Investigations Of Non Equilibrium Plasmas Utilizing Mass And Optical Spectroscopy

This report describes an investigation of the energy exchange processes in nonequilibrium plasmas. The primary objective of the research was to investigate the influence of parameters such as the electron temperature and density, and the presence of walls and electromagnetic fields, on quantities such as the degree of ionization, electrical conductivity, and energy storage in excited atomic states. The research was primarily experimental. The plasmas were generated in solenoidal-coil type RF discharge tubes driven at a frequency of 4 mc. Experiments were carried out over the pressure range of 0.03 Torr to 10 Torr and at specific power levels of about 0.1 to 10 watts/cc using helium as a test gas. Optical spectroscopy was the primary diagnostic tool. Langmuir and magnetic probe, microwave, and calorimetric measurements were also made.

This book deals with the physics of low temperature plasmas of atomic and molecular gases. Several diagnostic methods for nonequilibrium plasma are described. The relevant elementary processes governing the kinetics and transport of atomic and chemically active molecular plasmas are discussed and numerical models of plasmas aimed at systematically solving MHD-equations are also presented. Intended for use by scientists and engineers active in various fields of low-temperature plasma physics, this book is also suitable for teachers and students at pre- and postgraduate level. In chapter 1 general problems of the elementary physics of plasma are considered and the principal ideas relating to plasma properties are given. In chapter 2 the principles which form the basis of atomic and molecular spectra radiated by a plasma are briefly described. Chapter 3 reviews experimental material associated with the peculiarities of molecular excitation processes in nonequilibrium low-temperature plasma. In chapter 4 a number of problems related to the technique and methods of spectroscopy are considered. Chapter 5 presents experimental material gained from studying the peculiarities of molecular excitation spectra from low-pressure gas discharges and describes diagnostics for nonequilibrium chemically active plasma. In chapter 6 the problems of mathematical modeling of equilibrium plasma in arcs, microwave and optical discharges are analyzed. In chapter 7, a theoretical description of nonequilibrium plasma in electrical arcs, microwave and radio-frequency discharges based on two-temperature approximation of the plasma parameters is offered. Chapter 8 presents a detailed case-study on the transport and excitation of a magnetized plasma of intermediate electron density. Several diagnostic techniques and models introduced in earlier chapters are used to obtain information on plasma properties.

This book presents studies of complexity in the context of nonequilibrium phenomena using theory, modeling, simulations, and experiments, both in the laboratory and in nature.

The National Bureau of Standards has embarked on a special program to unify and accelerate its research on hot gases. This work will provide data and theory presently required for the quantitative interpretation of astrophysical and geophysical observations and the measurement of properties of plasmas in the laboratory. The data, measurement techniques, and theoretical methods of analysis draw on activities in the fields on atomic and molecular physics, statistical mechanics and thermodynamics, fluid mechanics, and theoretical astrophysics and geophysics. Both the Washington and Boulder laboratories of the NBS are participating. This note describes the technical objectives of the program and includes in appendices a selected list of papers published at the NBS for the period 1955-1959 and a partial list of Bureau participants.