A Alpha Particle Driven Alfven Wave Instability in a Tandem Mirror Reactor.
Abstract
Because their energies greatly exceed the plug potential, fusion reaction alpha particles in a tandem mirror reactor will be mirror confined rather than electrostatically confined by the end plugs. Hence, the alpha particle distribution function will have a loss cone. This anisotrophy in the distribution function is shown to destabilize Alfven waves in the central section of a tandem mirror reactor. The wave equation with a modified cold plasma response is used to determine the radial mode structure and real frequency of the Alfven waves in cylindrical geometry. The growth rate is calculated from the resonant particle part of the plasma response. Destabilization of the wave occurs due to a cyclotron resonance of the alpha particles. The resonant interaction of the wave with the alpha particles will pitch -angle scatter the alphas into the loss cone, effectively widening the loss cone. In a typical fusion plasma (central ion temperature T(,io) = 20 keV, central electron temperature T(,eo) = 20 keV, central beta (beta)(,c) = 0.4, vacuum magnetic field B(,V) = 3T) we find 60% of the alpha particle energy is lost when the effects of the instability are included, whereas only 17% is lost without the instability.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1982
- Bibcode:
- 1982PhDT.......116H
- Keywords:
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- Physics: Fluid and Plasma