Anode fall as relevant to plasma thrusters
Contributors: Naval Postgraduate School (U.S.) 
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1997
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 109
Subjects: ION DENSITY; PLASMAS (PHYSICS); ANODES
Description: The behavior of the electric field together with the electron and ion densities in the vicinity of a non-emitting, plane      anode is investigated. The selected approach involves non-linear analysis techniques on the continuum equations      for steady-state, isothermal conditions where both ionization and two- body recombination are included. Ions,      created through electron bombardment of neutral atoms, are repelled toward two stagnation regions: within or      near the sheath boundary and near the plasma interface. These equilibria form as a result of the chemistry present:      recombination establishes the latter while ionization stipulates the former. As presented, the sheath is      fundamentally unstable - ions are driven toward the negative electrode. Using nitrogen data for a numeric      example, the following observations are made: a sufficiently strong applied electric field pushes the ion density      toward that of the electrons through a well - a constrictive phenomenon. Both a transition region, dominated by      density gradients, and a diffusion-driven zone are found to move the system toward the plasma interface. The      characteristics of this process are influenced by the applied electric field, but the instability of the      chemistry-induced stagnation regions precludes numeric convergence. Insufficient dissipation may prevent the      stability of the anode fall model as presented. Suggested improvements to the model descriptions include      considering the effects of temperature gradients, magnetic fields, three-body recombination, diffusion written in      terms of the electric field, multi-dimensionality and/or time-dependencies.
Notes: Thesis advisors, Oscar Biblarz, Christopher L. Frenzen.

Thesis (Degree of Aeronautical & Astronautical Engineer and M.S. in Astronautical Engineering) Naval Postgraduate School, June 1997.

Includes bibliographical references (p. 103-107)

Also available online.

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dk/dk cc:9116 02/04/98.