Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Berk-Breizman Model as a Paradigm for Energetic Particle-driven
  Alfven Eigenmodes   The achievement of sustained nuclear fusion in magnetically confined plasma
relies on efficient confinement of high-energy ions produced by the fusion
reaction. Such particles can excite Alfven Eigenmodes (AEs), which
significantly degrade their confinement and threatens the vacuum vessel of
future reactors. To develop diagnostics and control schemes, a better
understanding of linear and nonlinear features of resonant interactions between
plasma waves and high-energy particles, is required. In the case of an isolated
single resonance, the problem is homothetic to the so-called Berk-Breizman (BB)
problem, which is an extension of the classic bump-on-tail electrostatic
problem, including external damping to a thermal plasma, and collisions. A
semi-Lagrangian simulation code, COBBLES, is developed to solve the
initial-value BB problem. The nonlinear behavior of instabilities in
experimentally-relevant conditions is categorized into steady-state, periodic,
chaotic, and frequency-sweeping (chirping) regimes. The chaotic regime is shown
to extend into a linearly stable region, and a mechanism for such subcritical
instabilities is proposed. Analytic and semi-empirical laws for nonlinear
chirping characteristics, such as sweeping-rate, lifetime, and asymmetry, are
developed and validated. Long-time simulations demonstrate the existence of a
quasi-periodic chirping regime. Collisional drag and diffusion are shown to be
essential to reproduce the alternation between major chirping events and
quiescent phases, which is observed in experiments. Based on these findings, a
fitting procedure between COBBLES simulations and chirping AE experiments is
developped. This procedure, which yields local linear drive and external
damping rate, is applied to Toroidicity-induced AEs (TAEs) on JT-60U and MAST
tokamaks. This suggests the existence of TAEs relatively far from marginal
stability.

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The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
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The categories of this paper are: stat
0
The categories of this paper are: hep-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg