Conference paper · Journal article
Comparison of unfolding methods for the inference of runaway electron energy distribution from 𝜸-ray spectroscopic measurements
UniversitĂ degli Studi di Milano-Bicocca1
National Research Council of Italy2
Uppsala University3
RAS - Ioffe Physico Technical Institute4
Department of Physics, Technical University of Denmark5
Plasma Physics and Fusion Energy, Department of Physics, Technical University of Denmark6
the Eurofusion MST1 Team7
ASDEX Upgrade Team8
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 χ2 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.
Language: | English |
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Publisher: | IOP Publishing |
Year: | 2021 |
Pages: | C12005 |
Proceedings: | 4<sup>th </sup>European Conference on Plasma Diagnostics |
ISSN: | 17480221 |
Types: | Conference paper and Journal article |
DOI: | 10.1088/1748-0221/16/12/C12005 |
ORCIDs: | Salewski, M. |
Analysis and statistical methods Nuclear instruments and methods for hot plasma diagnostics Plasma diagnostics - interferometry, spectroscopy and imaging Plasma diagnostics- charged-particle spectroscopy