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PHYSICS THROUGH THE 1990s Plasmas and Fluids Pane} on the Physics of Plasmas and Fluids Physics Survey Committee Board on Physics and Astronomy Commission on Physical Sciences, Mathematics, and Resources National Research Council NATIONAL ACADEMY PRESS Washington, D.C. 1986
NATIONAL ACADEMY PRESS 2101 Constitution Avenue, NW Washington, DC 20418 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors, according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Research Council was established by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and of advising the federal government. The Council operates in accordance with general policies determined by the Academy under the authority of its congressional charter of 1863, which establishes the Academy as a private, nonprofit, self-governing membership corporation. The Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in the conduct of their services to the government, the public, and the scientific and engineering communities. It is administered jointly by both Academies and the Institute of Medicine. The National Academy of Engineering and the Institute of Medicine were established in 1964 and 1970, respectively, under the charter of the National Academy of Sciences. The Board on Physics and Astronomy is pleased to acknowledge generous support for the Physics Survey from the Department of Energy, the National Science Foundation, the Department of Defense, the National Aeronautics and Space Administration, the Department of Commerce, the American Physical Society, Coherent (Laser Products Division), General Electric Company, General Motors Foundation, and International Business Machines Corporation. Library of Congress Cataloging in Publication Data Main entry under title: Plasmas and fluids. (Physics through the 1990s) Bibliography: p. Includes index. 1. Plasma (Ionized gases) 2. Space plasmas. 3. Fluids. I. National Research Council (U.S.). Panel on the Physics of Plasmas and Fluids. II. Series. QC718.P54 1985 530.4'4 85-10634 ISBN 0-309-03548-1 Printed in the United States of America First Printing, April 19 86 Second Printing, September 1986 Third Printing, January 1987
PANEL ON THE PHYSICS OF PLASMAS AND FLUIDS RoNA~D C. Davidson, Massachusetts Institute of Technology, Co-chairman JOHN M. DAWSON, University of California, Los Angeles, Co-chairman GEORGE BEKEF1, Massachusetts Institute of Technology RoY Gould, California Institute of Technology ABRAHAM HERTZBERG, University of Washington CHARLES F. KENNEL, University of California, Los Angeles Louts J. LANzERoTT~, AT&T Bell Laboratories E. P. MUNTZ, University of Southern California R~cHARD F. POST, Lawrence Livermore National Laboratory NORMAN ROSTOKER, University of California, Irvine PAUL H. RUTHERFORD, Princeton University Plasma Physics Laboratory Subpanel on Fluid Physics A. HERTZBERG, University of Washington, Chairman A. AcR~vos, Stanford University D. HENDERSON, Los Alamo s National Laboratory J. L. KERREBROCK, Massachusetts Institute of Technology J. L. LACKEY, Cornell University R. W. MACCORMACK, University of Washington F. E. MARBLE, California Institute of Technology E. P. MUNTZ, University of Southern California P. RH~NEs, National Center for Atmospheric Research A. R. SEEBASS III, University of Colorado S. WE~NsAuM, The City College, City University of New York F. A. Wars, Princeton University Subpanel on General Plasma Physics N. ROSTOKER, University of California, Irvine, Chairman G. BEREFT, Massachusetts Institute of Technology J. CALLEN, University of Wisconsin Madison F. CHEN, University of California, Los Angeles K. GENTLE, University of Texas at Austin H. GRIEM, University of Maryland, College Park C. Lou, University of Maryland, College Park T. O'NE~, University of California, San Diego . . .
T. ROMESSER, TRW Systems P. SPRANGLE, Naval Research Laboratory Subpanel on Fusion Plasma Confinement and Heating P. H. RUTHERFORD, Princeton University Plasma Physics Laboratory, Chairman D. E. BA~Dw~N, Lawrence Livermore National Laboratory H. L. BERK, University of Texas A. H. BOOZER, Princeton University Plasma Physics Laboratory R. W. Gould, California Institute of Technology W. L. KRUER, Lawrence Livermore National Laboratory R. K. L~NFoRD, Los Alamos National Laboratory M. PoRKo~As, Massachusetts Institute of Technology R. F. POST, Lawrence Livermore National Laboratory B. H. RIPIN, Naval Research Laboratory J. SHEFFIELD, Oak Ridge National Laboratory J. W. VAN DAM, University of Texas Subpanel on Space and Astrophysical Plasma Physics C. F. KENNEL, University of California, Los Angeles, Chairman J. ARONS, University of California, Berkeley R. BEANDFORD, California Institute of Technology F. CoRoN~T~, University of California, Los Angeles M. IsRAE~, Washington University L. LANzERoTT~, AT&T Bell Laboratories A. LIGHTMAN, Smithsonian Astrophysical Observatory K. PAPADOPOULOS, University of Maryland R. ROSNER, Harvard University F. SCARF, TRW Systems 1V
PHYSICS SURVEY COMMITTEE WILLIAM F. BRINKMAN, Sandia National Laboratories, Chairman JOSEPH CERNY, University Of California, Berkeley, and Lawrence Berkeley Laboratory RONALD C. DAVIDSON, Massachusetts Institute Of Technology JOHN M. DAWSON, University Of California, Los Angeles MILDRED S. DRESSEEHAUS, Massachusetts Institute Of Technology VAL L. FITCH, Princeton University PAUL A. FLEURY, AT&T Bell Laboratories WILLIAM A. FOWLER, W. K. Kellogg Radiation Laboratory THEODOR W. HANSCH, Stanford University VINCENT JACCARINO, University of California, Santa Barbara DANIEL KEEPPNER, Massachusetts Institute of Technology AEEXE} A. MARADUDIN, University of California, Irvine PETER D. MACD. PARKER, Yale University MARTIN L. PERK, Stanford University WATT W. WEBB, Cornell University DAVID T. WILKINSON, Princeton University DONALD C. SHAPERO, StaffDirector ROBERT L. RIEMER, Sta~Of~cer CHARLES K. REED, Consultant v
BOARD ON PHYSICS AND ASTRONOMY HANS FRAUENFEEDER, University of Illinois, Chairman FELIX H. BOEHM, California Institute of Technology RICHARD G. BREWER, IBM San Jose Research Laboratory DEAN E. EASTMAN, IBM T.J. Watson Research Center JAMES E. GUNN, Princeton University LEO p. KADANOFF, The University of Chicago w. CARE LINEBERGER, University of Colorado NORMAN F. RAMSEY, Harvard University MORTON s. ROBERTS, National Radio Astronomy Observatory MARSHALL N. ROSENBEUTH, University of Texas at Austin WILLIAM p. SLIGHTER, AT&T Bell Laboratories SAM B. TREIMAN, Princeton University DONALD c. SHAPERO, Sta~Director ROBERT L. RIEMER, Sta~O~icer HELENE PATTERSON, Sta~Assistant SUSAN WYATT, Sta~Assistant V1
COMMISSION ON PHYSICAL SCIENCES, MATHEMATICS AND RESOURCES HERBERT FRIEDMAN, National Research Council, Chairman THOMAS D. BARROW, Standard Oi1 Company (Retired) ELKAN R. BLOUT, Harvard Medical School WILLIAM BROWDER, Princeton University BERNARD F. BURKE, Massachusetts Institute Of Technology GEORGE F. CARRIER, Harvard University CHARLES L. DRAKE, Dartmouth College MILDRED S. DRESSEEHAUS, Massachusetts Institute of Technology JOSEPH L. FISHER, Office Of the Governor, Commonwealth Of Virginia JAMES C. FLETCHER, University Of Pittsburgh WILLIAM A. FOWLER, California Institute of Technology GERHART FRIEDEANDER, Brookhaven National Laboratory EDWARD D. GOLDBERG, Scripps Institution of Oceanography MARY L. GOOD, Signal Research Center J. Ross MACDONALD, University of North Carolina THOMAS F. MALONE, Saint Joseph College CHARLES J. MANKIN, Oklahoma Geological Survey PERRY L. MCCARTY, Stanford University WILLIAM D. PHILLIPS, Mallinckrodt, Inc. ROBERT E. SIEVERS, University of Colorado JOHN D. SPENGEER, Harvard School of Public Health GEORGE W. WETHERIEE, Carnegie Institution of Washington RAPHAEL G. KASPER, Executive Director LAWRENCE E. MCCRAY, Associate Executive Director . . V11
Preface This survey of plasma physics and fluid physics briefly describes present activities and recent major accomplishments. It also identifies research areas that are likely to lead to advances during the next decade. Plasma physics is divided into three major areas: general plasma physics, fusion plasma confinement and heating, and space and astro- physical plasmas. Fluid physics is treated as one topic, although it is an extremely diverse research field ranging from biological fluid dynamics to ship and aircraft performance to geological fluid dynamics. Subpanels, chosen for their technical expertise and scientific breadth, reviewed each of the four areas. The entire survey was coordinated and supervised by an Executive Committee, which is also responsible for the Executive Summary of this volume. Wherever possible, input from recent Advisory Committees was used, e.g., from the Magnetic Fusion Advisory Committee, the Space Science Board, and the Astronomy Survey Committee. This volume is organized as follows: Chapter 1 is an Introduction and Executive Summary that outlines (a) major findings and recommenda- tions; (b) significant research accomplishments during the past decade and likely areas of future research emphasis; and (c) a brief summary of present funding levels, manpower resources, and institutional in- volvement. The subpanel reports constitute Chapters 2-5 of this volume, including Fluid Physics (Chapter 2), General Plasma Physics 1X
X PREFACE (Chapter 3), Fusion Plasma Confinement and Heating (Chapter 4), and Space and Astrophysical Plasmas (Chapter 51. An important conclusion of this survey is that both plasma physics and fluid physics are scientifically and intellectually well developed, and both areas are broad subdisciplines of physics. We therefore recommend that future physics surveys have separate volumes on the physics of plasmas and the physics of fluids. Finally, we are grateful for the technical contributions and consci- entious efforts of the individual subpanel members. In addition, we wish to thank the many expert readers who have reviewed this report and provided useful suggestions that improved the document. The readers include Stirling Colgate, John Deutch, Herman Feshbach, George Field, William Fowler, Edward Frieman, Harold Furth, Hans Griem, Robert Gross, Donald Kerst, Hans Liepmann, Jeremiah Ostriker, Eugene Parker, David Pines, Marshall Rosenbluth, Ascher Shapiro, Joseph Smagorinsky, and Edward Stone. We appreciate their valuable contributions.
Contents 1 INTRODUCTION AND EXECUTIVE SUMMARY General Findings and Recommendations, Findings, ~ Recommendations, 2 Introduction, 3 The Emergence of Plasma Physics, 3 Classification of Plasmas, 6 Fluid Physics, ~ Principal Findings and Recommendations, 10 General Plasma Physics, :10 Fusion Plasma Confinement and Heating, Magnetic Confinement, Inertial Confinement, 13 Space and Astrophysical Plasmas, 14 Fluid Physics, :16 Recent Accomplishments and Future Research Opportunities, IS General Plasma Physics, :18 Significant Recent Accomplishments, 18; Future Research Opportunities, 19 Fusion Plasma Confinement and Heating, 20 Significant Recent Accomplishments Magnetic X1
. . Xll CONTENTS Confinement, 20; Future Research Opportunities Magnetic Confinement, 22; Significant Recent Accomplishments- Inertial Confinement, 24; Future Research Opportunities Inertial Confinement, 25 Space and Astrophysical Plasmas, 26; Significant Recent Accomplishments, 26; Future Research Opportunities, 27 Fluid Physics, 28 Significant Recent Accomplishments, 28; Future Research Opportunities, 30 Funding and Manpower Resources, 32 Institutional Involvement, 32 General Plasma Physics, 32 Plasma Confinement and Heating, 33 Space and Astrophysical Plasmas, 34 Fluid Physics, 35 2 FLUID PHYSICS . Introduction and Overview, 36 Significant Accomplishments and Opportunities in Fluid Physics, 38 Significant Recent Accomplishments, 38 Significant Research Opportunities, 40 Findings and Recommendations 42 Principal Findings, 42 Support Structure, 42; Computational Techniques, 43; Instrumentation Techniques, 43; Education, 43 Principal Recommendations, 44 Research Support, 44; Education, 45 Government Support, Manpower, and University Research, 45 Detailed Review of the Branches, Selected Topical Subject Areas, and Technical Disciplines of Fluid-Physics Research, 48 Branches of Fluid Physics, 48 Combustion and Reacting Flows, 48; Non-Newtonian Fluids and Rheology, 51; Vortex-Dominated Flows, 53; High-Speed Flows, 55; Molecular and Statistical Phenomena, 56; Viscosity-Dominated Flows, 57; Stability, 60; Turbulence, 62; Bouyancy-Driven . 36
. . . CONTENTS XIli Motion, 66; Interface Phenomena, 67; Sound Generation and Propagation, 69; Radiation Hydrodynamics, 70; Porous Media, 72; Rotating Phenomena, 73; Phase Change, 74 Topical Subject Areas, 76 Aerodynamics, 76; Biofluid Dynamics, 81; Flows of Electrically Conducting Fluids, 83; Geophysical Fluid Dynamics, 84; Multiphase Flows, 86 Technical Disciplines, 88 Modeling and Analytical Methods, 88; Computational Fluid Dynamics, 89; Experimental Methods, 91 Acknowledgments, 94 3 GENERAL PLASMA PHYSICS . Scope and Objectives of General Plasma Physics, 95 Intense Beams Electrons, Ions, and Photons, 97 Development of Low-Impedance Multiterawatt Machines, 98 Intense Ion Beams, 98 Development of High-Energy, High-Current Machines, 99 Z-Pinch X-Ray Sources, 99 Propagation of Charged-Particle Beams in Gas and Plasma, 99 Expectations and Recommendations for the Next :10 Years, 100 Collective Accelerators, 101 Space-Charge Accelerators, 102 Wave Accelerators, 102 Electron-Ring Accelerators, 102 Collective Focusing Accelerators, 103 Laser-Driven Accelerators, 103 Beat-Wave Accelerator, 104 Inverse Free-Electron-Laser Accelerator, 105 Grating Accelerator, 105 High-Gradient Structures, 105 Inverse Cerenkov Accelerator, 105 Cyclotron Resonant Accelerator, 105 · 95
XIV CONTENTS Problem Areas, 106 Recommendations for the Next 10 Years, 106 Coherent, Free-Electron Radiation Sources, 107 Electromagnetic Wave-Plasma Interaction, ~ ~ ~ Scattering and Absorption of Electromagnetic Waves by Plasmas, Isotope Separation, ~ 14 Nonlinear Phenomena in Plasmas, ~ 16 Chaos in Hamiltonian Systems, Il6 Soliton and Related Phenomena, Il7 Strong Langmuir Turbulence, ~ IS Parametric Instabilities, ~ IS Magnetic Reconnection, IlS Turbulent Relaxation to Force-Free States, ~ 19 Other Major Achievements in the Past Decade, 120 Plasma Theory Developments Related to Magnetic Confinement, 120 Magnetic-Flux Geometries and Coordinate Systems, 121 Single-Particle Orbits, :121 Coulomb Collisional Processes, 122 Macroscopic Equilibria, 122 Macroscopic Instabilities Ideal Magnetohydrodynamics, 122 Macroscopic Instabilities Resistive Magnetohydrodynamics, 123 Microscopic (Kinetic) Instabilities and Turbulent Transport, :123 Summary, 124 Atomic Physics in (and for) Plasmas, 124 Recent Progress, 125 Outstanding Research Problems, 126 Recommendations, 126 Training, 127 Funding Levels, 128 Recommended Funding Levels, 128 Plasma Diagnostics, 128 Laser Scattering, 130
CONTENTS XV Microwave Interferometry, :130 Spectroscopy, 130 Charge Exchange, 131 Neutrons and Alpha Particles, 131 Blackbody and Plasma-Well Interactions, 132 Heavy-Ion Diagnostics, 132 Time-Resolved Plasma Activity, 132 Scattering from Collective Fluctuations, 133 Data Acquisition and Instrumentation, 133 Desiderata, 134 Strongly Coupled Plasma Physics, 136 History, :136 Recent Progress, 138 Outlook for the Next 10 Years, 139 Nonneutral Plasmas, 140 4 FUSION PLASMA CONFINEMENT AND HEATING 144 Scope and Objectives of Fusion Plasma Research, 144 Introduction, 144 The Fusion Process, 146 Magnetic Confinement, 150 Inertial Confinement, 154 Tokamak and StelIarator Magnetic-Confinement Systems, 156 Introduction, 156 Major Advances, 161 Optimization of Experimental Performance, 161; Confinement, 163; Stability and Beta Limits, 166 Current Frontiers of Research, 168 Prospects for Future Advances, 17:t Magnetic Mirror Systems, 172 Introduction, 172 Major Advances the Tandem Mirror, :174 Current Frontiers of Research, 176 Microstability, 177; Axial Confinement: Control of the Potential Profile and Thermal Barriers, 178; Macrostability: Equilibrium and Beta Limits, 181; Radial Confinement: Particle Transport and Radial Potential Control, 183
XVI CONTENTS Prospects for Future Advances in Mirror Confinement, i84 Elmo Bumpy Torus, IS5 Introduction, I85 Major Advances, 187 Current Frontiers of Research, I88 Prospects for Future Advances, I89 Reversed-Field Pinch, 190 Introduction, 190 Major Advances, 192 Current Frontiers of Research, 193 Prospects for Future Advances, 194 Compact Toroids, 195 Introduction, 195 Major Advances, 198 Spheromaks, 199; Field-Reversed Configurations, 201 Current Frontiers of Research, 201 Prospects for Future Advances, 203 Plasma Heating, 204 Introduction, 204 Radio-Frequency Heating, 204 Major Advances: Theory, 206; Major Advances: Experiment, 207; Prospects for Future Advances, 210 Radio-Frequency Current Drive, 212 Major Advances: Theory, 213; Major Advances: Experiment, 213; Prospects for Future Advances, 216 Neutral-Beam Heating, 216 Major Advances, 217; Prospects for Future Advances, 219 :Inertial-Confinement Fusion Systems, 221 Introduction, 221 Major Advances, 224 Drivers for Inertial-Confinement Fusion, 224; Laser-Target Physics, 226 Current Frontiers of Research, 228 Laser-Plasma Coupling, 228; Heat Transport and Ablation, 231; Shell Acceleration, Uniformity, and Hydrodynamic Instabilities, 233 Prospects for Future Advances, 235 Advanced Fusion Applications, 236
CONTENTS Xvii Funding of Fusion Plasma Research in the United States, 238 Principal Findings and Recommendations, 240 Magnetic Confinement, 240 Inertial Confinement, 241 Acknowledgments, 242 5 SPACE AND ASTROPHYSICAL PLASMAS Principal Conclusions, 243 Principal Recommendations, 244 Introduction, 245 Relationship Between Laboratory, Space, and Astrophysical Plasma Research, 246 Definition of Space and Astrophysical Plasma Physics, 246 Relationship Between Laboratory and Space Plasma Physics, 246 Relationship Between Space and Astrophysical Plasma Research, 247 Magnetohydrodynamic Atmospheres and Winds, 248; Planetary and Astrophysical Magnetospheres, 249; Magnetic Field Reconnection, 252; Particle Acceleration and Cosmic Rays, 254 The Unifying Physical Problems, 255 Space and Astrophysical Plasma Physics in the Past 10 Years, 255 Problem 3: The Behavior of Large-Scale Plasma Flows, 256 Planetary Magnetospheres, 256; Dynamics of the Earth's Magnetosphere, 256; Magnetohydrodynamic Structures in the Sun's Atmosphere and in the Solar Wind, 256; Magnetospheres of Neutron Stars, 257; Magnetohydrodynamic Jets, 257; General Relativistic Electrodynamics, 259 Problem I: Reconnection, 259 Problem 2: Interaction of Turbulence with Magnetic Fields, 259 Problem 4: Acceleration of Energetic Particles, 260 Problem 5: Particle Confinement and Transport, 261 Problem 6: CollisionIess Shocks, 261 Problem 7: Beam-Plasma Interactions, and the Generation of Radio Emissions, 262 · . . 243
. . . XV111 CONTENTS Problem 8: Interactions Between Plasmas and Neutral Gases, 262 Space and Astrophysical Plasma Physics in the Next 10 Years, 263 Impact of Research on Space and Astrophysical Plasmas, 264 The Role of Space and Ground-Based Measurements and Observations, 266 Solar-System Plasma Physics, 266 Astrophysical Plasma Physics, 267 In Situ Measurements near the Sun, 268 Concluding Remarks, 269 The Roles of Laboratory and Active Space Experiments, 269 Laboratory Experiments, 269 Active Space Experiments, 270 The Role of Theory, 271 Space Plasma Theory, 271 Theoretical Astrophysics, 272 The Role of Numerical Models and Simulations, 273 Why Quantitative Models are Essential, 273 System Models and Process Simulations in the Next Decade, 275 System Models, 275; Process Simulations, 276; Overall Conclusions, 277 Proposal for a Dedicated, Advanced Computational Program, 278 The Role of Plasma Physics in the University Curriculum, 279 Space Plasma Physics, 279 Astrophysical Plasma Physics, 280 Plasma Physics in General, 281 References, 282 GLOSSARY. INDEX . . 283 . 307