CAJ | 학술논문

With the prototype ECR ion source for the next carbon therapy facility in Japan a new series of measurements has been performed in order(a)to find the highest beam currents of C4+ ions,and(b)to study the effect of"special"gas-mixing by using a chemical compound as a feed gas. An isotopic effect has been found in a previous experiment:with deuterated methane(CD4 gas)the C5+ beam currents are about 10% higher than with regular methane(CH4 gas).For butane gases(C4D10 and C4H10 respectively)the isotopic effect for C5+ production is even stronger(>15%).For production of C4+ ions the isotopic effect appears to be absent.It turns out that the relative amount of carbon is much more important:acetylene gives 15%higher C4+ current than butane,which in turn gives about 10% higher C4+ ion currents than methane.