Space Charge Effects on Beam-Wave Interaction at the Output Gap of Vacuum Electron Tube

Electron beam-wave interaction is essential for particle acceleration, beam quality control, high-power electromagnetic radiation generation, and RF technologies development. In this research, we parametrically investigate the effects of space charge on beam-wave interaction using a vacuum electron tube for highly efficient RF power amplification, such as an inductive output tube (IOT) [1]. Studying space charge effects in the output gap of an IOT is necessary to improve the reliability and efficiency of electron beam systems, as space charge force is responsible for energy loss and instabilities.

The beam current and input impedance are investigated for different grid and anode potentials that affect the instantaneous current. We analyze the device parameters, including beam diameter, drift tube diameter, and disk thickness of the disk model of the IOT for large signals to measure device performance and the variation in space charge fields, gap fields, and normalized velocity through the beam interaction gap. We compare the simple and disk models with and without space charge to the experimental results, including the beam current, RF output power, electron efficiency, and gain (dB) in identifying the appropriate parameters [1,2].

References:

1. Carter, R.G., 2010. Simple model of an inductive output tube. IEEE transactions on electron devices, 57(3), pp.720-725

2. Orrett, J.F., Moss, A.J., Corlett, P., Buckley, S. and Rains, S.P., 2006. IOT testing at the ERLP. In Proc. EPAC 2006 (pp. 1382-84)