Investigation of electron-runaway in the slow toroidal  -Z pinch, LT1

An investigation, based on the measurement of thick target bremsstrahlung, has been made of the runaway electrons in LT1. The method different from those usually employed for the detection of the presence of runaway electrons in two respects. Firstly, a target was inserted into the plasma to sample the electrons at various plasma radii and, secondly, the X-ray detection equipment was calibrated in terms of the energy of the electrons producing the radiation rather than in terms of the energy of the radiation itself. The experimental results indicated that the runaway occurred mainly at a plasma radius of about 4 cm as would be expected from the radial variation in electron density and temperature. The energy distribution was obtained for electrons striking the target and estimates made of the average runaway rate.