Measurement of the diffusion lifetime of a plasma in Tokamak-3 by the neutral hydrogen injection method

Abstract

A description is given of experiments with the pulsed injection of a neutral gas during discharge in Tokamak-3 The electron concentration was measured by a method of multichord probing with 2 mm waves. The flow of neutral gas from the chamber walls and from the diaphragm was determined from measurements of the intensity of the hydrogen spectral line in three directions. The diffusion lifetime in the experiments described is in the range 20-30 ms and the halt in the reduction of the electron concentration observed in the intermediate discharge stage is not associated with an increase in the flow of neutral gas but with an improvement in the plasma confinement. The flows from the diaphragm and from the chamber walls are compared, as are the diffusion and energy life times.