accelerator module to one single 1ns bunch with an estimated peak current of about 8.6 A. A rebuncher will provide the post acceleration at a final beam energy adjustable between 1.8 and 2.4 MeV. The whole injector suffers from the high beam intensity and therefore high space charge forces. It will gives the opportunity to develop new accelerator concepts and beam diagnostic technics.

• H. Podlech, M. Amberg, A. Bechtold, M. Busch, F.D. Dziuba, U. Ratzinger, C. Zhang
  IAP, Frankfurt am Main

Funding: GSI, BMBF contr. No. 06F134I, EU contr. No. 516520-FI6W, RII3-CT-2003-506395, EFDA/99-507ERB500CT990061
Worldwide there is an increasing interest in new high intensity proton and ion driver linacs with beam powers up to several MW. A very challenging part of these accelerators is the low and medium energy section up to 100 MeV. Depending on the duty cycle room temperature or superconducting options are favoured. In both cases the Crossbar-H-mode (CH)-structure, developed at the IAP in Frankfurt is an excellent candidate. Room temperature as well as superconducting prototype cavities have been developed and tested successfully. A superconducting 19 cell low energy (beta=0.1) CH-cavity at 360 MHz reached effective gradients of 7 MV/m corresponding to an accelerating voltage of 5.6 MV. This cavity could be used for high intensity, cw operated linacs like accelerator driven systems (ADS, EUROTRANS) or the international fusion material irradiation facility (IFMIF). Additionally, the new proton injector for FAIR (325 MHz, 70 mA, 70 MeV) will use room temperature CH-cavities. Recent developments of this new type of a multi-cell drift tube cavity, beam dynamics issues and the tests of the prototypes will be presented.