Abstract Details
Abstracts
Author: Elena V Belova
Requested Type: Poster
Submitted: 2019-02-22 19:16:05
Co-authors: M. Yamada, N. Barbour
Contact Info:
PPPL
MS 18, PPPL, PO Box 451
Princeton, NJ 08543
United States
Abstract Text:
Numerical study of particle confinement in FRC has been performed for a representative prolate field-reversed configuration with small kinetic parameter S* < 10. Dependence on mirror ratio, device size, and the applied perturbation amplitude and frequency has been investigated. Full orbit particle simulations using the HYM code demonstrate that significant fraction (up to a half) of confined ions for typical experimental FRC conditions are mirror-trapped, and thus experience losses due to non-adiabaticity. Ion confinement is investigated in the presence of a set of the small amplitude global MHD modes, and its dependence on perturbation amplitudes, the excited mode numbers, and the energy of the fast ions is analyzed. Simulations show that even a single unstable mode can lead to large losses of FRC-confined ions depending on mode frequency and amplitude. The resonant particles satisfy condition: nωt− ω = kωb, where ωt and ωb are toroidal and axial bounce frequencies, and k=±1,3,5… for tilt-like mode polarization. FRC-confined-ion losses increase dramatically in cases when higher-order resonances overlap, which leads to depletion of particles in the region of overlap. Mirror-confined ions show much weaker interaction with the mode due to mode localization inside the separatrix, and stochasticity of particle orbits. Even for a relatively large amplitude δV~0.1VA, perturbation induced losses are comparable with non-adiabatic losses of mirror-trapped ions.
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