Simulations of multipactor thresholds in shielded microstrip lines

Abstract

A particular software ‘MuSLi’ has been developed and applied for simulations of the multipactor effect in shielded microstrip lines with cross-sections that are partially filled with dielectric material. The software combines an electromagnetic field solver, determining the electric field structure in the microstrip line, and a Monte Carlo algorithm, calculating the corresponding electron trajectories taking into account a spread of the electron initial velocity and different secondary emission properties of the metal and dielectric surfaces. The simulations were carried out for a number of structures of interest for communication systems, currently being discussed for application in coming space missions. The microstrip line system is shown to be strongly resistant to multipactor growth and the main reason for this is identified as the ponderomotive (or Miller) force, which governs the average electron motion in non-uniform rf fields and which tends to push the electrons out of regions with strong rf fields.

Multipactor Breakdown in Elliptical Waveguide Carrying Orthogonal Polarizations

“…Accordingly, the proposed analysis concerns with use of the elliptical waveguides as an iris, as reported in [20,21]. Silver is used in the computations of the secondary electrons, which is characterized by the following SEY (δ) parameters (extracted from [6]): first crossover energy, W 1 = 30 eV; maximum value of SEY, δ max = 2.22; and incident electron energy for δ max , W max = 165 eV.…”

“…The procedure used in this work is based on the concept of the effective electron in context of a Monte-Carlo algorithm, which has been successfully used in technical literature for dealing with this kind of problems, as reported in [17,20,21,23].…”

“…Thus, a number of microwave structures have been studied during last years in the technical literature. In these studies, the effective electron method has been used to obtain the RF breakdown threshold for several components including rectangular waveguides [15], coaxial transmission lines [16,17], circular waveguides [18,19], microstrip lines [20], wedge-shaped rectangular guides [21,22], elliptical waveguides [23,24], and dielectric resonator waveguide filters [25]. The details of this technique have been extensively reported in [14] and [22], which basically includes the simultaneous tracking of the finite number of effective electrons trajectories.…”

Simulations of multipactor in circular waveguides

“…Previously the same problem was met in simulations of the multipactor in rectangular waveguides 14 and microstrip lines. 17 As emphasized in these papers, Monte Carlo simulations of the long time evolution of the multipactor discharge must be very accurate and in order to suppress statistical fluctuations it is necessary to consider a very large number of electron trajectories. The necessary number of trajectories increases rapidly with increasing duration of the simulated multipactor evolution and this makes the simulations very time consuming.…”

“…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.…”