Evaluation of ambipolar potential barrier in the gas dynamic trap by Doppler spectroscopy

The recently developed Doppler spectroscopy diagnostic has been used to evaluate the height of ambipolar potential barrier forming in gas dynamic trap (GDT) plasma between central cell and region with a large magnetic expansion ratio beyond mirror. technique based on jet charge exchange target, allowed measure profile along line sight covering radial range from axis limiter. on-axis drop was found be $2.6 \div 3.1$ units plane electron temperature, which supports existing theoretical understanding suppression thermal conductivity GDT expander.