Abstract Details
Abstracts
Author: Emma G. Devin
Requested Type: Poster
Submitted: 2025-03-12 15:52:04
Co-authors: V. N. Duarte
Contact Info:
Princeton Plasma Physics Laboratory
100 Stellarator Rd
Princeton, NJ 08540
USA
Abstract Text:
The nonlinear theory of discrete driven kinetic instabilities in the presence of collisions and background dissipation has been analytically studied in two limiting cases, either near (e.g., [1,2,3,4]) or far from (e.g., [5,6]) the excitation threshold. In this work, we examine the system at arbitrary marginality in canonically conjugated action and angle variables for the case of Krook collisions, avoiding the need to expand the distribution in powers of a small parameter. We find solutions for the wave amplitude and distribution function at steady saturation, or dynamically in the limit where the effective collision rate is much larger than the linear growth rate less the background damping rate, where the distribution function depends on time only through the evolution of the amplitude [3,4]. The solutions recover previously known forms and saturation levels in both near and far from marginal stability limits and reveal general features of the underlying dynamics. We formally show that the saturation amplitude is always proportional to the square of the effective collisionality, and in the regime where the distribution function depends on time only through the evolution of the amplitude, we find that the saturation is intrinsically stable. The results are also compared with numerical simulations of the wave amplitude evolution.
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3. Duarte, V. N., et al. Phys. Plasmas 26, (2019).
4. Duarte, V. N. & Gorelenkov, N. N. Nucl. Fusion 59, (2019).
5. Petviashvili, N. PhD thesis, UT Austin (1999).
6. Berk, H. L. & Breizman, B. N. Phys. Fluids B 2, (1990).
Characterization: 1.0
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