Collisonless Dynamics of the Magnetosphere
Abstract
Experiment: An energetic electron belt has been created in a laboratory terrella for the first time. Measurements indicate the trapped- electron belt to be localized in radius and have a non-Maxwellian energy distribution ranging from 10 to 40 keV. Using multiple probes, we have clearly identified drift-resonant instabilities leading to rapid radial transport. Transport in a dipole appears to require multiple modes, and its "bursty" nature suggests a profile relaxation of the energetic electrons which self-stabilizes the drift-resonant instabilities. Theory, Substorms in the magnetosphere cause the generation of major electromagnetic disturbances and energetic particles. We examine the role of the collisionless tearing-instability as a possible mechanism for substorms. Global asymptotic magnetotail equilbria which are slowly varying in the Earth-Sun direction are constructed, including all three components of the magnetic field. Some of these equilibria are analyzed for stability with respect to collisionless electron tearing modes. It is found that the ion tearing instability, which has been widely invoked as a possible trigger for substorms, does not exist. The By field is demonstrated to have a destabilizing effect on electron tearing modes. Regimes in which collisionless tearing modes can grow are delineated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1993
- Accession Number
- ADA278886
Entities
People
- Amitava Bhattacharjee
Organizations
- Columbia University