FILAMENTARY DOUBLE-LAYERS

The properties of double layers produced in current filaments' have be en studied. The experiments were performed in a magnetized triple plas ma device in which the diameter of the central plasma column could be varied. The scaling of the double layer potential drop V(dl), with the parameter jd2, where j is the current density in the double layer and d is the double layer thickness, was determined for several values of the current filament radius R0. For relatively large values of R0, th e one-dimensional (Langmuir) scaling was obeyed, V(dl) approximately ( jd2)2/3. When R0 was decreased, a departure from the strictly one-dime nsional scaling was observed, with V(dl), becoming less and less depen dent on the parameter jd2.