Neutral Current Sheets in Plasmas

ISBN-13: 9781461585664 / Angielski / Miękka / 2012 / 163 str.

N. G. Basov; N. G. Basov

Spis treści

Neutral Current Sheets in Plasmas in Space and in the Laboratory.- 1. Introduction.- 2. Production of a Quasisteady Neutral Sheet.- 3. The Neutral Sheet or Petschek Flow?.- 4. Decrease in the Plasma Density near a Neutral Sheet.- 5. Stability of a Neutral Sheet.- Literature Cited.- Hydrodynamic Plasma Flow in a Strong Magnetic Field.- I. Hydrodynamic Plasma Flow in a Strong Magnetic Field in the Absence of Null Lines.- 1. Existence of Continuous Plane (Two-Dimensional) Plasma Flows in a Strong Frozen-in Magnetic Field.- A. Formalism of Two-Dimensional MHD Problems.- B. Existence of Continuous Solutions.- C. Plasma Motion in the Field of a Plane Magnetic Dipole Which Varies with the Time.- 2. Continuous Plasma Flows in a Strong, Poloidal, Axisymmetric Magnetic Field.- A. General Formulation of the Problem.- B. Case of a Dipole Magnetic Field.- 3. Plowing of the Interstellar Medium by the Magnetic Field of an Expanding Envelope.- A. Observation of Gaseous Condensations in the Envelopes of Novae.- B. Theoretical Models.- C. Raking of the Interstellar Plasma by the Magnetic Field of the Expanding Envelope.- 4. Magnetic Raking of Plasma as a Possible Mechanism for the Formation of Certain Types of Solar Prominences.- A. Observations and Classification of Solar Prominences.- B. Theoretical Models for Surges.- C. Magnetic Raking as a Mechanism for Surges.- II. Appearance of a (Neutral) Current Sheet during Plasma Motion in the Field of a Plane Magnetic Dipole.- 1. Condition for the Absence of Continuous Two-Dimensional Plasma Flows with a Strong Frozen-in Magnetic Field; Appearance of a Current Sheet.- 2. Problem of the Appearance of a Current Sheet as a Plasma Moves in the Field of a Plane Magnetic Dipole.- A. Possible Applications of the Problem.- B. Formulation of the Problem. Field in the Absence of a Plasma.- C. Solution with a Current Sheet.- D. Discussion.- 3. Some Comments Regarding Two-Dimensional Models of the Magnetosphere.- 4. Magnetic Field of a Contracting Plasma Cylinder.- A. Magnetic Field Configuration in the Absence of a Plasma.- B. Formulation and Solution of the Problem with a Current Sheet.- 5. Three-Dimensional Problems with a Current Sheet.- III. Hydrodynamic Plasma Flow near a Current Sheet.- 1. General Formulation of the Problem.- 2. Hydrodynamic Plasma Flow near a Developing Current Sheet.- A. Asymptotic Properties of the Solution.- B. Results of Numerical Calculation.- 3. Hydrodynamic Plasma Flow near a Steady-State Current Sheet.- 4. Discussion of Results.- Literature Cited.- Numerical Integration of the MHD Equations near a Magnetic Null Line.- 1. Equations for Two-Dimensional Flow.- 2. Small-Amplitude Waves.- 3. Numerical Integration.- 4. Calculated Results and Discussion.- Literature Cited.- Kinetics of a Neutral Current Sheet.- 1. Equilibrium State.- 2. Stability of a Neutral Current Sheet.- 3. Simple Models for Charged-Particle Acceleration at Neutral Current Sheets.- 4. Model for the Decay of a Current Sheet.- Literature Cited.- Experimental Study of the Conditions for the Appearance of a Neutral Current Sheet in a Plasma: Some Characteristics of the Sheet.- I. Events which Occur as a Plasma Moves in a Magnetic Field with a Null Line.- 1. Magnetic Null Lines.- 2. Steady-State Models for the Conversion of Magnetic Energy into Plasma Energy near Null Lines.- 3. Plasma Motion near a Magnetic Null Line in the MHD Approximation.- 4. Formation of a Current Sheet as the Result of a Two-Dimensional Plasma Flow near a Magnetic Null Line.- 5. Effect of the Finite Plasma Conductivity on the Formation of a Neutral Current Sheet.- II. Experimental Apparatus for Studying the Formation of a Current Sheet near a Magnetic Null Line.- 1. Basic Requirements Which Must be Met by the Experimental Apparatus.- 2. System for Producing a Magnetic Field with a Null Line.- 3. Plasma Injection into a Magnetic Field with a Null Line.- 4. System for Producing the Induction Electric Field Ez along the Magnetic Null Line.- III. Current Profile near a Magnetic Null Line; Turbulent Plasma Resistance.- 1. Measurements of the Total Current and the Resistance of a Plasma in a Magnetic Field with a Null Line.- 2. Measurements of the Current Profile in a Plasma in a Magnetic Field with a Null Line.- 3. Measurements of the Current Distribution in a Magnetic Field with a Null Line in a Plasma with a Density n ?1013 cm-3; Possible Ways to Produce a Neutral Current Sheet.- IV. ? Discharge in a Quadrupole Magnetic Field as a Method for Producing a Dense Plasma.- 1. Influence of the Quadrupole Magnetic Field on Gas Breakdown in the Electric Field of a ? Discharge.- 2. Experiments on Gas Breakdown in a Quadrupole Field.- V. Development of a Neutral Current Sheet in a Magnetic Field with a Null Line in a Plasma with a Density n ? 2 • 1014 cm-3.- 1. Measurement of the Total Plasma Current and the Resistance. Inductance of the Plasma Circuit as a Factor Limiting the Current.- 2. Properties of a Fast Magnetosonic Wave Converging on a Magnetic Null Line.- 3. Development of a Current Sheet near a Magnetic Null Line.- 4. Production of a Neutral Current Sheet.- 5. Discussion of Experimental Results and Comparison with Theory.- Summary.- Literature Cited.