Articolo in rivista, 2013, ENG, 10.1007/s10894-012-9568-7

Plasma radiofrequency discharges as cleaning technique for the removal of C-W coatings

Cremona; E. Vassallo; R. Caniello; F. Ghezzi; G. Grosso; L. Laguardia

Istituto di Fisica del Plasma (IFP), EURATOM-ENEA-CNR Association, Via Cozzi 53, 20125 Milan, Italy 2012

Erosion of materials by chemical and physical sputtering is one of the most concern of plasma wall interaction in tokamaks. In divertor ITER-like tokamaks, where carbon and tungsten are planned to be used, hydrogenated C-W mixed compounds are expected to form by erosion, transport and re-deposition processes. The selection of these materials as divertor components involves lifetime and safety issues due to tritium retention in carbon co-deposits. In this paper a cleaning technique based on RF (13.56 MHz) capacitively coupled H2/Ar plasmas has been used to remove C-W mixed materials from test specimens. The dependence of the removal rate on the H2/Ar ratio and on the plasma pressure has been investigated by X-ray photoelectron spectroscopy, atomic force microscopy, profilometry as regards the solid phase and by Langmuir probe and optical emission spectroscopy as regards the plasma phase. The best result has been obtained with a H2/Ar ratio of 10/90 at a pressure of 1 Pa. An explanation based on a synergistic effect between physical sputtering due to energetic ions and chemical etching due to radicals, together with the pressure dependence of the ion energy distribution function, is given.

Journal of fusion energy (Dordr., Online)

Keywords

C-W mixed materials, Film removal, Erosion rate, RF capacitively coupled plasmas

CNR authors

Laguardia Laura, Caniello Roberto, Vassallo Espedito, Grosso Giovanni Maria, Ghezzi Francesco Mauro, Cremona Anna

CNR institutes

IFP – Istituto di fisica del plasma "Piero Caldirola"

ID: 213606

Year: 2013

Type: Articolo in rivista

Creation: 2013-05-15 10:48:45.000

Last update: 2021-04-10 11:12:41.000

External IDs

CNR OAI-PMH: oai:it.cnr:prodotti:213606

DOI: 10.1007/s10894-012-9568-7

ISI Web of Science (WOS): 000317973500002

Scopus: 2-s2.0-84877792261