Experimental demonstration of improving resonant-multipactor threshold by three-dimensional wavy surface

Abstract

A proof-of-principle experiment is presented demonstrating the suppression of multipactor breakdown in a coaxial multipactor device with three-dimensional periodic wavy surfaces. By changing the power and pulse width of the microwave source, threshold behavior near breakdown was obtained for this wavy-surface structure and a smooth-surface structure used for comparison. With a wide pulse width at a suitable power, the coefficient of reflection for the smooth-surface structure was found to increase, whereas the coefficient of transmission decreased. For the wavy-surface structure, a similar behavior appeared, only when the microwave pulse had a width of order of a few seconds. Accompanied by changes in transmission power characteristics, distinct increases in the second and third harmonic components were evident for the smooth-surface structure. These experimental results demonstrate that the wavy-surface structure effectively suppresses multipactor breakdown with the suppression increasing with the pulse width.

Two-Phase-Interfaced, Graded-Permittivity Titania Electrical Insulation by Atmospheric Pressure Plasmas

“…Although the electric field strength increases near the interface between the anatase and rutile phases of the TiO 2 coatings, it does not significantly affect the surface flashover voltage. The possible reason may be that the initiation of surface flashover in vacuum is generally caused by the HV electrode . At the micrometer level, the porous features on the surfaces in two-phase titania may impede the transfer of electric charge across the surface, while microcraters may affect electron hopping. , As a result, the electron multipactor effect along the insulator surface is reduced.…”

“…The possible reason may be that the initiation of surface flashover in vacuum is generally caused by the HV electrode. 5 At the micrometer level, the porous features on the surfaces in two-phase titania may impede the transfer of electric charge across the surface, while microcraters may affect electron hopping. 57,58 As a result, the electron multipactor effect along the insulator surface is reduced.…”

“…Recently, with the increase of the voltage level and capacity of electrical equipment (e.g., in power transmission grids or pulsed power devices, etc. ), the electrical insulation often fails when high electric fields are generated. , For example, once the surface flashover (the discharge phenomenon along a solid insulator surface as shown in Figure S1) occurs in power transmission lines, with currents up to ∼kA, the electrical equipment may burst into flames or explode by overheat, which is hazardous and detrimental to power system safety. , …”

“…), the electrical insulation often fails when high electric fields are generated. 4,5 For example, once the surface flashover (the discharge phenomenon along a solid insulator surface as shown in Figure S1) occurs in power transmission lines, with currents up to ∼kA, the electrical equipment may burst into flames or explode by overheat, which is hazardous and detrimental to power system safety. 6,7 Therefore, solid insulation materials with high surfaceinsulating performances (high flashover threshold voltage) are pursued over the last half a century.…”

Comparative analysis of single-surface multipactor discharges at different microwave frequencies

“…Several researchers carried out experiments on dielectric multipactor discharges at microwave frequencies of 2-11 GHz. [8][9][10][11] They measured the luminescence intensity, multipactor threshold, and absorption and reflection of microwave power by discharge plasma. In 2019, Schaub et al conducted dielectric multipactor experiments at 110 GHz and found that the dielectric multipactor threshold increases approximately linearly with the frequency when the microwave electric field is parallel to the dielectric surface.…”