Measuring issues in the GEM detector system for fusion plasma imaging

Tomasz Czarski , M. Chernyshova , K. Malinowski (Instytut Fizyki Plazmy i Laserowej Mikrosyntezy) , Krzysztof Poźniak , Grzegorz Henryk Kasprowicz , Piotr Kolasiński , Rafał Krawczyk , Andrzej Wojeński , Paweł Linczuk , Wojciech Zabołotny , Axel Jardin , Dider Mazon , K. Jakubowska , G. Boutoux , F. Burgy , S. Hulin , D. Batani

Abstract

A measurement systems based on GEM (Gas Electron Multiplier) detectors is developed for X-ray diagnostics of tokamak plasmas. The multi-channel setup is designed for evaluation the X-ray source distribution in energy, space and time. The paper deals with the development of a fast analysis and elaboration of collected data, including charge cluster identification and the separation of coincided signals. The proposed algorithm can be applied iteratively for series of superimposed pulses. On-line separation of overlapped signals was implemented applying the FPGA (FPGA— Field-Programmable Gate Array) technology with relatively simple firmware processing. We demonstrate reconstruction of coinciding signals and retrieval of radiation source properties and energy spectra.