Theoretical design of the gun-cum-input cavity and focusing structure envisaged for a 350 MHz, 100 kW (CW) inductive output tube.

The paper reports the theoretical approach and computer-aided design results for a 350 MHz, 100 kW (CW) inductive output tube. The design considerations and methodologies employed for electromagnetic simulation of individual electron gun and RF cavity assemblies and that of their combined assembly were presented. The electron gun parameters namely the beam radius, perveance and electrodes dimensions were optimized. The input cavity was designed and the parameters, namely the resonant frequency, radius and length of the cavity with respect to the desired propagating mode were characterized. The combined integrated model demonstrates the RF input cavity placed onto the gun structure. The interaction of electron beam (40 kV, 3.5 A) and applied input RF signal of 400 W produces an RF current of ~ 85 A in the interaction gap (i.e. cathode-grid spacing). The focusing structure of the device necessary for getting the efficient amplification has also been designed and optimized. The simulations presented in the paper are carried out using CST, MAGIC2D and TRAK codes. [ABSTRACT FROM PUBLISHER]