Flow of Low-Density High-Speed Plasma through a Magnetic Barrier

The barrier transmission ratio I/I0 of a stream of plasma can be evaluated from theory in terms of the temperatures and masses of the ions and electrons, the speed of the stream, and the ratio ΔB/B0 of the height ΔB of the barrier field above the guiding field B0. All of these parameters were measured for a hydrogen plasma except the ion temperature Ti. Johnson-Malter double-probe data yielded at the maximum density point of the stream a plasma speed of 1.3 × 107 cm sec−1, a number density of 5 × 1013 cm−3, and an electron temperature T̃e = 3.5 ± 0.2 ev for B0 = 780 gauss at the position of the barrier. I/I0 decreased to 0.5 for ΔB/B0 = 17.8 at which point a theoretical curve has been fitted with T̃i = 7.1 ev; this value for T̃i was confirmed by application of the equipartition theory of Spitzer to the observed change of electron temperature with time.