Table Of ContentLASEII PLASMAS
AND NllCLEAII
ENEIIGY
LASEB PLASMAS
AND NIlCLEAB
ENEBGY
Professor of Physics
University of New South Wales
Kensington-Sidney, Australia
and
Rensselaer Polytechnic Institute
Hartford, Connecticut
Edited by Y uri Ksander
Senior Staff Member
The Rand Corporation
Washington, D.C.
PLENUM PRESS • NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
Hora, Heinrich.
Laser plasmas and nuclear energy.
Includes bibliographical references and index.
1. Plasma (Ionized gases) 2. Laser radiation. 3. Nuclear fusion. 4. Atomic
energy. I. Title.
QC718.H67 530.4'4 74-32287
ISBN-13: 978-1-4684-2087-6 e-ISBN-13: 978-1-4684-2085-2
DOl: 10.1007/978-1-4684-2085-2
The author and publisher gratefully acknowledge permission to reprint material
in the Appendix, granted by the following:
American Institute of Aeronautics and Astronautics, for pp. 369-375 (from AIAA
lournal, 11, 1347-1349, 1973).
The American Institute of Physics, for pp. 123-124 (from Applied Physics Letters,
3, 210--211, 1963); pp. 199-206, 273-282, 283-289 (from The Physics of
Fluids, 7, 981-987, 1964; 12, 182-191,1969; 14, 371-377,1971).
The American Physical Society, for pp. 383-385,409-416,425-431 (from Physical
Review, AI, 821--824, 1970; A6, 2335-2342, 1972; AB, 1582-1588, 1973); pp.
377-381, 417-419, 421-423 (from Physical Review Letters, 30, 89-92, 1973;
30, 1116--1.118, 1973; 31, 1184-1187, 1973).
Chapman and Hall Ltd., for pp. 433-443 (from Opto.Electronics, 5, 491-501,
1973).
Editions Bordas, Dunod, Gauthier.Villars, for pp. 113-117 (from 3rd Interna·
tional Conference on Quantum Electronics, Paris, 1963, Vol. 2, P. Grevet and
N. Bloembergen (eds.), Dunod, Paris, 1964, pp. 1373-1377).
Institute of Electrical and Elecftonic Engineers, Inc., for pp. 119-122 (from IEEE
Journal of Quantum Electronics, QE-4, 864--867, 1968).
International Atomic Energy Agency, for pp. 239-247 (from Nuclear Fusion, 10,
111-116, 1970).
Verlag der Zeitschrift fUr Naturforschung, for pp. 225-238 (from Zeitschrift fUr
Naturforschun8, 25A, 282-295, 1970).
© 1975 Plenum Press, New Y~fk
Softcover reprint of the hardcover 1st edition 1975
A Division of Plenum Publishing Corporation
227 West 17th Street, New York, N.Y. 10011
United Kingdom edition published by Plenum Press, London
A Division of Plenum Publishing Company, Ltd.
4a Lower lohn Street, London WIR 3PD, England
All rights reserved
Nt) part of this book may be reproduced, stored in a retrieval system, or transmitted,
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TO MY WIFE ROSE, nee WEILER
PREFACE
Most of this book was written before October 1973. Thus the
statements concerning the energy crisis are now dated, but remain
valid nevertheless. However, the term "energy crisis" is no longer
the unusual new concept it was when the material was written; it is,
rather, a commonplace expression for a condition with which we are
all only too familiar. The purpose of this book is to point out
that the science and technology of laser-induced nuclear fusion
are an extraordinary subject, which in some way not yet completely
clear can solve the problem of gaining a pollution-free and really
inexhaustible supply of inexpensive energy from the heavy hydrogen
(deuterium) atoms found in all terrestrial waters.
The concept is very obvious and very simple: To heat solid
deuterium or mixtures of deuterium and tritium (superheavy hydrogen)
by laser pulses so rapidly that despite the resulting expansion and
cooling there still take place so many nuclear fusion reactions
tnat the energy produced is greater than the laser energy that had
to be applied. Compression of the plasma by the laser radiation
itself is a more sophisticated refinement of the process, but one
which at the present stage of laser cechnology is needed for the
rapid realization of a laser-fusion reactor for power generation.
This concept of compression can also be applied to the development
of completely safe reactors with controlled microexplosions of
laser-compressed fissionable materials such as uranium and even
boron, which fission completely safely into nonradioactive helium
atoms.
The papers that have been published on this subject are widely
scattered and quite different in content, occasionally providing
contradictory and therefore rather confusing results. To undertake
vii
viii PREFACE
the preparation of an exhaustive monograph would therefore be akin
to the labors of Sisyphus: when finished it would be obsolete.
Many international conferences have been held which are turbulent
mixtures of new and unexpected results with an accumulation of
earlier unexplained results. With an eye to the necessity of re
solving the energy crisis, some attempts have been made to provide
introductory material to this subject. The biannual International
Workshop Conferences on "Laser Interactions and Related Plasma
Phenomena" organized by Helmut J. Schwarz and the author are held
for this purpose. Both reviews and new results are presented and
then -- to the extent that the material is suitable -- published in
proceedings volumes of a fairly representative character. However,
the level is necessarily advanced; and, therefore, both students
and beginners have need of a quick survey and an introduction to
plasma physics of such a nature as to enable them to follow the
papers of these proceedings as well as the current literature. With
this need in mind, this introductory volume was written to provide
in combination with the appended collection of important papers
something akin to a seminar in printed form, to be studied alone
or to be used in conjunction with lectures and discussions.
The author has not been neutral in writing this introduction,
but he has tried to avoid the shortcomings of many so-called "review
articles." Such reviews often tend to be either muddled and undi
gested collections of key words and formulas from a large number
of papers or extended discussions of very specific work by the re
viewer himself to which he has adcied only results by others which
are relevant to his own. However, the author is not free of human
motivation -- otherwise he would not have been able to present the
subject with the enthusiasm and conviction of an active participant
in an exciting field of research -- and, therefore, this work may
also suffer to some extent from the above-mentioned defects. If
that is so and some aspects are emphasized more than they might have
been by another writer, the reader may compensate for it by studying
further in the papers of other authors.
Unavoidably, there is some mixing of highly elementary and in
troductory descriptions of the physical properties of a plasma with
unresolved problems and with some new results. The yet unsolved
questions are especially pointed out, particularly when different
sources lead to confusing and conflicting results. For example,
measurements of the reflectivity of laser-produced plasmas differ by
a factor of 100 or more. There seem to be unexplained characteris
tic phenomena at moderate laser intensities in ruby and neodymium
glass laser pulses around 109 W/cm2, such as the Linlor effect; and
there are discrepancies between the models of homogeneous heating
and of generation of compression waves at 1010 to 1013 W/cm2• At
higher intensities the scattering results are equally complicated.
The inclusion of new results could not be avoided in view of the
presentation of a new method of compression of laser-produced plasma
PREFACE ix
which is much more efficient than the previous approach of gas
dynamic ablation. This method provides a new approach to the entire
field, and the whole discussion is influenced by this new point of
view.
It is a pleasure for the author to thank colleagues and friends
for direct and indirect help in finishing this work, especially
Vice-President Warren C. Stoker and Prof. Helmut Schwarz of Rens
selaer Polytechnic Institute; Dr. Marcel Salvat, Director of Euratom
at IPP Garching, for constant and fruitful cooperation over many
years; and Prof. Moshe J. Lubin of the University of Rochester for
helpful arrangements during the author's term at his laboratory
while on leave from the Max Planck Institut fUr Plasmaphysik
(Association Euratom) in Garching, Germany.
Ottobrunn (Germany) Heinrich Hora
Rotdornweg 4
CONTENTS
1. Introduction 1
1.1 Nuclear Fusion 2
1.2 Laser-Produced Nuclear Fusion 3
2. Lasers 6
2.1 Laser Condition 6
2.2 Operation of Lasers 9
2.3 Available Lasers 12
3. Early Measurements and Gas Breakdown 15
3.1 Gas Breakdown 15
3.2 Plasmas Produced from Solids in Vacuum 18
(Linlor Effect)
4. Microscopic Properties of Plasma 22
4.1 Debye Length 23
4.2 Plasma Frequency 24
4.3 Collisions 26
5. Macroscopic Plasma Physics 29
5.1 Ohm's Law and Electromagnetic Waves 29
5.2 Equation of Motion and Equations of Conservation 31
5.3 Homogeneous Heating 36
6. Refractive Index and Absorption 39
6.1 Linear Properties 40
6.2 Nonlinear Absorption 45
6.3 Relativistic Absorption 47
6.4 Anomalous Absorption and Instabilities 50
7. Dielectric Nonlinear Forces and Dynamic Absorption 52
7.1 Basic Properties of the Dielectric Nonlinear Force 52
7.2 Transferred Momentum and Ion Energies 55
7.3 Predominance of the Nonlinear Force 58
7.4 Self-Focusing of Laser Beams in Plasma 61
xi
xii CONTENTS
7.5 Numerical Examples of Nonlinear Acceleration 64
8. Theory of Laser-Induced Nuclear Fusion 73
8.1 Inertial Confinement 73
8.2 Gas-Dynamic Compression 77
8.3 Direct and More Efficient Transfer of Laser Energy 81
into Mechanical Compression
8.4 New Concepts and Nuclear Fission 84
9. Experiments for Laser-Induced Nuclear Fusion 87
9.1 Irradiation of Spherical Targets 87
9.2 Neutron Generation 88
9.3 Anomalous Experimental Results 90
10. Conclusions 96
11. References 99
12. Appendix. List of Reprinted Papers 110
N. G. Basov and O. N. Krokhin, "The Conditions of
Plasma Heating by the Optical Quantum Generator." 113
N. G. Basov, P. G. Kryukov, S. D. Zakharov, Yu. V.
Senatskiy, and S. V. Chekalin, "Experiments on the
Observation of Neutron Emission at the Focus of High-
power Laser Radiation on a Lithium Deuteride Surface." 119
W. 1. Linlor, "Ion Energies Produced by Laser Giant
Pulse." 123
R. Papoular, "The Initial Stage of the Laser-induced
Gas Breakdown." 125
A. J. Alcock, "Experiments on Self-focusing in Laser-
produced Plasmas." 143
G. Siller, K. BUehl, and H. Hora, "Intense Electron
Emission from Laser-produced Plasmas." 165
H. Hora, "Experimenta 1 Result of Free Ta rgets • " 183
J. M. Dawson, "On the Production of a Plasma by Giant
Laser Pulses." 199
H. Hora, "Some Results of the Self-similarity Model." 207
P. Mulser, "Hydrogen Plasma Production by Giant Pulse
Lasers." 225
H. Hora and H. Wilhelm, "Optical Constants of Fully-
ionized Hydrogen Plasma for Laser Radiation." 239
D. F. DuBois, "Laser-Induced Instabilities and Anoma-
lous Absorption in Dense Plasmas." 249
'H. Hora, "Nonlinear Confining and Deconfining Forces
Associated with the Interaction of Laser Radiation
with a Plasma." 273
J. D. Lindl and P. Kaw, "Ponderomotive Forces on
Laser-produced Plasmas." 283
H. Hora, "Nonlinear Forces in Laser-produced Plasmas." 291
F. F. Chen, "Physical Mechanisms for Laser-Plasma Para-
metric Instabilities." 317
J. H. Nuckolls, "Laser-Induced Implosion and thermo-
nuclear Burn." 341
CONTENTS xiii
L. L. Lengyel, "Exact Steady-state Analogy of Transient
Gas Compression by Coalescing Waves." 369
J. S. Clarke, H. N. Fisher, and R. J. Mason, "Laser-
driven Implosion of Spherical DT Targets to Thermo-
nuclear Burn Conditions." 377
F. F1oux, D. Cognard, L. G. Denoed, G. Piar, D. Parisot,
J. L. Bobin, F. De1obeau, and C. Fauquignon, "Nuclear
Fusion Reactions in Laser-produced Solid Deuterium
Plasmas." 383
N. G. Basov, O. N. Krokhin, and G. V. Sk1izkov, "Heating
of Laser Plasmas for Thermonuclear Fusion." 387
N. G. Basov, Yu. S. Ivanov, O. N. Krokhin, Yu. A.
Mikhay1ov, G. V. Sk1izkov, and S. I. Feodotov,
"Neutron Generation in Spherical Irradiation of a
Target by High-power Laser Radiation." 407
C. Yamanaka, T. Yamanaka, T. Sasaki, K. Yoshida, M.
Waki, and H. B. Kang, "Anomalous Heating of a Plasma
by Lasers." 409
G. F. McCall, F. Young, A. W. Ehler, J. F. Kephardt,
and R. P. Godwin, "Neutron Emission from Laser-
produced Plasmas." 417
M. Goldman, J. Soures, and M. J. Lubin, "Saturation of
Stimulated Back-scattered Radiation in Laser Plasmas." 421
J. W. Shearer, J. Garrison, J. Wong, and J. E. Swain,
"Pair Production by Relativistic Electrons from an
Intense Laser Focus." 425
13. Subject Index 445
