Premium
Probe Measurements in Electronegative Plasmas: Modeling the Perturbative Effects of the Probe‐Holder
Author(s) -
Kudryavtsev A. A.,
Demidov V. I.,
DeJoseph C. A.,
Adams S. F.,
Serditov K. Yu.
Publication year - 2009
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.200910034
Subject(s) - ambipolar diffusion , ion , plasma , electric field , atomic physics , electron , electron density , argon , electron temperature , plasma parameters , plasma diagnostics , materials science , physics , quantum mechanics
A basic property of an electronegative plasma is its separation into two distinct regions: an ion‐ion region far from boundaries, where the densities of positive and negative ions are higher then electron density, and a near‐boundary electron‐ion region, where negative ions have practically negligible density. This is due to the influence of the ambipolar electric field, which depends on electron (not negative ion) plasma parameters. This electric field “holds off” negative ions from the boundary, as the ions have lower mobility and temperature compared to the electrons. Therefore, negative ions will be repelled by any object inserted into the plasma. This can lead to errors in measurements of negative ion and electron parameters by any invasive method. Numerical modeling of electric probes in an argon‐oxygen plasma clearly demonstrates possible errors of direct measurements of negative ion probe current. This can also affect results from the photo‐detachment method and direct measurements of negative ion energy distribution (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)