DESIGN AND CONSTRUCTION OF HEAVY-ION RFQ LINAC WITH EFFECTIVE ACCELERATION STRUCTURE

At the Tokyo Institute of Technology, generating a plasma with a heavy ion beam has been studied for basic research on inertial fusion and a heavy-ion pumped laser. These experiments require a high intensity and high brightness beam. An 80 MHz heavy-ion RFQ linac is being constructed to meet the requirements. This linac accelerates particles with a charge to mass ratio (q/A) greater than 1/16 from 5 keV/amu up to 214 keV/amu. Two-dimensional (2D) machining is applied for cutting of the RFQ vane-tips. We simulated the beam optics including effects of higher order harmonies in the intervane potential (H. Deitinghoff, A. Schempp, H. Klein and 0. Pan, Particle Acc. 37-38 (1992) 47; Chen Chia-Erh, Fang Jia-Xun, Li Weigo, Pan Oujia, Lu Yuanfong, Li Deshan, Wang Lishan, Yu Maolin, H. Deitinghoff, A. Schempp and H. Klein, Proc. European Particle Acc. Conf. (1992) p. 1328) for optimization of the vane parameters. In order to increase the acceleration efficiency, synchronous phase was gradually raised from -30-degrees to -20-degrees in the accelerator section of the cavity. The expected beam transmission is 91.8% for a beam current of 0 mA and 68.4% for 10 mA.