Movable magnetic probe system in the T-10 tokamak.

New magnetic probe system is installed on the T-10 tokamak to investigate fast-scale magnetic perturbations (f up to 2 MHz). The system is based on vertical and horizontal magnetic probes made by nickel wire in glass enamel isolation (effective area 20-250 cm(2)) separated from the support structures by ceramic spacers (5-10 mm). The probe system is mounted on the top of movable rode allowing positioning along vertical axis close to the plasma boundary at the low field side of the torus. Additional positioning system allows rotation of the probes around the vertical axis on pulse-to-pulse basis. The probes are directly connected to the analog-to-digital converter (ADC) module (acquisition rate 60 MHz) through short (~4 m) coaxial cables. The system allowed identification of the fast-scale magnetic oscillations (0.2-0.5 MHz) during energy quench phase of the disruption instability in plasma with high density. Amplitude of the fast-scale magnetic oscillations decays with distance from the plasma boundary 2-10 times faster than one of the standard magnetohydrodynamic modes.