Increasing B+ current from a microwave ion source by simultaneously utilizing new techniques

In previous papers we reported two separate methods for enhancing B⁺ ion current. One was to optimize the discharge-chamber volume by comparing it with the computer-simulated magnetic field. Resultantly the modified chamber that has larger volume than the standard chamber provided B⁺ ion current over 13 mA. The other was to enhance the secondary electron emissivity of the chamber wall by adding MgO into the chamber material. The experiment on the standard chamber showed the 5% addition of MgO resulted in 60% increase of the B⁺ ion current. In this study we have utilized these two methods simultaneously, that is, we have tested the modified chamber that is made of boron nitride with MgO mixed. As a result we have obtained B⁺ ion current of 15 mA on an old beam line having moderate transmission.