Anomalous erosion of an insulator under the action of a stream of plasma

A clearly defined periodic structure aligned parallel to the channel axis (Fig. 1) has been observed to occur under the action of the plasma stream in plasma Hall accelerators subjected to extended tests. These photographs of the eroded surfaces are distinctly different from the usual images of surfaces subject to ion bombardment, and theories which deals with some of this behavior have been put forth in Ref 5. In Fig.1, there is noted a rough marcrostructure aligned not perpendicular but rather parallel to the ion flow. This structure appears to have a period in the millimeter range. It was concluded that in the region where the insulator undergoes intense bombardment by a quasineutral beam in the presence of E and H fields, a new and previously unreported type of erosion is observed in the insulator, with this erosion thought to be brought about by electrons