Intense Gigawatt relativistic electron beam generation studies in planar and cylindrical Diodes

Abstract

Intense gigawatt relativistic electron beams (IREB) have found applications in the field of high-power microwave generation (HPM), free electron lasers, flash X-ray (FXR) generation, and surface modification etc. For all these applications, the intense electron beam is generated in field emission diode from the explosive emission cathode plasma. When the intense electron beam hits the anode, an anode plasma is produced. Space charge limited electron and ion emission occurs from these electrode plasmas. Movement of electrons, ions, electrode plasmas and the plasma uniformity controls various processes occurring in the high power vacuum diodes. Considerable experimental and theoretical work has been done in the study of beam generation processes but the information available is far from complete. An attempt has been made to understand the beam generation process under various diode configurations and also production of HPM from axial and coaxial virtual cathode oscillator using these beams. KALI 1000 and KALI 5000 (Kilo Ampere Linear Injector) pulse power system has been used to investigate the various aspects of IREB generation. KALI 5000 pulse power system has been operated without a prepulse switch to study the effect of prepulse generated plasma on IREB generation. The typical electron beam parameters studied were 200-450 keV, 10-40 kA, 100 ns with few hundreds of A/cm2 current density.