AN EXPERIMENTAL AND THEORETICAL STUDY OF THE NON-EQUILIBRIUM PLASMA IN THERMIONIC DISCHARGES.
Abstract
The transition rate equations for the populations of cesium atomic states in a homogeneous, optically thin plasma have been solved for the excited state populations and effective ground-state ionization and recombination coefficients. Free electron densities from 10 to the 12th power to 10 to the 15th power/cu. cm are considered, and a Maxwellian electron velocity distribution at temperatures from 1000 to 3000 K is assumed. These conditions are typical of those in thermionic and magnetohydrodynamic energy converters and other cesium experiments. The rate coefficients used for collision-induced and radiative atomic transitions are described. Molecular processes, diffusion, wall losses, etc. are ignored. The absorption of resonance radiation is simulated by reduction of the spontaneous emission coefficients. Other radiative absorption processes are neglected. The populations are seen to depart significantly from the Boltzmann distribution in steady state, and it is seen that many excited states participate in the ionization and recombination processes. The implications of these results for spectroscopic diagnostics and volume ion production in ignited mode converters are discussed. Progress in the design and construction of an experimental converter which will be used to check the validity of the theoretical model is described. Preliminary observations have confirmed that stable operation can be achieved over the required ranges of temperature and density and that line and continuum intensities are sufficient for detailed spectroscopic analysis of the plasma. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1967
- Accession Number
- AD0807359
Entities
People
- D. W. Norcross
- P. M. Stone
- R. H. Curry
Organizations
- Sperry Corporation