Effect of partially ionized impurities and radiation on the effective critical electric field for runaway generation
Journal article, 2018

We derive a formula for the effective critical electric field for runaway generation and decay that accounts for the presence of partially ionized impurities in combination with synchrotron and bremsstrahlung radiation losses. We show that the effective critical field is drastically larger than the classical Connor-Hastie field, and even exceeds the value obtained by replacing the free electron density by the total electron density (including both free and bound electrons). Using a kinetic equation solver with an inductive electric field, we show that the runaway current decay after an impurity injection is expected to be linear in time and proportional to the effective critical electric field in highly inductive tokamak devices. This is relevant for the efficacy of mitigation strategies for runaway electrons since it reduces the required amount of injected impurities to achieve a certain current decay rate.

runaway electron

Fokker-Planck

disruption

tokamak

Author

Linnea Hesslow

Chalmers, Physics, Subatomic and Plasma Physics

Ola Embréus

Chalmers, Physics, Subatomic and Plasma Physics

George Wilkie

Chalmers, Physics, Subatomic and Plasma Physics

Gergely Papp

Max Planck Institute

Tünde Fülöp

Chalmers, Physics, Subatomic and Plasma Physics

Plasma Physics and Controlled Fusion

0741-3335 (ISSN) 1361-6587 (eISSN)

Vol. 60 7 074010

Implementation of activities described in the Roadmap to Fusion during Horizon 2020 through a Joint programme of the members of the EUROfusion consortium (EUROfusion)

European Commission (EC), 2014-01-01 -- 2019-01-01.

Running away and radiating (PLASMA)

European Commission (Horizon 2020), 2015-10-01 -- 2020-09-30.

Subject Categories

Accelerator Physics and Instrumentation

Fusion, Plasma and Space Physics

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1088/1361-6587/aac33e

More information

Latest update

7/3/2018 8