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Ion collection from a plasma by a pinholeIon focusing by a biased pinhole is studied numerically. Laplace's equation is solved in 3-D for cylindrical symmetry on a constant grid to determine the potential field produced by a biased pinhole in a dielectric material. Focusing factors are studied for ions of uniform incident velocity with a 3-D Maxwellian distribution superimposed. Ion currents to the pinhole are found by particle tracking. The focusing factor of positive ions as a function of initial velocity, temperature, injection radius, and hole size is reported. For a typical Space Station Freedom environment (oxygen ions having a 4.5 eV ram energy, 0.1 eV temperature, and a -140 V biased pinhole), a focusing factor of 13.35 is found for a 1.5 mm radius pinhole.
Document ID
19920013125
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Snyder, David B. (NASA Lewis Research Center Cleveland, OH, United States)
Herr, Joel L. (Sverdrup Technology, Inc., Cleveland OH., United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1992
Publication Information
Publication: NASA. Johnson Space Center, 5th Annual Workshop on Space Operations Applications and Research (SOAR 1991), Volume 2
Subject Category
Plasma Physics
Accession Number
92N22368
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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