Thermionic Cooling of the Target Plasma to a Sub-eV Temperature

Abstract

Contemporary models of bounded plasmas assume that the target plasma electron temperature far exceeds the temperature of the cold electrons emitted from the target, T_emit. We show that when the sheath facing a collisional plasma becomes inverted, the target plasma electron temperature has to equal T_emit even if the upstream plasma is hotter by orders of magnitude. This extreme cooling effect can alter the plasma properties and the heat transmission to thermionically emitting surfaces in many applications. It also opens a possibility of using thermionic divertor plates to induce detachment in tokamaks.

5 pages, 4 figures, accepted version, manuscript was revised/improved based on referee reports

References in corpus (4)

• Charging and heat collection by a positively charged dust grain in a plasma
• Continuum Kinetic and Multi-Fluid Simulations of Classical Sheaths
• Investigation of the Short Argon Arc with Hot Anode, Part II: Analytical Model
• Floating potential of emitting surfaces in plasmas with respect to the space potential

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• On the role of secondary electron emission in capacitively coupled radio frequency plasma sheath: a theoretical ground
• An alternative simulation approach for surface flashover in vacuum using a 1D2V continuum and kinetic model
• Unveiling the role of dielectric trap states on capacitively coupled radio-frequency plasma discharge: dynamic charging behaviors