RAPID CURRENT TRANSITION IN A CROSSED-FIELD DIODE

The transmitted current in a crossed-field gap has been characterized analytically by a number of authors. Using a one dimensional PIC simul ation, we explore the behavior of the crossed-field diode at B=B-Hull. For mono-energetic (cold) emission, a rapid reduction of transmitted current is observed when the injected current exceeds the critical cur rent by just 1%. The addition of a small electron temperature normal t o the cathode eliminates the transition, even for kT/V similar to 10(- 5) (V=10 kV, gap = 1 cm, B=337 G, J=1.69 A/cm(2)), while an isotropic velocity distribution accelerates the transition. (C) 1996 American In stitute of Physics.