小型ECRイオン源Kei2における炭素の多価イオン生成試験

A compact ECR ion source for high-energy carbon-ion therapy facility has been developed at NIRS (National Institute of Radiological Sciences). The prototype compact ECR ion source Kei2 was designed for production of C4+ ions; its performance is by far better than necessary for the requirements for the carbon facility. The maximum current was more than 1 emA under the extraction voltage of 40 kV. In order to obtain highly charged carbon ion (5+, 6+) with high intensity for reduce the size of injector LINAC for next carbon therapy facility, we investigate optimization of compound carbon gases and increase microwave power. Usually, carbon molecular gases (e.g. CH4 gas) are applied for production of the carbon ions. In previous experiments, the CH4, C4H10 and C2H2 gases were already tested at Kei2-source. In these measurements it was found that in C2H2 the ratio of carbon to hydrogen is the best for production of carbon ion.第6回日本加速器学会200