Plasma Astrophysics: Kinetic Processes in Solar and Stellar Coronae

by Arnold O. Benz

Overview

This textbook is a basic introduction to kinetic plasma phenomena in solar and stellar coronae. The author unifies observations and theory which gives a wide perspective to the subject. An important feature is the lucidly written presentation of the fundamentals of plasma physics. The basic theory developed is then extended to some exemplary and important observations of coronal dynamics, such as coronal current, particle acceleration, propagation of particle beams, and shocks.
The book has grown from the author's introductory courses on plasma astrophysics at the Swiss Federal Institute of Technnology (ETH). it addressed advanced undergraduates and first-year graduate students without a background in plasma physics. It will also be of interest to more senior research workers involved in coronal physics, solar/stellar winds, and various other fields of plasma astrophysics. Problems suitable for class use are included at the end of each chapter.

Product Details

ISBN-13:	9780792324294
Publisher:	Springer-Verlag New York, LLC
Publication date:	09/01/1993
Series:	Astrophysics and Space Science Library Series , #18
Pages:	320
Product dimensions:	6.14(w) x 9.21(h) x 0.75(d)

Table of Contents

	Preface	xv
Chapter 1.	Introduction	1
1.1.	The Solar Corona	2
1.1.1.	Brief Overview of the Sun	2
1.1.2.	Optical Observations of the Corona	4
1.1.3.	Soft X-Rays and EUV Lines	4
1.1.4.	Thermal Radio Emissions	5
1.2.	Dynamic Processes	7
1.2.1.	Processes in the Upper Corona	7
1.2.2.	Processes in the Lower Corona	7
1.2.3.	Solar Flares	8
1.2.4.	Other Dynamic Processes	9
1.3.	Stellar Coronae	11
1.3.1.	Soft X-Ray Emission	11
1.3.2.	Stellar Flares	12
1.3.3.	Quiescent Radio Emission	14
1.4.	Fundamental Equations	15
1.4.1.	Magnetohydrodynamic Approach	17
1.4.2.	Kinetic Approach	18
	Further Reading and References	21
Chapter 2.	Basic Concepts	22
2.1.	Single Particle Orbit	22
2.1.1.	Homogeneous Magnetic Field	22
2.1.2.	Inhomogeneous Magnetic Field	25
2.1.3.	Conservation of the Magnetic Moment	26
2.1.4.	Particle Drifts	27
A.	Electric Field	29
B.	Gravitational Field	29
C.	Curved Field Lines	29
2.2.	Particle Trapping in Magnetic Fields	30
2.3.	Generation of Beams	33
2.4.	Debye Shielding	35
2.5.	Charge Oscillations and the Plasma Frequency	38
2.6.	Collisions	40
2.6.1.	Particle Encounters in a Plasma	40
2.6.2.	Fokker-Planck Method	42
2.6.3.	Collision Times	43
A.	Angular Deflection	43
B.	Energy Exchange	45
C.	Momentum Loss	46
D.	Energy Loss	46
E.	Discussion	48
F.	Thermal Collision Times	49
	Exercises	49
	Further Reading and References	50
Chapter 3.	Magnetohydrodynamics	51
3.1.	Basic Statistics	51
3.1.1.	Boltzmann Equation	51
3.1.2.	Velocity Moments of the Boltzmann Equation	52
A.	Conservation of Particles	53
B.	Conservation of Momentum	53
C.	Conservation of Energy	54
3.1.3.	Elementary Magnetohydrodynamics (MHD)	55
A.	MHD Equations and Approximations	56
B.	Electric Fields	58
C.	MHD Properties	58
3.2.	MHD Waves	61
3.2.1.	Linearization	61
3.2.2.	Dispersion Relation and Polarization (Parallel Propagation)	62
3.2.3.	Perpendicular Propagation	65
3.2.4.	General Case	66
	Exercises	67
	Further Reading and References	68
Chapter 4.	Waves in a Cold, Collisionless Plasma	69
4.1.	Approximations and Assumptions	69
4.2.	Cold Plasma Modes	71
4.2.1.	Linearization	71
4.2.2.	Ohm's Law	73
4.2.3.	Dielectric Tensor	74
4.2.4.	Dispersion Relation	75
4.3.	Parallel Waves	76
4.3.1.	Electrostatic Waves	76
4.3.2.	Electromagnetic Waves	77
4.3.3.	Dispersion Relations of the L and R Waves	78
4.3.4.	Resonances at the Gyrofrequencies	79
4.3.5.	Cutoffs Near [omega subscript p]	80
4.4.	Perpendicular Propagation	81
4.4.1.	Electrostatic Waves	81
4.4.2.	Electromagnetic Waves	82
4.5.	Oblique Propagation and Overview	83
4.6.	Beam Mode	85
	Exercises	87
	Further Reading and References	88
Chapter 5.	Kinetic Plasma and Particle Beams	89
5.1.	Radio Observations of Solar Electron Beams	89
5.1.1.	Radio Instruments	92
5.1.2.	Type III Radio Bursts	93
5.2.	Waves and Instability in Kinetic Plasmas	94
5.2.1.	Singularities	98
5.2.2.	Dispersion Relation	100
A.	Principal Part	100
B.	Singular Point	100
5.2.3.	Landau Damping	101
5.2.4.	Bump-on-Tail Instability	102
5.2.5.	Cerenkov Resonance	103
5.2.6.	Ion Acoustic Waves	104
5.2.7.	Thermal Level of Waves	106
5.3.	Plasma Waves in the Solar Corona	107
5.3.1.	Plasma Density	107
5.3.2.	Drift	108
5.3.3.	Field Geometry	109
A.	U-Bursts	109
B.	Magnetic Field Configuration Near Acceleration	111
C.	Interplanetary Space	111
5.3.4.	Decay Time	112
5.3.5.	Other Radio Wave Emitting Beams	113
	Exercises	113
	Further Reading and References	114
Chapter 6.	Astrophysical Electron Beams	115
6.1.	The Beam-Plasma System	115
6.1.1.	Magnetically Driven Return Current	116
6.1.2.	Electrostatic Return Current	119
6.2.	Non-Linear Evolution and Saturation	120
6.2.1.	Quasi-Linear Diffusion	122
6.2.2.	Strong Turbulence	124
6.2.3.	Deflection of Electrostatic Waves	126
6.2.4.	Summary	127
6.3.	Plasma Emission	127
6.3.1.	Harmonics	127
6.3.2.	Phonons and Their Scattering (Wave Conversion)	129
A.	Spontaneous Scattering off Ions	130
B.	Induced Scattering	131
C.	Scattering off Other Waves	132
6.3.3.	Plasma Radiation Emissivities	135
A.	Emission at the Harmonic	135
B.	Emission at the Fundamental: Scattering off Ions	136
C.	Emission at the Fundamental: Decay	137
6.3.4.	Sense of Polarization	139
6.3.5.	Magnetic Field Strength in the Corona	140
6.4.	Hard X-Ray Emission of Beams	142
6.4.1.	Emission Process	142
6.4.2.	Observations	144
6.4.3.	X-Rays from Beams	145
6.4.4.	Radio - Hard X-Ray Association	147
6.4.5.	Diagnostics of the Accelerator	147
A.	Energy of Flare Electrons	148
B.	Fragmentation of Flares	150
	Exercises	151
	Further Reading and References	152
Chapter 7.	Ion Beams and Electromagnetic Instabilities	154
7.1.	Observations of Energetic Ions	154
7.1.1.	Solar Ion Beams	154
7.1.2.	Cosmic Rays	156
7.1.3.	Ion Beams Near Earth	158
7.2.	Electromagnetic Instabilities of Velocity Space Anisotropy	158
7.2.1.	Fire-Hose Instability	159
7.2.2.	Kinetic Instability	160
A.	Dispersion Relation of Transverse Waves in Kinetic Plasma	160
B.	Resonance Condition	163
C.	Wave-Particle Interaction	164
D.	Growth Rate	166
7.3.	Applications to Ion Beams	168
7.3.1.	Instability Threshold	168
7.3.2.	Wave Growth	169
7.3.3.	Ion Beam Propagation	170
A.	Deflection Time	171
B.	Diffusive Propagation	172
7.4.	Electrostatic Ion Beam Instabilities	174
7.4.1.	Low-Frequency Waves	174
7.4.2.	High-Frequency Waves	175
	Exercises	175
	Further Reading and References	176
Chapter 8.	Electrons Trapped in Magnetic Fields	177
8.1.	Observational Motivation	178
8.1.1.	Incoherent Solar Emissions	178
8.1.2.	Synchrotron Emission	179
8.1.3.	Narrowband Spikes	182
8.2.	Loss-Cone Instabilities	184
8.2.1.	Low-Frequency Electromagnetic Instability	184
8.2.2.	High-Frequency Waves and Cyclotron Masers	186
A.	Linear Growth Rates	186
B.	Particles in Resonance	188
C.	Resonance Curve	190
D.	Loss-Cone Instabilities	191
8.3.	Precipitation of Trapped Particles	194
8.3.1.	Weak and Strong Diffusion	194
8.3.2.	Diffusion Time	195
A.	Collisions	195
B.	Quasi-Linear Diffusion	195
8.3.3.	Equilibrium of Quasi-Linear Diffusion	196
8.3.4.	Dominant Waves	197
8.4.	Observations of Trapped Electrons	198
8.4.1.	Injection Dominated	198
8.4.2.	Trapping and Resupply	198
A.	Moving Type IV Bursts	199
B.	Stationary Metric Type IV Bursts	202
C.	Decimetric Bursts	202
8.4.3.	Depletion Dominated	203
8.4.4.	Stellar Emissions by Trapped Electrons	205
A.	Quiescent Radio Emission	205
B.	Stellar Flares	207
	Exercises	209
	Further Reading and References	210
Chapter 9.	Electric Currents	212
9.1.	Origin of Currents in Coronae	212
9.1.1.	MHD Generator	213
9.1.2.	Current Sheet	214
9.2.	Classical Conductivity and Particle Acceleration in Stable Currents	215
9.2.1.	Conductivity	216
9.2.2.	Runaway Electrons	217
9.3.	Instabilities of Electric Currents	220
9.3.1.	Parallel Currents	220
A.	Ion Cyclotron Instability	220
B.	Buneman Instability	220
C.	Ion Acoustic Instability	221
9.3.2.	Perpendicular Currents	222
9.4.	Anomalous Conductivity, Heating, and Acceleration	223
9.4.1.	Anomalous Conductivity	223
9.4.2.	Ohmic Heating	224
9.4.3.	Particle Acceleration	225
A.	Runaway Particles	225
B.	Resonance Acceleration	226
9.5.	Observing Currents	227
9.5.1.	Currents in the Photosphere	227
9.5.2.	Noise Storms	228
9.5.3.	Radio Emission of Low-Frequency Turbulence	230
	Exercises	232
	Further Reading and References	233
Chapter 10.	Collisionless Shock Waves	234
10.1.	Elementary Concepts	235
10.1.1.	Types of Shocks	235
10.1.2.	Conservation Equations (MHD Shocks)	238
10.2.	Collisionless Shocks in the Solar System	241
10.2.1.	Planetary and Cometary Bow Shocks	241
A.	Non-Thermal Particles	242
B.	Upstream Waves	243
10.2.2.	Interplanetary Shocks	245
10.2.3.	Coronal Shocks	246
A.	Coronal Mass Ejection	246
B.	Type II Radio Bursts	247
10.3.	Particle Acceleration and Heating by Shocks	249
10.3.1.	Electron Acceleration at Quasi-Perpendicular Shocks	249
A.	De Hoffmann-Teller Frame	250
B.	Electron Acceleration	251
10.3.2.	Ion Acceleration at Quasi-Parallel Shocks	253
10.3.3.	Resonant Acceleration and Heating by Shocks	254
10.4.	Stochastic Particle Acceleration	255
	Exercises	257
	Further Reading and References	259
Chapter 11.	Propagation of Radiation	260
11.1.	Transfer Equation	261
11.2.	Collisional Absorption	264
11.3.	Dispersion Effects	266
11.3.1.	Geometric Optics	266
11.3.2.	Plasma Dispersion	268
11.3.3.	Faraday Rotation	269
11.3.4.	Quasi-Transverse Regions	271
A.	Mode Coupling in Quasi-Transverse Regions	272
B.	Confrontation with Observations	274
C.	Depolarization	275
11.4.	Scattering at Plasma Inhomogeneities	275
11.5.	Propagation in a Fibrous Medium	278
11.5.1.	Ducting	279
11.5.2.	Anisotropic Scattering	281
	Exercises	282
	Further Reading and References	283
Appendix A.	Mathematical Expressions	284
Appendix B.	Units	286
Appendix C.	Frequently Used Expressions	287
Appendix D.	Notation	289
	Author Index	292
	Subject Index	295

Editorial Reviews

The author presents a basic introduction to the subject, including both theory and observation. The fundamentals of plasma physics are discussed, then the basic theory extended to some observations of coronal dynamics, such as coronal current, particle acceleration, propagation of particle beams, and shocks. Topics include magnetohydrodynamics; waves in a cold, collisionless plasma; kinetic plasma and particle beams; astrophysical electron beams; ion beams and electromagnetic instabilities; and electrons trapped in magnetic fields. Exercises are included. Annotation c. Book News, Inc., Portland, OR (booknews.com)

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