Non-linear modulation of short wavelength compressional Alfven eigenmodes

Journal Article · Mon Apr 15 00:00:00 EDT 2013 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4801663· OSTI ID:22130423

Fredrickson, E. D.; Gorelenkov, N. N.; Podesta, M.; Gerhardt, S. P.; Bell, R. E.; Diallo, A.; LeBlanc, B. ^[1]; Bortolon, A. ^[2]; Crocker, N. A. ^[3]; Levinton, F. M.; Yuh, H. ^[4]

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1. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2. University of California, Irvine, California 92697 (United States)
3. University of California, Los Angeles, California 90095 (United States)
4. Nova Photonics, Princeton, New Jersey 08543 (United States)

Most Alfvenic activity in the frequency range between toroidal Alfven eigenmodes and roughly one half of the ion cyclotron frequency on National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)], that is, approximately 0.3 MHz up to Almost-Equal-To 1.2 MHz, are modes propagating counter to the neutral beam ions. These have been modeled as Compressional and Global Alfven Eigenmodes (CAE and GAE) and are excited through a Doppler-shifted cyclotron resonance with the beam ions. There is also a class of co-propagating modes at higher frequency than the counter-propagating CAE and GAE. These modes have been identified as CAE, and are seen mostly in the company of a low frequency, n = 1 kink-like mode. In this paper, we present measurements of the spectrum of these high frequency CAE (hfCAE) and their mode structure. We compare those measurements to a simple model of CAE and present a predator-prey type model of the curious non-linear coupling of the hfCAE and the low frequency kink-like mode.

• OSTI ID: 22130423
• Journal Information: Physics of Plasmas, Vol. 20, Issue 4; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
APPROXIMATIONS
COMPARATIVE EVALUATIONS
CYCLOTRON FREQUENCY
CYCLOTRON RESONANCE
DOPPLER EFFECT
ION BEAMS
IONS
KINK INSTABILITY
MHZ RANGE 01-100
MODULATION
NONLINEAR PROBLEMS
PLASMA BEAM INJECTION
PLASMA CONFINEMENT
PLASMA DIAGNOSTICS
RF SYSTEMS
SPHERICAL CONFIGURATION
TOKAMAK DEVICES
WAVELENGTHS