Experimental Investigations of a Streaming Plasma Column at Low Magnetic Fields

An experimental study of a low β surface-ionized streaming plasma column is presented for low magnetic fields. As the magnetic field is lowered to 400 G a hollow plasma column sets in and edge oscillations are suppressed. At 175 G a distinct hollow cellular pattern is observed by plasma camera photographs. Below 100 G a hollow plasma column with larger inner and outer diameters reappears. These lower magnetic field phenomena result in an order of magnitude increase in the plasma density. The large increase in density was always accompanied by a change in the ionizer sheath conditions, from ion to electron, as the magnetic field was lowered below 400 G.