Dynamics of runaway electrons in magnetized plasmas
The evolution of a runaway electron tail driven by a subcritical dc electric field in a magnetized plasma is studied numerically using a quasi-linear numerical code (2-D in v- and k-space) based on the Ritz-Galerkin method and finite elements. Three different regimes in the evolution of the runaway tail depending on the strength of the dc electric field and the ratio of plasma to gyrofrequency, were found. The tail can be (a) stable and the electrons are accelerated to large parallel velocities, (b) unstable to the Cerenkov resonance due to the formation of a positive slope on the runaway tail, (c) unstable to the anomalous Doppler resonance instability driven by the large velocity anisotropy in the tail. Once an instability is triggered (Cerenkov or anomalous Doppler resonance) the tail relaxes into an isotropic distribution resulting in less acceleration. The synchrotron emission of the runaway electrons shows large enhancement in the radiation level at the high-frequency end of the spectrum during the pitch-angle scattering of the fast particles. The results are relevant to recent experimental data from the Princeton Large Torus (PLT) during current-drive experiments and to the microwave bursts observed during solar flares.
- Research Organization:
- Maryland Univ., College Park (USA)
- OSTI ID:
- 5299827
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
PLASMA
RUNAWAY ELECTRONS
DYNAMICS
DIRECT CURRENT
ELECTRIC FIELDS
PLT DEVICES
SOLAR FLARES
SYNCHROTRON RADIATION
BREMSSTRAHLUNG
CURRENTS
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
MECHANICS
RADIATIONS
SOLAR ACTIVITY
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700103* - Fusion Energy- Plasma Research- Kinetics
640104 - Astrophysics & Cosmology- Solar Phenomena