Plasmas generated by ultra-violet light rather than electron impact
File(s)
Accepted version
Author(s)
Franklin, RN
Allen, JE
Thomas, DM
Benilov, MS
Type
Journal Article
Abstract
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 ${\lambda}_D$ 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 $c_s$. 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 pr\'{e}cis of our
asymptotic solutions of this system, and suggest how our theoretical
conclusions might be extended and tested in the laboratory.
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 ${\lambda}_D$ 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 $c_s$. 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 pr\'{e}cis of our
asymptotic solutions of this system, and suggest how our theoretical
conclusions might be extended and tested in the laboratory.
Date Issued
2013-12-11
Date Acceptance
2013-11-01
Citation
Physics of Plasmas, 2013, 20 (12)
ISSN
1070-664X
Publisher
American Institute of Physics
Journal / Book Title
Physics of Plasmas
Volume
20
Issue
12
Copyright Statement
© 2013 AIP Publishing LLC. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in https://doi.org/10.1063/1.4848715
Identifier
http://scitation.aip.org/content/aip/journal/pop/20/12/10.1063/1.4848715
Subjects
Science & Technology
Physical Sciences
Physics, Fluids & Plasmas
Physics
SHEATH
physics.plasm-ph
physics.plasm-ph
Fluids & Plasmas
0201 Astronomical and Space Sciences
0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
0203 Classical Physics
Notes
3 figures
Publication Status
Published
Article Number
123508
Date Publish Online
2013-12-11