Hard X-Ray Collimation System at the T-15MD Tokamak

Abstract

The Hard X-Ray collimation system was installed at the T-15MD tokamak (major radius of R = 1.48 m, minor radius of a = 0.67 m, elongation of k = 1.7–1.9, triangularity of δ = 0.3–0.4, toroidal magnetic field of B_T = 2 T, plasma current of up to I_p = 2 MA, and discharge duration of up to 30 s) to provide the possibility of measuring the spatial and temporal evolution of runaway electron beams. The diagnostic is based on LaBr₃(Ce) scintillation detectors, witch provides energy spectrum measurements for energies form 0.3 to 10 MeV. Monte Carlo simulation of the shielding efficiency in the GEANT4 environment showed that the collimator provides 2° field of view (FOV). Horizontal and vertical FOV movement along the plasma cross-section is arranged by a rotating base and screw support elements. An algorithm for processing the signals from the scintillation detectors with a graphical user interface and data visualization is used for reconstruction of the spectra. The results of testing the detector in a laboratory setup and in preliminary experiments carried out with the T-15MD tokamak in which runaway electrons beams were generated are presented.