Electron Gun Thermal Depended Properties’ Analysis of a High-Power ${W}$ -Band Sheet Beam Extended Oscillator

The studies of thermal-dependent properties, including the high-efficiency heater, thermal deformation of the cathode and focusing electrode (FE), and the associated beamforming problems of a sheet beam gun (SBG) for a
${W}$
-band sheet beam extended interaction oscillator (W-SBEIO), are presented. A simple but efficient method is proposed to complete the 3-D thermal simulations of SBG, including the contact thermal resistance. The heater efficiency is greatly improved by a three-layer folded cathode supporter. Almost 50% reduction in heating power (31.6–15.9W) is achieved at 1100 °C cathode temperature. The corresponding test was conducted on the optimized structure, and the experiment results validated its effectiveness. Besides, the axial thermal expansion is decreased by 38.9% and 47% for the cathode and the FE separately. The sheet beamforming deterioration caused by thermal deformation is studied by 3-D simulations. The prepositioning of cathode and bias potential of FE is applied to keep ideal beamforming with a 45-kV 2-A and 6.8 mm
$\times0.36$
mm sheet beam.