Ion flux transmission in a magnetically filtered vacuum arc

H. KELLY; A. MÁRQUEZ; M. PIRRERA

BRAZILIAN JOURNAL OF PHYSICS

Brasilian Physical Society

Año: 2004 vol. 34 p. 1513 - 1517

0103-9733

Measurements on the ion flux transmission in a magnetically filtered d-c vacuum arc are presented. The device includes a metallic plasma-generating chamber with water-cooled electrodes coupled to a substrate chamber through a quarter-torus magnetic filter. It is employed a Copper cathode (6 cm in diameter) with a Copper annular anode. The filter consists in a steel cylinder 500 mm length and 100 mm inner diameter with 90o of bending angle and corrugated lateral walls, surrounded by a magnetic field generating coil. The arc is operated at a current level of 100 A, and the intensity of the filtering magnetic field was in the range 0 – 200 G (measured at the knee of the filter). This magnetic field is enough high so as to magnetize the electrons but not the ions. The discharge is ignited by bringing (and later removing) a tungsten striker into contact with the cathode. The arc voltage drop, the floating potentials of the filter and the plasma, and the ion current collected by probes located at different positions as functions of the magnetic field intensity are reported and compared with measurements presented in the literature with other similar devices.