Balmer-alpha emission and hydrogen-atom energy in ion-source discharges
- 1 April 1982
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review A
- Vol. 25 (4), 2152-2163
- https://doi.org/10.1103/physreva.25.2152
Abstract
The structure of the hydrogen Balmer-alpha line emission profiles from three types of neutral-beam-injector ion-source plasmas [filling pressure ∼10 mTorr, electron density ∼(1-2)× , electron temperature ∼2-4 eV] is studied with the aid of a simple model for the neutral-particle balance and emission. This model includes molecular and atomic reactions, wall interactions, and nonthermal electrons. A large fraction of the is produced by dissociative excitation of and dissociative recombination of , while the remainder is produced by excitation of H atoms, most of which have energies that are close to the characteristic dissociation energies. The linewidth is thus insensitive to the discharge operating conditions and equals ∼0.27 Å when only slow (∼0.3 eV) dissociatively excited atoms are present or ∼0.35 Å when fast (> 1 eV) atoms, apparently also produced in dissociation reactions, are present as well.
Keywords
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