Effect of Ion Escape Velocity and Conversion Surface Material on H- Production

According to generally accepted models surface production of negative ions depends on ion escape velocity and work function of the surface. We have conducted an experimental study addressing the role of the ion escape velocity on H− production. A converter‐type ion source at Los Alamos Neutron Science Center was employed for the experiment. The ion escape velocity was affected by varying the bias voltage of the converter electrode. It was observed that due to enhanced stripping of H− no direct gain of extracted beam current can be achieved by increasing the converter voltage. The conversion efficiency of H− was observed to vary with converter voltage and follow the existing theories in qual…