Electron Beam as a Method of Finding the Potential Distribution in a Cylindrically Symmetric Plasma

摘要

An electron beam has been used to determine the plasma potential and charge density as a function of radius for an inertially confined tenuous plasma. The column of plasma was formed by a collimator in front of a plasma gun. The observations showed a positive charge density inside the region of approximately uniform ion density but with the net charge density having a peak well inside the plasma column. A significant negative charge density was observed outside the column of ions. An inversion of the integral equation relating the deflection of the electron beam to the internal electric field has been performed. This inversion gave the plasma potential as a function of radius. The deflection of the electron beam at a constant impact parameter oscillated as a function of distance from the collimator for the plasma cylinder. This oscillation was evident only in certain regions and the wavelength was not a constant.