Academy of Science of the USSR
Institute of Applied Physics

STRONG MICROWAVES IN PLASMAS
Volume 1

PROCEEDINGS OF THE INTERNATIONAL WORKSHOP
Suzdal, 18 - 23 September 1990
Edited by A.G. Litvak

Editor's Preface
Recent advance in the development of powerful sources of microwave radiation introduced into plasma experiments new microwave devices, such as gyrotron and generators of the BWO-, CARM- and FEL-type operating at high-current beams. It also contributed to extensive investigation of powerful microwave interaction with plasma, rich in new physical effects. For example, one of the first experiments on the interaction of powerful electromagnetic waves with extended plasma was performed in, 1970 in Gorky (now Nizhny Novgorod), hardly had the first gyrotron been invented and produced. This experiment, in which the effect of wave beam self-focusing in plasma was first observed, manifested, at the same time, true potentialities of the gyrotron as a powerful source of millimeter wavelength radiation. It also initiated proposals on using gyrotrons for ECR heating of toroidal plasma at the loffe Institute in Leningrad and Kurchatov Institute in Moscow. A few years later the concept of plasma ECR heating with quasi-optical beams of electromagnetic waves in large-scale tokamaks was developed. Similar ideas are widely used also for lower-hybrid heating and current drive. For these purposes gyrotrons operating at centimeter wavelengths are also produced. Thus, ECRH and LH heating are not only close conceptually, but use similar equipment.
LH heating experiments are principally connected with nonlinear effects, while for ECRH it is usually possible to eliminate them. The situation is essentially different when short-pulse FELs are used for ECR heating. In the planned experiments within the MTX project (Livermore), where nanosecond pulses with gygawatt powers are employed, even relativistic dependence of the electron mass on its vibrational energy gains significance, and changes the character of ECR absorption drastically.
Development of powerful microwave sources gave rise also to extended study of the so-called freely-localized gas discharge in focused wave beams. It is of great interest as a new peculiar object of nonlinear physics; certainly, it has a lot of various applications as well. In the recent ten years these investigations have formed an independent and rather broad field of plasma physics.
Thus, now there are several lines of research within plasma physics, which are closely interrelated and highly dependent on the present situation with powerful microwave sources. It was only natural to organize a special meeting for researchers in these fields. The Institute of Applied Physics in Nizhny Novgorod is involved in studying all the said problems, so we pioneered this international endeavour.
The present book is a collection of review papers and some interesting contributions of the International Workshop on Strong Miciowaves in Plasma held in Suzdal on September 19-23, 1990. In the participants' opinion, it proved to be exceedingly fruitful. We hope that the published materials giving the state-of-art overview of research in this field, will be useful also for a Reader interested in the problems of developing powerful sources of coherent microwaves and interaction of powerful electromagnetic radiation with plasma.
A.G. Litvak

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