Interpretation of runaway electron synchrotron and bremsstrahlung images
Journal article, 2018

The crescent spot shape observed in DIII-D runaway electron synchrotron radiation images is shown to result from the high degree of anisotropy in the emitted radiation, the finite spectral range of the camera and the distribution of runaways. The finite spectral camera range is found to be particularly important, as the radiation from the high-field side can be stronger by a factor 106than the radiation from the low-field side in DIII-D. By combining a kinetic model of the runaway dynamics with a synthetic synchrotron diagnostic we see that physical processes not described by the kinetic model (such as radial transport) are likely to be limiting the energy of the runaways. We show that a population of runaways with lower dominant energies and larger pitch-angles than those predicted by the kinetic model provide a better match to the synchrotron measurements. Using a new synthetic bremsstrahlung diagnostic we also simulate the view of the gamma ray imager diagnostic used at DIII-D to resolve the spatial distribution of runaway-generated bremsstrahlung.

synchrotron radiation

synchrotron image



synthetic diagnostic

runaway electron


Mathias Hoppe

Chalmers, Physics, Subatomic and Plasma Physics

Ola Embréus

Chalmers, Physics, Subatomic and Plasma Physics

C. Paz-Soldan

General Atomics

R. A. Moyer

University of California

Tünde Fülöp

Chalmers, Physics, Subatomic and Plasma Physics

Nuclear Fusion

0029-5515 (ISSN)

Vol. 58 8 082001

Driving Forces

Sustainable development

Areas of Advance



Basic sciences

Subject Categories

Fusion, Plasma and Space Physics



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