Effects of Magnetic Focusing on Power and Stability of VE Amplifiers

TL;DR

This paper presents a theoretical analysis of how magnetic focusing influences the stability, gain, and power of VE amplifiers, introducing new models for beam envelope behavior and optimizing focusing conditions for enhanced performance.

Contribution

It introduces a novel solution to the beam envelope equation that accounts for large oscillations and demonstrates how magnetic focusing can significantly improve VE amplifier gain and power.

Findings

Optimized magnetic focusing conditions increase RF amplifier gain.

New beam envelope model accounts for large oscillations.

Significant power enhancement in Ka-band structures.

Abstract

Theory and modeling of new discovered effects of the oscillating e-beam boundary formed in a magnetic focusing channel on the stability, gain, and power of VE amplifiers are presented. The RF structure and e-beam circuit parameters are computed for different beam envelope radii and oscillation amplitudes and then the self-excitation thresholds are obtained from the Determinant equations. A new solution of the beam envelope equation not limited by the small-amplitude oscillations is derived and used to determine the magnetic focusing conditions providing various beam envelope radii and oscillation amplitudes. It is shown for the example Ka-band serpentine structure that the optimum radius as well as axial position of the oscillating beam envelope allow achieving significantly greater gain and power of RF amplifiers.