Low-frequency whistler waves in quiescent runaway electron plasmas

Heidbrink, W. W.; Paz-Soldan, C.; Spong, D. A.; Du, X. D.; Thome, K. E.; Austin, M. E.; Lvovskiy, A.; Moyer, R. A.; Pinsker, R.; Van Zeeland, M. A.

Angol nyelvű Tudományos Szakcikk (Folyóiratcikk)
Megjelent: PLASMA PHYSICS AND CONTROLLED FUSION 0741-3335 1361-6587 61 (1) Paper: 014007 , 13 p. 2019
  • SJR Scopus - Condensed Matter Physics: D1
    In quiescent runaway electron plasmas in the DIII-D tokamak, whistler waves with frequencies between 90 and 200 MHz are driven unstable in plasmas with appreciable hard x-ray and nonthermal electron cyclotron emission (ECE). Narrow (delta f < 50 kHz) discrete modes with erratically spaced frequencies are observed. Unstable modes often extend over a range Delta f similar or equal to 50 MHz but lower frequency unstable modes are usually most intense. The dependency of the frequency on field and density implies a wavenumber k similar or equal to 150 m(-1) with parallel wavenumber k parallel to << k. Reducing the gap between the plasma and the wall increases the number of detected modes. Lowering the magnetic field promotes instability. Nonlinear limit-cycle-like oscillations in the whistler amplitude occur on a 10 ms timescale. The ECE signals often jump at whistler bursts, suggesting that the modes pitch-angle scatter the runaways. Sawteeth cause transient stabilization of the whistlers.
    Hivatkozás stílusok: IEEEACMAPAChicagoHarvardCSLMásolásNyomtatás
    2020-08-04 14:09