Two-cascade glow discharge ion source†

Abstract

The mechanism of the transformation of a solution into a low-temperature plasma is considered. The analyzed solution enters a hollow cathode directly from the atmosphere through a capillary. As it enters the hollow cathode the solution acquires a linear speed greater than 1-2 mm s ^–1 in a narrow gap between a ball or wire and the capillary walls. After evaporation of the solvent, the impurity remains on the walls of the hollow cathode. On the basis of these considerations, a two-cascade glow discharge ion source for solution analysis was developed. The first cascade of the source consists of a capillary, with a wire or ball inserted into it, and a cylindrical anode. The anode of the first cascade is, in turn, the hollow cathode of the second cascade. The discharge current of the first cascade is 1-3 mA at a voltage of 1-3 kV, and that of the second cascade is 10-30 mA at a voltage up to 4 kV. The sensitivity of the proposed source is comparable to that of an ICP source.