The column plasma of a dc glow discharge in neon is comprehensively studied by a new self-consistent hybrid method. The method is based on the solution of the steady-state fluid equations of charge carriers and the Poisson equation using electron transport coefficients and ionization frequencies which arise from a space-dependent kinetic treatment of the electron component. The column description comprises, in addition, a space-dependent treatment of the excited particles in the plasma, the treatment of the plasma-wall interaction processes of the charge carriers and the determination of the electric field. The hybrid method provides a very efficient self-consistent column description although it avoids rough approximations often applied in fluid methods. Results of the method for a neon column plasma are compared with those of probe measurements and spectroscopic studies. The results confirm the importance of the ionization of excited neon atoms for the charge carrier production and emphasize the necessity of the detailed description of the excited states included in the column model.

No abstract

No abstract

This paper presents time and space resolved results of spectroscopic measurements in a vacuum circuit breaker experiment during high-current anode modes, i.e., anode spot type 1, anode spot type 2, and anode plume. Excited state densities for Cu I, Cu II, and Cu III transitions are determined during anode spot type 1 and type 2 as well as for the anode plume. Temporal evolution of excited state densities and Cu neutral gas densities are also determined during anode spot type 1 and type 2, which show that the Cu density in front of the anode during anode spot type 2 is about 6 times higher compared to anode spot type 1. Electron densities are also determined during both types of anode spot using Stark broadening. The electron densities during anode spot type 2 are remarkably higher than during anode spot type 1.

The Boltzmann plot method allows to calculate plasma temperatures and pressures if absolutely calibrated emission coefficients of spectral lines are available. However, xenon arcs are not very well suited to be analyzed this way, as there are only a limited number of lines with atomic data available. These lines have high excitation energies in a small interval between 9.8 and 11.5 eV. Uncertainties in the experimental method and in the atomic data further limit the accuracy of the evaluation procedure. This may result in implausible values of temperature and pressure with inadmissible uncertainty. To omit these shortcomings, an iterative scheme is proposed that is making use of additional information about the xenon fill pressure. This method is proved to be robust against noisy data and significantly reduces the uncertainties. Intentionally distorted synthetic data are used to illustrate the performance of the method, and measurements performed on a laboratory xenon high pressure discharge lamp are analyzed resulting in reasonable temperatures and pressures with significantly reduced uncertainties.