Physics of Electric Propulsion

Abstract

REVIEWED BY STEWART WAY 1 THE author, who through his own pioneering contributions is eminently qualified, has brought out a most useful and welcome book on MHD power generation. The book is clearly written and will be useful to graduate students, practicing engineers, and MHD specialists. Greatest value will accrue by reading the book from .start to finish, but it will also be very valuable as a reference work. Chapter 1 introduces one to the elementary ideas of the MHD generator in simplest terms, with appropriate reference to the role and significance of the magnetic Reynolds number. Equilibrium ionization and conductivity are discussed in the second chapter, with consideration of the generalized ohm's law, Hall effects, and ion slip. Chapters 3 and 4 go into a thorough discussion of flow phenomena in the MHD generator, engineering consequences of the Hall effects, electrode segmentation, load circuits, finite electrode effects, and influence of nonuniformities in conductivity. An entire chapter is devoted to the most important subject of nonequilibrium ionization, the conditions for its realization, and the problems and difficulties it may lead to. Another chapter deals entirely with magnets, their optimization and coil design considerations, with discussion also of superconducting magnets. The last two chapters take up design and engineering considerations including brief but good treatments of sidewalls and electrodes. Power plant arrangements using MHD generators are also treated, including central station systems, rocket-driven generators for short bursts, and nuclear-heated plants for commercial and space power applications. Additional useful reference information on conductivity properties, physical constants, etc., is given in appendices. Though this book tends to be oriented more toward generators using seeded noble gases than combustion products, it is a quite general and lucid treatment of generator fundamentals and problems, and will therefore be highly useful to investigators of all types of MHD power systems.

MPD Thruster Performance Analytic Models

“…One outstanding issue in modeling thrust was the value of a to be used in the thrust coefficient definition. Common values range from 0.25 to 0.75 (Jahn, 1968). In the course of this study, values of 0.0 to 0.75 were considered; a value of a=0.75 was found to give the best agreement with data.…”

“…where r a is the thruster anode radius, r c is the central cathode radius, and a is a term accounting for thrust contributions from the cathode tip (Jahn, 1968). This model was initially used by researchers to describe MPDT thrust over the full range of currents and mass flow rates; however, subsequent thrust measurements showed that the thrust departed from this model at low values of current and exhaust velocity (Gilland, 1987).…”

“…There are several MPDT thrust models in the literature; of these, the most recent self-field models were examined for this system model: 1.) the modified Mäcker model, (Jahn, 1968, Choueiri, 1987 2.) the Tikhonov model (Tikhonov, 1993), and 3.)…”

Dimensionless performance model for gas-fed pulsed plasma thrusters

“…[1,2,3,4], as well as nondimensional schemes, refs. [5,6]. In most of these models and the model described in this paper, an inductor, capacitor, and resistor are placed in series to represent the moving discharge as an LCR circuit.…”

Modeling of inelastic collisions in a multifluid plasma: Excitation and deexcitation

“…Modeling of nonequilibrium processes in a low-temperature partially ionized plasma is of particular interest to a wide range of technical fields such as gas discharge, electric propulsion, spectroscopic and laser diagnostics, and material science [1][2][3] . The complexity of the model is largely due to the characterization of various collisional and radiative processes, occurring at a wide range of spatial and temporal scales 4,5 .…”