Electromagnetic Characteristics of a Superconducting Magnet for 28GHz ECR Ion Source according to the Series Resistance of a Protection Circuit

摘要

A linear accelerator, called RAON, has been being developed as a part of RareIsotope Science Project (RISP) by Institute for Basic Science (IBS) [1]. Thelinear accelerator utilizes an electron cyclotron resonance (ECR) ion sourcefor providing intense highly charged ion beams to the linear accelerator. 28GHzECR ion source can extract heavy ion beams from proton to uranium. Asuperconducting magnet system for 28GHz ECR ion source is composed of hexapolecoils and four solenoid coils made with low Tc superconducting wires of NbTi[2]. The electromagnetic force acts on the superconducting magnets due to themagnetic field and flowing current in case of not only normal state but alsoquench state [3]. In case of quench on hexapole coils, unbalanced flowingcurrent among the hexapole coils is generated and it causes unbalancedelectromagnetic force. Coil motions and coil strains in quench state are largerthan those in normal state due to unbalanced electromagnetic force amonghexapole coils. Therefore, analysis on electromagnetic characteristics ofsuperconducting magnet for 28GHz ECR ion source according to the seriesresistance of protection circuit in case of quench should be conducted. In thispaper, analysis on electromagnetic characteristics of superconducting hexapolecoils for 28GHz ECR ion source according to the series resistance of protectioncircuit in case of quench is performed by using finite elements method (FEM)simulation.