Impact Spectropolarimetric Sensing

This book arises from the significant quantity of original results in the field of impact spectropolarimetry, mainly for solar flare studies, and the evident potential applications of this technique to environmental physics, astrophysics, and hot plasma. This is a practically oriented book, describing theoretical fundamentals and implementation of this new interdisciplinary remote sensing technique. A basic phenomenon for impact spectropolarimetric sensing is the polarization ofthe electron shells of an ensemble of free atomic particles (atoms, ions, molecules) due to collisional interaction. Slow collisions in the presence of internal anisotropies in the relative velocity space inside any ionized medium, as well as bombardment of a diluted gas by fast precipitating light projectiles, are analyzed in detail as principal impact polarization mechanisms. Impact spectro polarimetric sensing incorporates state-of-the-art theoretical methods of colli sional physics in combination with reliable polarimetric measurements. This technique is illustrated by the new quantitative sensing of energy transport to the upper region of the chromosphere during solar flares, making use of ground based solar spectropolarimetric observations. Apart from general astrophysical and solar-terrestrial significance, a solar flare, the brightest nonthermal phenomenon, is a good candidate for the demonstration of new opportunities of impact spectropolarimetry. New astrophysical achievements of quantitative spectropolarimetry are particularly considered in this book. The theoretical part presents a quantum mechanical description of impact polarization and the spectropolarimetric manifestations for different energies of the colliding partners.

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1. Physical Introduction: Concepts, Phenomenology, Retrospectives, Applications.- 1.1. Polarization of Atomic Ensembles in Ionized Media.- 1.2. Polarization of Solar Flare Emission.- 1.3. Impact Polarization.- 1.4. Gas Discharge Studies.- 1.5. Collisional Kinetics of Polarization.- 1.6. Spectropolarimetric Sensing.- 1.7. Polarization Effects in the Earth Atmosphere.- 2. Polarization of a Photon Beam.- 2.1. Introduction.- 2.2. Wave Function of a Photon.- 2.3. Momentum, Spin, and Parity of a Photon.- 2.4. Rotation Matrix.- 2.5. Spinors.- 2.6. Relationship between the Polarization Direction and Characteristics of a Photon.- 2.7. Relationship between Stokes Parameters and the Characteristics of an Optical Field.- 2.8. Concluding Remarks.- 3. Theory of Collisional Spectropolarimetric Effects.- 3.1. Introduction.- 3.2. Density Matrix of an Atomic Ensemble.- 3.3. Polarization Density Matrix.- 3.4. Polarization Moments of the Density Matrix.- 3.5. Physical Meaning of Polarization Moments.- 3.6. Polarization Moments and Spectral Characteristics of an Atomic Ensemble.- 3.7. Density Matrix Relaxation Theory.- 3.8. Collisional Evolution of Polarization Moments.- 3.9. Interaction with an Electromagnetic Field.- 3.10. Impact Alignment Cross Section.- 3.11. Anisotropic Collisional Relaxation of Excited Hydrogen Atoms.- 3.12. Spectropolarimetric Effects for Angular Correlation Experiments.- 3.13. Concluding Remarks.- 4. Fast Particle Collision with a Heavy Atomic Target.- 4.1. Introduction.- 4.2. Born Expansion of the Scattering Amplitude.- 4.3. The Glauber Approximation.- 4.4. The System of Impact Parameter Equations.- 4.5. Concluding Remarks.- 5. Theory of Anisotropic Collisional Relaxation.- 5.1. Introduction.- 5.2. Symmetry of the Collisional Relaxation Cross Section Matrix.- 5.3.Rate Constants of Collisional Relaxation in Case of Partial Anisotropy.- 5.4. Distribution Functions of Relative Velocities.- 5.5. Collisional Relaxation of Polarization Moments under Intermultiplet Mixing.- 5.6. Anisotropie Collisional Alignment of a Narrow Multiplet.- 5.7. Anisotropie Relaxation and Polarization of Light.- 5.8. Depolarizing Collisions with Charged Particles.- 5.9. Concluding Remarks.- 6. Theory of Charge Exchange Polarization.- 6.1. Introduction.- 6.2. Theory of an Electron in the Field of Two Coulomb Centers.- 6.3. Distorted Wave Approximation Theory.- 6.4. Pseudolevel Technique for Computing the Polarization of Ions.- 6.5. Concluding Remarks.- 7. Spectropolarimeters for Solar Problems.- 7.1. Introduction.- 7.2. Spectropolarimetric Techniques of Meudon Observatory (France).- 7.3. Polarimetric Observations in the Crimean Astrophysical Observatory (Ukraine).- 7.4. The Spectropolarimeter of the Institute of Solar and Terrestrial Physics (Irkutsk, Russia).- 7.5. Solar Spectropolarimeter of Sacramento Peak Observatory (USA).- 7.6. Concluding Remarks.- 8. Solar Flare Observations at the Crimean Astrophysical Observatory (Ukraine).- 8.1. Introduction.- 8.2. Technique of Observation and Data Processing.- 8.3. Degree of Polarization along the Hydrogen H? Line.- 8.4. Spatial Distribution of the Degree of Polarization.- 8.5. Orientation of the Polarization Plane.- 8.6. Concluding Remarks.- 9. Observations of Polarization Effects at the Irkutsk Institute of Solar and Terrestrial Physics (Russia).- 9.1. Introduction.- 9.2. Spectropolarimetric Parameters of H? and H? Lines for the Flare on 15.09.1981.- 9.3. Spectropolarimetric Parameters of the Active Region 5669 (SGD) on 07.09.1989.- 9.4. Detection of the Linear Polarization of the Flare on 16.05.1991.- 9.5.Concluding Remarks.- 10. Solar Flare Observations at Meudon Observatory (France).- 10.1. Introduction.- 10.2. Linear Polarization of Emission of the Flare on 17.05.1980.- 10.3. Spectropolarimetric Effects of the Flare on 15.07.1980.- 10.4. Spectropolarimetric Features of Three Flares on 11.07.1982.- 10.5. Polarization Effects of the Emission of Two Flares on 17.07.1982.- 10.6. Concluding Remarks.- 11. Spectropolarimetric Measurements of Mustaches.- 11.1. Introduction.- 11.2. Polarization of Emission of Mustaches near the Solar Limb.- 11.3. Spectropolarimetric Measurements of Mustaches with an H? Filter.- 11.4. Improved Spectropolarimetric Observations of Mustaches on 14.11.1985.- 11.5. Observations of Mustaches at Baikal Astrophysical Observatory.- 11.6. Observations of Mustaches at Sacramento Peak Observatory.- 11.7. Concluding Remarks.- 12. Methodology of Impact Spectropolarimetric Sensing.- 12.1. Introduction.- 12.2. Spectropolarimetric Sensing Using Ground-Based Observations.- 12.3. Role of the Solar Magnetic Field.- 12.4. Linear Polarization of H? and H? Hydrogen Lines in the Born Approximation.- 12.5. Linear Polarization of the H? Hydrogen Line in the Glauber Approximation.- 12.6. Linear Polarization of H? and H? Hydrogen Lines by the Impact Parameter Method.- 12.7. Linear Polarization of the L? Hydrogen Line.- 12.8. Concluding Remarks.- 13. Impact Spectropolarimetric Diagnostics of Nonthermal Phenomena in the Solar Atmosphere.- 13.1. Introduction.- 13.2. Energy Transport into the Chromospheric Region of a Solar Flare.- 13.3. Determination of Proton Energy for the Flare on 16.05.1991.- 13.4. Impact Spectropolarimetric Sensing for the Flare on 15.09.1981.- 13.5. Impact Spectropolarimetric Sensing of Mustaches.- 13.6. Concluding Remarks.- 14. Conclusions.-References.