Extraction of H− beams from a magnetically filtered multicusp source

H− ions produced by volume processes have been extracted from a multicusp source operated with a magnetic filter and accelerated to form a high-quality beam. It was found that the H− beam current increased almost linearly with the discharge current. An H− ion current density of 38 mA/cm2 was obtained with a discharge current of approximately 350 A. The accelerated beam was mass analyzed and the emittance of the H− component was measured. The electron component and the percentage of ion impurity in the extracted beam were also determined.