A review is given of theoretical and experimental investigations on rotating plasmas. The basic equations are discussed from the microscopic and macroscopic points of view, including the balance of matter, momentum, and heat, as well as associated stability problems and limiting effects. Various types of devices are described, and obtained experimental results are compared with theoretical predictions. The review also summarizes the applications of rotating plasmas to fusion research, cosmical physics, and special technical arrangements such as plasma centrifuges, adjustable plasma condensers, and plasma gun and propulsion systems.
EXTENDED ELECTROMAGNETIC THEORY: SPACE CHARGE IN VACUO AND THE REST MASS OF THE PHOTONCopyright © 1998 by World Scientific Publishing Co. Pte. Ltd.All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic t mechanical, including photocopying, recording or any information storage and retrieval system now known or be invented, without written permission from the Publisher. PREFACEConventional electromagnetic theory, based on Maxwell's equations, has been successful in treating manifold problems in physics during the past one hundred over years. However, there are questions that have not been given fully adequate answers using the conventional theory, and this therefore suggests that revisions have become necessary. In addition, such revisions can also offer extended possibilities for the theory by opening new fields of application.One example of a not fully-answered question is that of the total reflection of electromagnetic waves propagating in a dissipative medium bounded by vacuum interface. Another example is that of electrodynamic models of the photon which has to behave both as a particle (boson) and a wave, and where the particle model should satisfy physically relevant boundary conditions, both at its centre and at infinity. A third example is that of electrodynamic models of leptons, in particular of the electron. The latter behaves like a "point charge" or a particle of extremely small radius, the model thereby having to satisfy relevant boundary conditions at the centre and at infinity.More recently, a number of attempts have been made to modify Maxwell's equations, with the purpose of dealing with unsolved problems and of extending the range of applicability. A description of all the proposed revisions is out of the scope of this book, which summarizes the investigations made by the authors and some associated works.The extended electromagnetic theory described here has been elaborated on along two lines. The first is based on the hypothesis of nonzero electric field divergence in vacuo. It leads to steady electromagnetic equilibria, such as axisymmetric electrically charged or neutral states, with possible applications to leptons and string models, as well as to new types of plane and axisymmetric electromagnetic space-charge waves, with possible applications to the photon with a nonzero rest mass. The second line is based on the hypothesis of a nonzero electric conductivity in vacuo. It leads to modified electromagnetic waves with a group velocity being slightly less than the conventional velocity CONTENTS
In several experiments on a magnetically confined plasma and under certain conditions of a fusion reactor in stationary operation, neutral gas will be present in the regions surrounding the plasma. The inflow of neutrals and the outflow of plasma by diffusion or free streaming is studied in this paper, both for closed and open-ended systems: In a closed bottle neutral gas will not be able to penetrate through the cool boundary layers into the hot core of a high-density plasma. At plasma densities above 1021 m−3 the energy losses from interaction with the neutrals become negligible compared to the thermonuclear power production, but not at densities below 1019 m−3. This is due to the fact that the penetration depth of the neutrals depends on the ionization rate and becomes about 10−3 and 0.1 m at the densities 1021 and 1019 m−3. Further, the neutral gas inflow will be delayed by diffusion through a cool boundary region of sufficiently high density. In stationary operation the plasma density will be determined by the magnetic field strength and the density of the surrounding neutral gas. A condition for stable heat balance in a boundary region of finite thickness is deduced in this paper. As an alternative to a fusion device where the plasma is surrounded by an ultra-high vacuum region, it is therefore possible to surround a high-density plasma by a neutral gas blanket. The latter should be dense enough for released wall impurities to diffuse only slowly towards the plasma boundary. With a superimposed stream of neutral gas along the plasma boundary, the impurities can then be removed before reaching the plasma. In an open-ended system, thin layers of neutral gas are formed by plasma particles which escape along the magnetic field and recombine at the end walls. The theory agrees with measurements of the density of a fully ionized plasma as a function of the applied magnetic field and the density of the surrounding neutral gas. It also suggests that Bohm diffusion has not been present in earlier experiments with rotating plasmas where the density was found to decay at a very slow rate during free-wheeling.
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