Effect of emission velocity spread of secondary electrons in two-sided multipactor

Abstract

Detailed numerical simulations of the two-sided multipactor have been carried out within a plane-parallel model. The main aim of the simulations is to clarify the uncertainty that still exists in the literature concerning the overlapping of multipactor zones. Three different codes (Monte Carlo, particle-in-cell, and statistical) were used to calculate the multipactor charts within a wide range of parameters such as spread of initial velocities of the secondary electrons and maximum value of the secondary emission yield. It was found that an increase in the spread of initial velocities results in overlapping of the multipactor zones, provided the secondary emission is high enough. In the opposite case, an increase in the spread of initial velocities leads to a suppression of the higher multipactor zones.

Non-resonant multipactor—A statistical model

“…It is more difficult to compare our results with Sazontov et al 17 , for they do not state explicitly at what fraction v ω /v 1 the limiting values for the SEY were found. It is also difficult to compare with the values of Kossyi et al 28 and Sakamoto et al 33 , for in the first case there is the presence of a DC field to account for, and in the second case, the model for secondary emission is rather different.…”

“…In this example, the emission velocity is assumed to follow a normal (Gaussian) distribution, with a standard deviation ∆v 2 e = 0.025v d . According to (17), this value of emission velocity spread implies that the non-resonant regime should be reached when dω/(2πv d ) > 40, but it is clear from the figure that the mixing of the consecutive electron bunches becomes significant far before this.…”

“…For complicated structures this process becomes extremely complex. For this reason, the statistical approach has so far only been applied to double-sided multipactor between parallel plates [15][16][17][18] , in a rectangular waveguide 19 , and single-sided multipactor on a dielectric surface 20 . The theory has also recently been generalized to multicarrier signals, again in the parallel plates geometry 21 .…”

Long-term multipactor discharge in multicarrier systems

“…On the other hand, the spread of the emission energy of the secondary emitted electrons is taken into account in both the analytical and the numerical analyses, since it results also in a spread in the electron impacting energy and, therefore, an increase in the range of valid phases at the end of the OFF interval. 13 This presumably enhances the probability of the electron to participate in the multipactor process of the consecutive ON interval.…”

Simulations of multipactor in circular waveguides

“…This type of discharge is an undesirable phenomenon in many practical microwave applications and the intense study of this phenomenon during the last decades has mainly been stimulated by the necessity to be able to accurately predict the multipactor threshold in different microwave subsystems. [1][2][3][4][5] These studies have resulted in development of various numerical tools capable of simulating multipactor in different geometries including parallel plates, 6,7 coaxial cables, [8][9][10] dielectric windows, [11][12][13] rectangular and wedge-shaped waveguides, [14][15][16] microstrip lines, 17 waveguide irises, [18][19][20] and rf filters and transformers. [21][22][23] A notable exception is multipactor breakdown in circular waveguides, which has been given scant interest, in spite of its technical importance.…”