Motion of a charged particle in a nearly axisymmetric magnetic field
The motion of a charged particle in a static magnetic field is studied by means of repeated canonical transformations of a Hamiltonian system. Adiabatic invariants are generated based on the assumption that the particle larmor radius is small compared with the characteristic distance over which the magnetic field varies. Unlike many earlier treatments the transformations presented here preserve the axisymmetry of the dynamics when the magnetic field is axisymmetric. It is assumed that the magnetic field consists of a small nonaxisymmetric part plus the axisymmetric toroidal and poloidal parts. After the introduction of the magnetic moment adiabatic invariant the motion of the guiding center is studied. The results depend sensitively on the ratio of the poloidal magnetic field to the total magnetic field. In some cases a second adiabatic invariant exists and direct inferences concerning long time particle drifts are possible. In one case where a second adiabatic invariant fails to exist, long term drifts are studied by conventional perturbation expansions. At some points resonance or lack of resonance phenomena appear and determine the drift effects.
- Research Organization:
- New York Univ., NY (USA). Magneto-Fluid Dynamics Div.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76ER03077
- OSTI ID:
- 6631220
- Report Number(s):
- DOE/ER/03077-169; TRN: 81-004472
- Country of Publication:
- United States
- Language:
- English
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