A Two-Electron-Group Model for a High Current Pseudospark or Back-Lighted Thyratron Plasma

Abstract

A two-electron-group model is applied to a hydrogen pseudospark and/or backlighted thyratron switch plasma with peak electron density of 1–5x1015 cm-3 and peak current density of 104 A/cm2. In addition to a Maxwellian “bulk” plasma a second group of monoenergetic non-thermal electrons (energy ≥ 100 eV) is assumed to be produced in the high electric field region of the cathode fall. Collisional and radiative processes between electrons, ions and atomic hydrogen are modeled by a set of rate equations and line intensity ratios are compared with measurements. Under these high current conditions, for an initial density nH2≈1016 cm-3 the evaluated “bulk” plasma parameters are electron density of 1–3x1015 cm-3 and electron temperature of 1–1.5 eV, the estimated “beam” density is ≈ 1012–1013 cm-3. Results obtained from a Fokker-Planck and a transport momentum equation suggest the possibility of producing in a simple way a very high density electron beam.