Three designs for negative‐ion plasma sources are described. Two sources utilize metal hexafluorides such as SF6and WF6to scavenge electrons from electron‐ion plasmas and the third relies upon surface ionization of alkali halide salts on heated alumina and zirconia. SF6introduced into electron‐ion plasmas yielded negative‐ion plasma densities of 1010cm−3with low residual electron densities, (ne/ni∼0.01–0.05). On alumina, plasma densities of 5×109cm−3were obtained for CsCl, CsI, and KI and 109cm−3for KCl. On zirconia 1010cm−3densities were obtained for CsCl. For alkali halide sources, electron densities ofne/ni≲10−4have been achieved.