Estimate of pre-thermal quench non-thermal electron density profile during Ar pellet shutdowns of low-density target plasmas in DIII-D
Artikel i vetenskaplig tidskrift, 2021

The radial density profile of pre-thermal quench (pre-TQ) early-time non-thermal (hot) electrons is estimated by combining electron cyclotron emission and soft x-ray data during the rapid shutdown of low-density (ne≲1019m−3) DIII-D target plasmas with cryogenic argon pellet injection. This technique is mostly limited in these experiments to the pre-TQ phase and quickly loses validity during the TQ. Two different cases are studied: a high (10 keV) temperature target and a low (4 keV) temperature target. The results indicate that early-time, low-energy (∼10 keV) hot electrons form ahead of the argon pellet as it enters the plasma, affecting the pellet ablation rate; it is hypothesized that this may be caused by rapid cross field transport of argon ions ahead of the pellet or by rapid cross field transport of hot electrons. Fokker-Planck modeling of the two shots suggests that the hot electron current is quite significant during the pre-TQ phase (up to 50% of the total current). Comparison between modeled pre-TQ hot electron current and post-TQ hot electron current inferred from avalanche theory suggests that hot electron current increases during the high-temperature target TQ but decreases during the low-temperature target TQ. The uncertainties in this estimate are large; however, if true, this suggests that TQ radial loss of hot electron current could be larger than previously estimated in DIII-D.


E M Hollmann

University of California

M. Austin

The University of Texas at Austin

I. Bykov

General Atomics

N. W. Eidietis

General Atomics

Ola Embréus

Chalmers, Fysik, Subatomär, högenergi- och plasmafysik

J. Herfindal

Oak Ridge National Laboratory

Mathias Hoppe

Subatomär, högenergi- och plasmafysik DP

A. Lvovskiy

General Atomics

P. Parks

General Atomics

C. Paz-Soldan

General Atomics

D. Shiraki

Oak Ridge National Laboratory

Ida Svenningsson

Chalmers, Fysik, Subatomär, högenergi- och plasmafysik

Physics of Plasmas

1070-664X (ISSN) 1089-7674 (eISSN)

Vol. 28 7 072501


Atom- och molekylfysik och optik

Fusion, plasma och rymdfysik

Den kondenserade materiens fysik



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