In experimental studies of the startup plasma in the end system of the AMBA
L-M device, it is found that a longitudinal electron current of similar to
1 kA flows along the plasma stream during the plasma-source discharge. The
radial profiles of the current density in several cross sections are measur
ed by a movable magnetic probe. Near the plasma source, the current density
profile is annular in shape, which is related to the geometry of the disch
arge channel; as the distance from the source increases, the inner part of
the plasma stream is gradually filled with the current.