Electrostatic–magnetostatic hybrid probe for measuring the electron distribution function in a magnetized plasma

摘要

A probe has been developed which measures the density (in a magnetized plasma) of electrons with a given parallel energy and also with a given ratio of perpendicular energy to parallel energy. This is done by imposing two noninteracting criteria for electron collection. The electron must first pass an adjustable magnetostatic barrier (a magnetic mirror) which selects electrons according to perpendicular to parallel energy ratio; then the electron must surmount an electrostatic barrier which is well removed behind the mirror, this discriminates on the basis of the electron’s original parallel energy. This probe is straightforward to build and easy to use. A simple formula for obtaining a distribution function map from the data provided by this probe is derived.