The Effects of Localized Thermal Pressure on Equilibrium Magnetic Fields and Particle Drifts in The Inner Magnetosphere
Abstract Localized injections of hot anisotropic plasma sheet particles into the inner magnetosphere can significantly deform the quiet time dipole‐like magnetic field and thus disturb electron and ion's drift paths and scattering rates. Although many details of magnetic field deformation can be inferred from empirical models, roles of different characteristics of injected plasma on the structure of such deformation require further investigation. In this study, we use the 2‐D axisymmetric equilibrium model to calculate self‐consistent magnetic field in force balance with a Gaussian thermal pressure distribution characterized by four input parameters: the ratio between plasma pressure and magnetic pressure ( β ) at the pressure peak β 0 , the radial location of the pressure peak L 0 , the width of the half peak pressure σ 0 , and the equatorial pressure anisotropy A e . Using the modeled magnetic field, we find that the magnetic field perturbation increases with increasing β 0 and decreasing σ 0 while the magnetic curvature perturbation increases with increasing A e , β 0 , and σ 0 and decreasing L 0 . For energetic particles the change of magnetic gradient drift motion is much greater than that of curvature drift motion. The magnetic dip structure formation requires a critical β value that increases with increasing σ 0 and decreasing L 0 . Despite the unavailability of observations in the existing literatures to check the condition of magnetic dip formation, such condition will be checked against observations as a future study. Finally, we also use 3‐D ring current‐atmosphere interactions model with self‐consistent magnetic field model to illustrate the effect of azimuthal pressure distribution, which is relevant to asymmetric ring current.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program
- Grant/Contract Number:
- 89233218CNA000001; DE‐AC52‐06NA25396
- OSTI ID:
- 1542844
- Alternate ID(s):
- OSTI ID: 1532804
- Report Number(s):
- LA-UR-18-28371
- Journal Information:
- Journal of Geophysical Research. Space Physics, Vol. 124, Issue 7; ISSN 2169-9380
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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