Stochastic orbit loss of neutral beam ions from NSTX due to toroidal Alfvén eigenmode avalanches

Journal Article · Mon Dec 17 00:00:00 EST 2012 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/53/1/013009· OSTI ID:1170962

Darrow, D. S. ^[1]; Crocker, N. ^[2]; Fredrickson, E. D. ^[1]; Gorelenkov, N. N. ^[1]; Gorelenkova, M. ^[1]; Kubota, S. ^[2]; Medley, S. S. ^[1]; Podestà, M. ^[1]; Shi, L. ^[1]; White, R. B. ^[1]

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1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Univ. of California, Los Angeles, CA (United States). Dept. of Physics

Short toroidal Alfvén eigenmode (TAE) avalanche bursts in the National Spherical Torus Experiment (NSTX) cause a drop in the neutron rate and could also cause a loss of neutral beam ions at or near the full injection energy over an extended range of pitch angles. The simultaneous loss of wide ranges of pitch angle suggests stochastic transport of the beam ions takes place. When beam ion orbits are followed with a guiding centre code that incorporates the plasma's magnetic equilibrium plus the measured modes, the predicted ranges of lost pitch angle are like those seen in the experiment, with distinct populations of trapped and passing orbits lost. These correspond to domains where the stochasticity extends in the orbit phase space from the region of beam ion deposition to the loss boundary and the trajectories along which modes may transport particles extend from the deposition volume to the loss boundary.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Univ. of California, Los Angeles, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: DE-ACO2-09CH11466; DE-FG02-99ER54527
• OSTI ID: 1170962
• Journal Information: Nuclear Fusion, Vol. 53, Issue 1; ISSN 0029-5515
• Publisher: IOP Science
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Plasma Physics