Plasma diffusion in a space-simulation beam-plasma discharge

Electron density and temperature profiles have been measured in a large-facility beam-plasma-discharge(V sub B = 1.3 KeV, I sub B = 63 ma) at low pressure (P = 2-4(10 to the -6th power)Torr) and low magnetic fields (B = 1.2 G). The results follow an exponential behavior and are found to be in good agreement with a simple diffusion model. The favorable comparison between theory and experiment yields the first estimate of cross-field electron diffusion (perpendicular diffusion coefficient(nom) = 2.2 million sq cm/sec) under conditions intended to simulate Spacelab-borne beam-plasma investigations. This value for perpendicular diffusion coefficient is orders of magnitude larger than would be expected for a cross-field collisional diffusion process, a result which is identified with the turbulent state of collective beam-plasma interactions.