Acceleration performance of a 50-MHz split coaxial RFQ and the design of a 25.5-MHz prototype

Acceleration tests on a 50-MHz split coaxial RFQ (radio-frequency quadrupole) structure have been conducted at INS (the Institute of Nuclear Study at the University of Tokyo). The 2-m-long RFQ has accelerated protons from 2 to 60 keV. The experimental results concerning beam emittance and transmission efficiency agree with predictions of a computer simulation. Following this success, a 2-m-long 25.5-MHz prototype is being fabricated. The objectives of the present study are to establish a structure withstanding a high-power operation and to accelerate heavy ions with a charge-to-mass ratio larger than 1/30