Four Models of Electron Distribution in the Orbitron

Abstract

As a guide to the design of orbitron pumps and gauges, the radial variation of electron number density is calculated for four models of angular and axial momentum distributions. Uniform angular momentum distribution (for fixed axial momentum) gives an almost constant density. Angular momentum distribution that varies as sin2 gives two peaks. Adding a uniform distribution of axial momentum decreases the density near the cathode such that the outer peak is removed from the two-peak model. Also, the density is approximately proportional to the electron speed near the cathode in the model with uniform distribution of angular momentum.