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Title: Plasmas generated by ultra-violet light rather than electron impact

We analyze, in both plane and cylindrical geometries, a collisionless plasma consisting of an inner region where generation occurs by UV illumination, and an un-illuminated outer region with no generation. Ions generated in the inner region flow outwards through the outer region and into a wall. We solve for this system's steady state, first in the quasi-neutral regime (where the Debye length λ{sub D} vanishes and analytic solutions exist) and then in the general case, which we solve numerically. In the general case, a double layer forms where the illuminated and un-illuminated regions meet, and an approximately quasi-neutral plasma connects the double layer to the wall sheath; in plane geometry, the ions coast through the quasi-neutral section at slightly more than the Bohm speed c{sub s}. The system, although simple, therefore has two novel features: a double layer that does not require counter-streaming ions and electrons, and a quasi-neutral plasma where ions travel in straight lines with at least the Bohm speed. We close with a précis of our asymptotic solutions of this system, and suggest how our theoretical conclusions might be extended and tested in the laboratory.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Astronomy and Physics, The Open University, Milton Keynes MK7 6AA (United Kingdom)
  2. University College, University of Oxford, Oxford OX1 4BH, United Kingdom and OCIAM, Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom)
  3. (United Kingdom)
  4. Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)
  5. Departamento de Fisica, CCCEE, Universidade de Madeira, Largo do Municipio, 9000 Funchal (Portugal)
Publication Date:
OSTI Identifier:
22218385
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 12; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ANALYTICAL SOLUTION; APPROXIMATIONS; ASYMPTOTIC SOLUTIONS; BOHM CRITERION; COLLISIONLESS PLASMA; CYLINDRICAL CONFIGURATION; DEBYE LENGTH; ELECTRONS; MULTICHARGED IONS; PHOTOIONIZATION; PLASMA PRODUCTION; PLASMA SHEATH; STEADY-STATE CONDITIONS; VISIBLE RADIATION