Electric discharge

About: Electric discharge is a research topic. Over the lifetime, 13085 publications have been published within this topic receiving 123096 citations. The topic is also known as: discharge.

The corona discharge, its properties and specific uses

Abstract: The main properties of corona discharges are reviewed, with emphasis on the features which make them unique for use as non-equilibrium chemical reactors : Their stability and ease of operation over a wide range of gases and pressures, including atmospheric ; their sharply confined ionization regions where hot electrons interact with cold gas, inducing reactions without back reactions ; and their extended low field drift regions which act as gaseous electrolytes, inducing electrochemical reactions on surfaces. Present and future applications are discussed : Synthesis of ozone and ammonia, promotion of flames and combustion, surface treatment, and electrical insulation improvement.

Fluid simulations of glow discharges: Effect of metastable atoms in argon

Abstract: A one‐dimensional fluid simulation of a 13.56 MHz argon glow discharge including metastable species was performed as an example of a coupled glow‐discharge/neutral‐transport‐reaction system. Due to the slow response time of metastables (∼10 ms) direct time integration of the coupled system requires ∼105 rf cycles to converge. This translates to prohibitively long computation time. An ‘‘acceleration’’ scheme was employed using the Newton–Raphson method to speed up convergence, thereby reducing the computation time by orders of magnitude. For a pressure of 1 Torr, metastables were found to play a major role in the discharge despite the fact that their mole fraction was less than 10−5. In particular, metastable (two‐step) ionization was the main mechanism for electron production to sustain the discharge. Bulk electric field and electron energy were lower, and a smaller fraction of power was dissipated in the bulk plasma when compared to the case without metastables. These results suggest that neutral transport and reaction must be considered in a self‐consistent manner in glow discharge simulations, even in noble gas discharges.

Densification mechanisms in spark plasma sintering of nanocrystalline ceramics

Abstract: Effect of the particle size on the possible electric discharge during the SPS was examined. Nanoparticle compacts enable accumulation of high electric charge, and discharge under conventional voltages used for the SPS. The critical particle size for the electric discharge is both morphological and material dependent. The early stages of densification of the nanocrystalline powder compact proceed either by the plastic deformation or grain-rotation coalescence and sliding, aided by softening of the particle surfaces. The active densification mechanism depends on the changes both in the mechanical and electrical properties with temperature. Densification of 11 nm nc-MgO particles with low yield stress proceeds by plastic deformation already at 700 °C. However, densification of 34 nm nc-YAG particles with high yield stress proceeds by nano-grain rotation aided by particle surface softening. Densification at the final stages of SPS is associated with diffusional processes, where curvature driven grain growth predominates.