Identification of the small-scale x-ray perturbations during magnetic reconnection in the T-10 tokamak plasma

Analysis of the magnetic reconnection is one of the key elements in studies of the fast evolution of magnetic structures in variety of astrophysics phenomena and laboratory plasmas. In high temperature collisionless plasma magnetic reconnection can be facilitated by small-scale magnetic perturbations generated inside the reconnection layer around X-points of the magnetic islands. Present paper considers possible mechanisms of the small-scale plasma perturbations and represents detailed description of the diagnostic techniques used for identification of the perturbations in the T- 10 tokamak (R=1.5m, a=0.3m). The small-scale plasma perturbations are identified in the T-10 tokamak using Si surface barrier detectors with enhanced spatial and temporal resolution (dr~3-5mm, and dt~ 300 ns, accordingly), 3D X-ray tomographic arrays based on multi-wire gas detectors, AXUV detectors, and fast magnetic probe placed at the movable rod positioned close to the plasma surface. Simultaneous measurements of the nonthermal electrons (20-200keV) generated during the reconnection are provided by 2D CdTe tomographic arrays (10 vertical and 6 horizontal detectors), Ge PHA spectrometer, and miniature in-vessel X-ray spectrometer based on CdTe detector with movable 2D Soller collimators. Initial experiments have indicated generation of the small- scale X-ray perturbations in frequency range 150-300 kHz during fast stage of the magnetic reconnection during sawtooth collapse. The perturbations appear as bursts at multiple frequencies, which can indicate possible role of the nonlinear interaction of the MHD modes. Another type of the high-frequency perturbations (~300 kHz) are observed during minor disruptions in plasma with relatively low density. Perturbations in the case are accompanied by bursts of the nonthermal X-ray radiation, which can indicate possible connection of the perturbations with the nonthermal electrons.