Instability of mismatched beam in the proton linear accelerator

Research Project

Project/Area Number	09640348
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	素粒子・核・宇宙線
Research Institution	KYOTO UNIVERSITY
Principal Investigator	INOUE Makoto Kyoto University, Institute for Chemical Research, Professor, 化学研究所, 教授 (90028176)
Project Period (FY)	1997 – 1998
Project Status	Completed (Fiscal Year 1998)
Budget Amount *help	¥1,400,000 (Direct Cost: ¥1,400,000) Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000) Fiscal Year 1997: ¥800,000 (Direct Cost: ¥800,000)
Keywords	beam halo / space charge / RFQ / 線形加速器 / サイクロトロン / ビームハーロー / エミッタンス / アルバレ
Research Abstract	1) halo formation n beam transport system One of my graduate students, M.Ikegami studied halo formation from mismatched axisymmetric beams in a periodic channel with Dr. H.Okamoto (Jpn. Appl. Phys., Vol. 36, 7028, 1997). The computer simulation was made by particle-in-cell method with one dimensional approximation. The result shows that a matched beam to the transport system does not cause beam halo but a mismatched beam causes halo by space charge effect. But in this case the halo is created from the peripheral region of the phase space distribution at the starting position. And after the halo is once scraped by a beam collimator it is not created thereafter. This is a hopeful result for a high intensity beam acceleration though it is not realistic three dimensional simulation. 2) Space charge effect in a cyclotron The space charge effect in the cyclotron was estimated to be compared with a linac for an accelerator driven system. The intensity of l0mA at 500MeV may be attainable with third harmonic RF field though the non-linear effect is ambiguous. 3) Multi-rod RFQ linac and accelerator driven system (ADS) A unique structure multi-rod RFQ linac in which beams slalomed was designed. The beam transmission of each channel of the linac is less than 50%, but total beam intensity of the linac can be very much than a usual single channel RFQ linac. An ADS was proposed for the future project of Kyoto University Research Reactor Institute.