Analysis of multipactor in a rectangular waveguide using Spark3D software

What is it about?

Multipactor is a resonant nonlinear electron multiplication effect that may occur in high power microwave devices at very low pressures, such as those operating in particle accelerators and satellite subsystems. It is caused by multiple secondary electron emissions due to repeated (multiple) electron impact onto material surfaces. This phenomenon has been known to cause vacuum window failure, generation of excessive noise in communication satellites, detuning resonant cavities, and an increase in surface outgassing that could lead to a more destructive plasma discharge. Thus, multipactor research has been a topic of continued interest. In this study, multipactor in a rectangular waveguide was analyzed using numerical simulation software "Spark3D". We observed that there are cases where the impact electron energy decreases despite an increase in power due to growing non-resonance of the microwave field and electron oscillations. As a consequence, it was uncovered that when the average Secondary Emission Yield (SEY) in the highest field region is close to or less than one, multipactor may be caused in a lower field region where the SEY is effectively higher than one.

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Photo by Lavi Perchik on Unsplash

Photo by Lavi Perchik on Unsplash

Why is it important?

We observed from experiment and simulation that there are cases where the impact electron energy decreases despite an increase in power due to growing non-resonance of the microwave field and electron oscillations, resulting in not only two threshold points where secondary emission yield (SEY)=1 but several more. As a consequence, it was uncovered that when the average Secondary Emission Yield (SEY) in the highest field region is close to or less than one, multipactor may be caused in a lower field region where the SEY is effectively higher than one.

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