The effect of Neodymium-in-glass laser radiation on the populations of excited atoms in a partially ionized gas is described. The radiation fluxes that exist in such plasmas are normally so small that the process of photoionization is negligible compared with other processes. However the application of external radiation via a laser source can severely perturb the populations of excited atoms. At 'moderate' photon fluxes (< 1026 photons/cm2) single photon ionization is important and is capable of perturbing the populations of excited states. The dependence of these reductions on laser power and plasma conditions has been determined for energy levels in Hydrogen. Photoionization effects due to laser radiation could not be seen in partially ionized Argon and Xenon gas discharges. This has led to an evaluation of the rate of production of excited Argon atoms. The effect of the laser beam profile on the observed reduction in the populations of excited Hydrogen atoms has been demonstrated. The radiation source used in the experiments which are described, is a Neodymium-in-glass laser emitting radiation at 1.06 Um. It produced unfocussed beam powers of about 20 MW. The results which were obtained are adequately described by a rate equation model of the plasma which has allowed a simple analysis of experimental data.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:637468 |
| Date | January 1980 |
| Creators | Jones, J. I. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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