Non-resonant multipactor—A statistical model

Abstract

High power microwave systems operating in vacuum or near vacuum run the risk of multipactor breakdown. In order to avoid multipactor, it is necessary to make theoretical predictions of critical parameter combinations. These treatments are generally based on the assumption of electrons moving in resonance with the electric field while traversing the gap between critical surfaces.Through comparison with experiments, it has been found that only for small system dimensions will the resonant approach give correct predictions. Apparently, the resonance is destroyed due to the statistical spread in electron emission velocity, and for a more valid description it is necessary to resort to rather complicated statistical treatments of the electron population, and extensive simulations. However, in the limit where resonance is completely destroyed it is possible to use a much simpler treatment, here called non-resonant theory. In this paper we develop the formalism for this theory, use it to calculate universal curves for the existence of multipactor, and compare with previous results. Two important effects that leads to an increase in the multipactor threshold in comparison with the resonant prediction are identified. These are the statistical spread of impact speed, which leads to a lower average electron impact speed, and the impact of electrons in phase regions where the secondary electrons are immediately reabsorbed, leading to an effective removal of electrons from the discharge.

Analysis of two‐dimensional multipactor model for ferrite circulator junction

“…With the rapid development of computer technology, computer-aided modeling and computer-aided analysis have become an important part of engineering design due to their irreplaceable advantages. Driven by computer technology, multipactor simulation models [16][17][18][19][20][21][22] have appeared. And Particle-in-Cell (PIC) algorithm 23,24 and Monte Carlo algorithm 25,26 have been widely used in multipactor discharge simulation.…”

A numerical and theoretical study of the multipactor appearance in the presence of a DC parallel electric field

“…The resonance theory is based on the strong assumption that all electrons follow the same trajectory; it was shown to be unreasonable when the gap is too big or when the dispersion in emission velocities is too wide. 33,39 In this study, the waveguide is extremely tight, which should not invalid the theory. The main difference between the simplistic and the more realistic configurations is that we included emission velocities dispersion in the latter.…”

Multipactor breakdown in microwave pulses

“…(v e + v ω ) 2 ω/(2π) [11], where Δv e is the average spread in the emission velocity v e and v ω is the electron oscillatory velocity in the microwave field. When this criterion is fulfilled, the resonant zones can be found by considering three different effects.…”

“…First of all, electrons participating in a classical resonant discharge must cross the gap in an odd number of field half cycles. The electron trajectories are determined by the solution of the equation of motion for the electrons and given by [11]…”

“…The physical parameters are W 1 = 50 eV, W e = 3 eV, and σ max = 3. The dashed straight line represents the breakdown voltage predicted by Eq (11).…”