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Electron Temperatures and Electron Densities in Microwave Helium Discharges with Pressures Higher than 0.1 MPa
Author(s) -
Sasaki K.,
Soma S.,
Akashi H.,
ElSabbagh M.,
Ikeda Y.
Publication year - 2015
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.201500033
Subject(s) - atomic physics , electron , helium , electron density , electron temperature , materials science , microwave , atmospheric pressure , plasma , physics , nuclear physics , quantum mechanics , meteorology
We adopted laser Thomson scattering for measuring the electron density and the electron temperature of microwave plasmas produced in helium at the pressures higher than the atmospheric pressure. The electron density decreased while we observed the increase in the electron temperature with the pressure. These are reasonable results by considering the decrease in the reduced electric field, the dominant loss of electrons via three‐body recombination with helium as the third body, and the production of electrons with medium energy via heavy particle collisions at the high gas pressure. The temporal variation of the electron temperature had the rise and the fall time constants of approximately 10 ns. The rapid heating and cooling of the electron temperature are due to the fast energy transfer from electrons to helium because of the high collision frequency in the high‐pressure discharge. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)