Runaway electron flows in magnetized coaxial gas diodes

Abstract

Abstract This paper presents the experimental results on applying a strong magnetic field (B) to increase the uniformity and density of a picosecond runaway electron flow (RAEF) formed in an air coaxial diode with a tubular cathode. A uniform longitudinal field Bz allows to confine RAEF similarly to the electron beam in a magnetically insulated coaxial vacuum diode. Dependence of the spatial discreteness of RAEF emission and the transverse size of the emitting plasma regions on Bz has been demonstrated. For the cathode diameter of 8 mm, a current density was significantly increased from 40 A/cm2 (at Bz = const) to 100 A/cm2 by applying B-field with converging field lines. In the region of B maximum (5 T) the RAEF diameter was squeezed by ≈ 4 times.