• L. Lu, T. Hattori, N. Hayashizaki
  RLNR, Tokyo

A new type Linac, HSC (hybrid single cavity) linac for cancer therapy, which configuration combines RFQ (Radio Frequency Quadrupole) accelerating structure and DT (Drift Tube) accelerating structure is being finished designs and simulations now. This HSC linac design had adopted advanced power-efficiency-conformation, IH (Interdigital H) structure, which acceleration efficiency is extremely high in the low-middle energy region, and had also adopted most advanced computer simulation technology to evaluate cavity electromagnetic distribution. The study purposes of this HSC linac focus to design of injector linac for synchrotron of cancer radiotherapy facilities. Here, this HSC linac has an amazing space effect because of compact size by coupled complex acceleration electrode and integrated the peripheral device which is made operation easy to handle.

• T. Ishibashi, T. Hattori, N. Hayashizaki, L. Liang
  RLNR, Tokyo

High intensity heavy ion beam acceleration in the low energy region is one of the most difficult conditions to achieve, because the space charge effect is extremely strong. In order to generate a high intensity beam using linacs, we have to avoid beam loss by the space charge effect as much as possible. Multibeam acceleration has been proposed as a possible method of reducing the space charge effect. If one cavity could be used to accelerate several beams, a significant gain would be made in installation space and operational cost saving. In this study we look at a multibeam type radio frequency quadrupole (RFQ) linac in order to accelerate several beams using a single cavity. The RFQ electrodes are placed in an IH type cavity; This structure is known as a IH-RFQ linac. GSI in Germany proposed a multibeam type IH-RFQ linac with several beam channels in a single cavity. However, this multibeam type IH-RFQ linac has yet to be manufactured. We manufactured a 2-beam type IH-RFQ linac as a prototype of the multibeam type IH-RFQ. The linac outputs C²⁺ beam of 60 keV/u and 44 mA/channel in the design value. We will report about the beam acceleration test of the linac.

• Y. Takeda, Y. Irie, H. Kawakami, M. Oyaizu, I. Sugai, A. Takagi
  KEK, Ibaraki
• T. Hattori, K.K. Kawasaki
  TIT, Tokyo

Japan Proton Accelerator Research Complex (J-PARC) requires thick carbon stripper foils (200-500 ug/cm²) to strip electrons from the H^- beam supplied by the linac before injection into the Rapid Cyclic Synchrotron. A H^- beam of 181MeV energy is injected into the 3 GeV Rapid Cycling Synchrotron (RCS) with a pulse length of 0.5 ms, a repetition rate of 25 Hz, and an average beam current of 200 μA. The H^- ions are stripped into protons by a charge stripper foil in the injection section. For this high-energy and high-intensity beam, the conventional carbon stripper foils will be ruptured in a very short time. Thus, long-lived thick carbon stripper foils are needed to this high-power accelerator. For this purpose, we are described R and D of long-lived Hybrid Boron-mixed Carbon foils (HBC-foils) of 100 - 500 μg/cm² by arc discharge method. The preparation procedure is described and lifetime measurement by using a 3.2MeV Ne⁺ DC beam of 2-3 μA are reported.