Waves in Plasma Sheaths and at Boundaries: Theory and Computer Experiments
Abstract
High frequency waves which propagate at the edges of plasmas bounded by metal (conducting) boundaries are treated in great detail, in theory, and with many-particle simulations. There is no applied magnetic field; the plasma and waves are unmagnetized. First, a linear theory and simulation are made, to include the sheath and the pre-sheath from first principles and self-consistently. The detailed structure of these waves, excited at small amplitudes (from noise in most cases), is obtained, specifically, the dispersion and eigenfields. These results are compared and contrasted with the well-known Tonks-Dattner (transverse, or dipole) resonances and Gould-Trivelpiece waves (longitudinal). The former are the cutoff frequencies for the latter waves. Second, some of these plasma surface waves are driven by sufficient excitation to obtain a discharge (usually meaning sufficient plasma heating to obtain ionization by electrons). In a one-dimensional bounded planar slab model, the drive is near the series resonance frequency, allowing very low voltage drive (a few volts). (Such plasmas have been made in laboratories, for some time now.) Similarly, in two- dimensional models (both electrostatic periodic-bounded and electromagnetic fully bounded - a cavity), the waves are driven by low antenna voltages, at plasma resonance (not vacuum cavity resonance). Considerable information is provided as to the (new) wave heating mechanisms, reasons for seeking the resonance, drive frequency-density scaling, and more. There are numerous practical applications of these plasma surface driven waves, especially the resonantly driven ones. This thesis provides much more structure and details as to these high frequency waves than has been given heretofore.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 31, 1997
- Accession Number
- ADA332802
Entities
People
- Charles K. Birdsall
- David J. Cooperberg
Organizations
- University of California, Berkeley