A 1D1V Continuum Vlasov–Poisson Multipactor Analysis From Onset to Saturation Across the Entire First-Order Multipactor Regime

This report employs a Vlasov–Poisson model to elucidate fundamental electron phase–space mechanics of a multipactor discharge from onset to saturation. At the onset of multipactor, the electron phase–space is primarily defined by sharp features in both the physical space and energy space. With increasing electron density, space-charge effects lead to debunching of the swarm in phase–space. The temporal evolution of the electron energy distribution is studied across a single impact cycle. The average and peak-to-peak saturation values for the entire first-order multipactor regime are presented. Comparisons between the third- and fifth-order multipactors highlight the nuanced similarities and differences in the energy distribution of the multipacting system. The Vlasov–Poisson approach, which neglects collisions, is well suited for such analysis since the multipactor phenomenon occurs under near-vacuum collisionless conditions. It also overcomes difficulties associated with kinetic schemes that require adequately sampling all of the electron phase–space, including sparely populated regions, or special treatments to model strong growths in carrier densities.

I. Introduction

Electron multipaction leads to charge build-up within or around resonant radio frequency (RF) structures. These charge build-ups can degrade system performance and even damage mission-critical components. Thus, space and accelerator communities attempt to mitigate multipactor growth within RF devices. Mitigation techniques may include, but are not limited to, minimizing secondary electron yield (SEY) [1], [2], [3], [4], electron entrapment via corrugated or porous structures [5], [6], [7], [8], applied electromagnetic fields [9], and so on. Each type of multipactor suppression technique has its unique drawbacks, and thus, fabrication and testing of each suppression technique for a specific component can become costly and time-consuming. Space-based testing conditions can be notoriously difficult to replicate for an entire RF structure [10], [11]. These real-world limitations place added emphasis on accurate multipactor simulations to ensure the proper operation and a priori evaluation of the RF system.