Simulation of the Output Stage of Picosecond Multi-Gigawatt Electron Accelerator

We presented the results of numerical simulation of the output path of a picosecond electron accelerator based on a solid-state generator with a peak power of 100 GW and an output pulse duration of 100 ps and an IMA3-150E vacuum diode. The simulation is conducted in time domain and is based on vector potential form of Maxwell’s equations coupled to a nonlinear lumped element governed by Child-Langmuir law to describe the interaction of the travelling wave with the electron beam current. Particular attention is paid to pulse distortions on path discontinuities, as well as distortions associated with energy losses in the line conductors and in the transformer oil filling the line. A time-domain model of dielectric losses in transformer oil is presented based on experimental data. The simulation results include the calculation of optimal parameters of the conical transition between the generator and the diode, simulated time-domain reflectometry analysis of the vacuum diode, evaluation of the influence of path discontinuities on pulse distortion, and an estimation of the parameters of the electron beam, which amounted to: maximum energy of 2.6 MeV, current of 21 kA, current pulse duration of 115 ps.