TY - JOUR
T1 - Role of Kinetic Instability in Runaway-Electron Avalanches and Elevated Critical Electric Fields
AU - Liu, Chang
AU - Hirvijoki, Eero
AU - Fu, Guo Yong
AU - Brennan, Dylan P.
AU - Bhattacharjee, Amitava
AU - Paz-Soldan, Carlos
N1 - Publisher Copyright:
© 2018 American Physical Society.
PY - 2018/6/28
Y1 - 2018/6/28
N2 - The effects of kinetic whistler wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from experiments at the DIII-D National Fusion Facility, we show that RE scattering from excited whistler waves can explain several poorly understood experimental results. We find an enhancement of the RE avalanche for low density and high electric field, but for high density and low electric field the scattering can suppress the avalanche and raise the threshold electric field, bringing the present model much closer to observations. The excitation of kinetic instabilities and the scattering of resonant electrons are calculated self-consistently using a quasilinear model and local approximation. We also explain the observed fast growth of electron cyclotron emission signals and excitation of very low-frequency whistler modes observed in the quiescent RE experiments at DIII-D tokamak. Simulations using ITER parameters show that by controlling the background thermal plasma density and temperature, the plasma waves can also be excited spontaneously in tokamak disruptions and the avalanche generation of runaway electrons may be suppressed.
AB - The effects of kinetic whistler wave instabilities on the runaway-electron (RE) avalanche is investigated. With parameters from experiments at the DIII-D National Fusion Facility, we show that RE scattering from excited whistler waves can explain several poorly understood experimental results. We find an enhancement of the RE avalanche for low density and high electric field, but for high density and low electric field the scattering can suppress the avalanche and raise the threshold electric field, bringing the present model much closer to observations. The excitation of kinetic instabilities and the scattering of resonant electrons are calculated self-consistently using a quasilinear model and local approximation. We also explain the observed fast growth of electron cyclotron emission signals and excitation of very low-frequency whistler modes observed in the quiescent RE experiments at DIII-D tokamak. Simulations using ITER parameters show that by controlling the background thermal plasma density and temperature, the plasma waves can also be excited spontaneously in tokamak disruptions and the avalanche generation of runaway electrons may be suppressed.
UR - http://www.scopus.com/inward/record.url?scp=85049380392&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85049380392&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.120.265001
DO - 10.1103/PhysRevLett.120.265001
M3 - Article
C2 - 30004735
AN - SCOPUS:85049380392
SN - 0031-9007
VL - 120
JO - Physical review letters
JF - Physical review letters
IS - 26
M1 - 265001
ER -