Measurement of electron energetics in the equatorial and polar planes of a compact dipole plasma driven at steady state

Abstract

The electron energy distribution function (EEDF) is investigated in a plasma driven at steady state and confined by a single permanent dipole magnet, employing electron cyclotron resonance (ECR) heating using microwaves of 2.45 GHz. Directional retarding field energy analyzers (RFEA) are used to explore the EEDF in the equatorial and polar planes of the dipole magnetic field. The plasma confined in the magnetic field is found to be Maxwellian in most of the available space. Electrons have higher values of average energy in the direction parallel to the magnetic field for both the equatorial and polar planes. The energetic electron rich regions are found at specific locations (r = 9 cm in the equatorial plane, and r = 5 cm and near the boundary region around r = 17 cm in the polar plane). The process rates such as electron neutral collisions and ionization show anisotropic variation in the polar plane of the dipole plasma.