The normal cold-cathode glow discharge.

This paper is a critique of some aspects of the theory of norma cold-cathode glow discharges, with special reference to the development of the discharge in a direction normal to the cathode. It is pointed out that a theory of the normal cathode dark space is available on the basis of Poisson's equation and the Boltzmann transport equation, if conditions at both its cathode and negative glow boundaries are supposed known, whether or not the complexity of the Boltzmann computing is minimized by using as far as possible from the beginning the macroscopic Townsend coefficient <agr>/p and mobility-type relations, or other convenient approximations. Attention is called to the vital part played by the negative glow plasma, and the possibility of improving sharp-boundary cathode dark space theory by applying a Langmuir-Bohm criterion for positive space-charge to form is considered. A more fundamental approach is however to consider the whole discharge from the cathode to the middle of the negative glow or the anode as one unit. The relation between normal discharges and constricted subnormal discharges requires some clarification, in particular to ascertain if the normal discharge retains some subnormal characteristics, and vice versa, and there is urgent need for more data for the plasma parameters (electron and ion number densities and energy distribution functions, and potential contours) for normal negative glows both with and without completely covered cathodes. [ABSTRACT FROM AUTHOR]