Plasma and Fusion Research

Volume 16, 1405107 (2021)

Regular Articles

On the Field Focusing Effect at the Tungsten Fuzzy Nanostructures Formed by Helium Plasmas
Katsuaki TANABE
Department of Chemical Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan
(Received 10 September 2021 / Accepted 12 November 2021 / Published 20 December 2021)

Abstract

Tungsten fuzzy nanostructures commonly form on the plasma-facing walls of magnetic-confinement nuclear fusion reactors, induced by the helium plasma irradiation. We calculate the field enhancement factors at the fuzz tips of tungsten, molybdenum, and tantalum, quantitatively representing the degree of field focusing, based on the classical electromagnetic field theory under the quasistatic approximation, for a model system comprising a subwavelength-scale prolate metal hemispheroid protruding from a conducting plane. Field enhancement factors of 2.4 × 103, 5.4 × 106, and 2.3 × 1010 for the spheroidal aspect ratio of 10, 100, and 1000, respectively, are observed in the gigahertz regime for the incident electric field parallel to the fuzz, i.e., normal to the reactor wall. Such a potential large field focusing effect may be worth accounting for in the designing and operation of fusion reactors.

Keywords

nuclear fusion reactor, plasma-facing wall, electromagnetic field, field enhancement, metal, nanoparticle, fuzzy nanostructure

DOI: 10.1585/pfr.16.1405107

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