Particle in cell simulation of vacuum tube devices

Particle in Cell (PIC) simulation techniques plays a very important role in the design of all the vacuum tube devices especially operating in the microwave region. These simulation techniques reduce the time and resources needed for the device development. The advancement in the simulation techniques has led to a better matching of operating microwave frequencies and microwave generation efficiency of a working microwave device. A range of microwave devices can be designed with the PIC simulations. Specifically, we have simulated relativistic backward wave oscillators (RBWO) and relativistic magnetrons (RM) for microwave generation. The simulation model for RBWO involves design of explosive electron emission (EEE) diodes for intense relativistic electron beam (IREB) generation, slow wave structure (SWS) for electron beam-microwave interaction in backward wave mode and design of electron beam dump. The S-band and X-band frequency RBWO devices have been developed and tested for Gigawatt level output microwave power. RM are crossed field devices and are widely used for microwave generation in S-band frequency. EEE cathode characteristics have been simulated under the influence of crossed fields.RM with diffraction output has been simulated with 0.34 T magnetic field. The output frequency is 2.52 GHz and this magnetron is tested at 20 MW microwave power with 2.54 GHz. (author)