In a world increasingly facing new challenges at the forefront of plasma scientific research and technological innovation, CNR and ISTP pledge progress and achieve an impact in the integration of research into societal practices and policy

Comparison of unfolding methods for the inference of runaway electron energy distribution from gamma-ray spectroscopic measurements

Panontin E.; Dal Molin A.; Nocente M.; Croci G.; Eriksson J.; Giacomelli L.; Gorini G.; Iliasova M.; Khilkevitch E.; Muraro A.; Rigamonti D.; Salewski M.; Scionti J.; Shevelev A.; Tardocchi M.

Unfolding techniques are employed to reconstruct the 1D energy distribution of runaway electrons from Bremsstrahlung hard X-ray spectrum emitted during plasma disruptions in tokamaks. Here we compare four inversion methods: truncated singular value decomposition, which is a linear algebra technique, maximum likelihood expectation maximization, which is an iterative method, and Tikhonov regularization applied to 2 and Poisson statistics, which are two minimization approaches. The reconstruction fidelity and the capability of estimating cumulative statistics, such as the mean and maximum energy, have been assessed on both synthetic and experimental spectra. The effect of measurements limitations, such as the low energy cut and few number of counts, on the final reconstruction has also been studied. We find that the iterative method performs best as it better describes the statistics of the experimental data and is more robust to noise in the recorded spectrum.

ID 463196
DOI 10.1088/1748-0221/16/12/C12005
PRODUCT TYPE Journal Article
LAST UPDATE 2022-11-18T11:42:58Z