Construction and characterization of an Ar-Fe hollow cathode tube with modeling of the argon plasma discharge

Summary form only given. An argon-iron hollow cathode tube (HCT) was developed to be used in laser atomic spectroscopy experiments. This HCT has been employed in laser absorption and optogalvanic signal measurements. The light absorption and optogalvanic signal detection were accomplished using a tunable dye laser resonant with Ar 3p/sup 5/4p(/sup 3/S/sub 1/)→3p/sup 5/4d(3D/sub 1//sup 0/) transition, corresponding to wave length 591.2 nm. The cathode of HCT consists of an iron cylinder with 24 mm length and 8.0 mm radius with a 2.8 mm diameter hole. The cathode body was supported by two circular alumina disks and centrally attached by them. In one of the disks a number of holes were drilled in order to allow the insertion of the cathode feed wires. A thermalcouple was placed in contact with the cathode surface to measure the cathode temperature. The tube was made of glass type Schott 8250 with dimensions of 40 mm in diameter and 18 cm in length. The optical windows were made of fused-quartz and arranged in Brewster angle. The tube was sealed with 5 Torr argon pressure. A modeling of argon discharge based on a two-fluid theory of electron and argon ion transport was also developed in order to describe the electron-ion number densities, particle fluxes and electric potential profiles.