Suppressing and initiation of multipactor discharge on a dielectric by an external dc bias

O A Ivanov,A L Vikharev,M A Lobaev,V A Isaev

doi:10.1103/physrevstab.13.022004

O A Ivanov, A L Vikharev + Show 2 more

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https://doi.org/10.1103/physrevstab.13.022004

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Abstract

The results of studying experimentally the influence of an external dc electric field on the multipactor threshold on the surface of a dielectric (quartz) are presented. In the experiments, a high-$Q$-factor microwave resonator was excited at the ${\mathrm{TE}}_{012}$ mode in the 3-cm wavelength band. The dependence of the breakdown threshold on the value and direction of the electrostatic field is determined. It is found that the external dc field repulsing the electrons from the dielectric surface increases the threshold significantly, whereas the field attracting the electrons decreases it. It is shown that one can manage the multipactor efficiently, namely suppress or initiate it, by changing the direction and intensity of the dc field.

Highlights

The term ‘‘multipactor discharge’’ means a specific form of the discharge occurring in vacuum near a dielectric or metal surface under the effect of a high-frequency electromagnetic field [1]
The first category includes the methods allowing one to decrease the energy and secondary emission of electrons. Such methods include changing the geometry of the waveguide system in order to reduce high-frequency fields on the dielectric surface [4,5] or modifying the dielectric surface by using special corrugations [6] or depositing films with low secondary electron emission yields on it [7,8,9]
The most common theoretical models of the multipactor [14,15] employ the approximation of a homogenous rf electric field, which is parallel to the dielectric surface, and assume that there is an external static field driving the electrons back to the surface

Summary

Introduction

The term ‘‘multipactor discharge’’ means a specific form of the discharge occurring in vacuum near a dielectric or metal surface under the effect of a high-frequency electromagnetic field [1]. In the experimental conditions, the electric field En, which was normal to the dielectric surface, was determined by the superposition of the external dc field Ez and the axial component of effective field Ez $ rzjEsj2 [Eq (1)] formed by the gradient of the rf potential, En 1⁄4 Ez Æ Ez. In the experiment, we used polished quartz disks having the surface roughness Ra 1⁄4 0:1 m and three different thicknesses, namely, d1 1⁄4 2:3 mm, d2 1⁄4 4:2 mm, and d3 1⁄4 6 mm.

Results

Conclusion