Ion extraction from a plasma
Date
1980
Authors
Aston, Graeme, author
Kaufman, Harold R., advisor
Wilbur, Paul J., advisor
Fairbank, William M., Jr., committee member
Sites, James R., committee member
Journal Title
Journal ISSN
Volume Title
Abstract
An experimental investigation of the physical processes governing ion extraction from a plasma is presented. The screen hole plasma sheath of a multi-aperture ion accelerator system is defined by equipotential plots for a variety of accelerator system geometries and operating conditions. A sheath thickness of at least fifteen Debye lengths is shown to be typical. The electron density variation within the sheath satisfies a Maxwell-Boltzmann density distribution at an effective electron temperature dependent on the discharge plasma primary-to-Maxwellian electron density ratio. Plasma ion flow up to and through the sheath is predominately one dimensional and the ions enter the sheath with a modified Bohm velocity. Low values of the screen grid thickness to screen hole diameter ratio give good ion focusing and high extracted ion currents because of the effect of screen webbing on ion focusing.
Description
Rights Access
Subject
Plasma (Ionized gases)
Ions