Density dependence on negative corona onset voltage in helium

摘要

This paper presents the results of experiments in gaseous helium, in point cathode-plane geometry, for a wide range of densities (3.l0{sup}(l9)-2.l0{sup}(2l) cm{sup}-3). A current instability occurs at a threshold voltage V{sub}s. ForV>V{sub}s, a space charge limited current is observed. The nature of charge carriers deduced from their mobility value and the variation of V{sub}s with density is discussed as a function of helium purity.