Development of Nuclear Radiation Based Tomography Methods for Runaway Electrons in Fusion Plasmas: First Results and Prospects

The study of Runaway Electron (RE) physics and their response to mitigation strategies is crucial to safeguard ITER structural integrity. During their motion REs collide with background ions before hitting the inner vessel of the machine and thus they emit Bremsstrahlung photons in the gamma range of the spectrum. It is possible to detect such radiation using a LaBr3(Ce) spectrometer with counting rate capability in the MHz range and high energy resolution [1][5]. The measured spectra contain information about the RE energy distribution, which can be reconstructed using specific inversion (or econvolution) algorithms. The deconvolution operation is computationally faster than first principles simulations and its use in RE studies might be many fold: it can be used to improve synthetic diagnostic calculations or as a preliminary method for RE spectra analysis.