Behavior of a continuous uranium plasma stream expanding across a weak magnetic field

When an electron beam generates a uranium vapor in the electron beam evaporator, a uranium plasma is formed on the evaporating surface and expands. It was confirmed experimentally that this plasma could expand with increasing its drift velocity and that the plasma possessed a Boltzmann electron distribution along the streamline, even when it propagated across a magnetic field of 40-50 G. This behavior can be understood by the cross-field plasma expansion theory at 1/ε→0 limit, where ε is the dielectric constant of plasma [Phys. Fluids 25, 730(1982)]. The ion drift energy calculated from the measured polarization electric field is in good agreement with that estimated from the potential distribution and vapor drift energy, which confirms the ion acceleration along the plasma stream.