Diffusive instability of a Townsend discharge

Dependence of the transition from Townsend to glow discharge on secondary emission

In a recent paper Sijacic and Ebert have systematically studied the transition from Townsend to glow discharge, refering to older work from von Engel (1934) up to Raizer (1991), and they stated a strong dependendence on secondary emission $γ$ from the cathode. We here show that the earlier results of von Engel and Raizer on the small current expansion about the Townsend limit actually are the limit of small $γ$ of the new expression; and that for larger $γ$ the old and the new results vary by no more than a factor of 2. We discuss the $γ$-dependence of the transition which is rather strong for…

低驱动频率下介质阻挡放电的自脉冲特性

Self-pulsing of Dielectric Barrier Discharges at Low Driving Frequencies

本研究通过耦合一维氩等离子体流体模型与损耗介质等效RC电路，探究低驱动频率下介质阻挡放电的自脉冲特性，明确了pd值、介质特性、驱动频率对放电模式与电流脉冲的影响，发现铁电材料可放大放电电流。

Transition from Townsend to glow discharge: subcritical, mixed or supercritical

The full parameter space of the transition from Townsend to glow discharge is investigated numerically in one space dimension in the classical model: with electrons and positive ions drifting in the local electric field, impact ionization by electrons ($α$ process), secondary electron emission from the cathode ($γ$ process) and space charge effects. We also perform a systematic analytical small current expansion about the Townsend limit up to third order in the total current that fits our numerical data very well. Depending on $γ$ and system size pd, the transition from Townsend to glow discha…

A self-consistent hybrid model of kinetic striations in low-current Argon discharges

A self-consistent hybrid model of standing and moving striations was developed for low-current DC discharges in noble gases. We introduced the concept of surface diffusion in phase space described by a tensor diffusion in the nonlocal Fokker-Planck kinetic equation for electrons in the collisional plasma. Electrons diffuse along surfaces of constant total energy between energy jumps in inelastic collisions with atoms. Numerical solutions of the 1d1u kinetic equation for electrons were obtained by two methods and coupled to ion transport and Poisson solver. We studied the dynamics of striation …

A generalized Townsend's theory for Paschen curves in planar, cylindrical, and spherical geometries

In this work, we focus on plasma discharges produced between two electrodes with a high potential difference, resulting in the ionization of the neutral particles supporting a current in the gaseous medium. At low currents and low temperatures, this process can create luminescent emissions: the so-called glow and corona discharges. The parallel plate geometry used in Townsend's (1900) theory lets us develop a theoretical formalism, with explicit solutions for the critical voltage effectively reproducing experimental Paschen curves. However, most discharge processes occur in non-parallel plate …

Review of recent results on streamer discharges and discussion of their relevance for sprites and lightning

It is by now well understood that large sprite discharges at the low air densities of the mesosphere are physically similar to small streamer discharges in air at standard temperature and pressure. This similarity is based on Townsend scaling with air density. First the theoretical basis of Townsend scaling and a list of six possible corrections to scaling are discussed; then the experimental evidence for the similarity between streamers and sprites is reviewed. We then discuss how far present sprite and streamer theory has been developed, and we show how streamer experiments can be interprete…