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In situ cleaning of diagnostic first mirrors: an experimental comparison between plasma and laser cleaning in ITER-relevant conditions

Maffini, A. and Moser, L. and Marot, L. and Steiner, R. and Dellasega, D. and Uccello, A. and Meyer, E. and Passoni, M.. (2017) In situ cleaning of diagnostic first mirrors: an experimental comparison between plasma and laser cleaning in ITER-relevant conditions. Nuclear Fusion, 57 (4). 046014.

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Abstract

This paper presents an experimental comparison between the plasma cleaning and the laser cleaning techniques of diagnostic first mirrors (FMs). The re-deposition of contaminants sputtered from a tokamak first wall onto FMs could dramatically decrease their reflectance in an unacceptable way for the proper functioning of plasma diagnostic systems. Therefore, suitable in situ cleaning solutions will be required to recover the FMs reflectance in ITER. Currently, plasma cleaning and laser cleaning are considered the most promising solutions. In this work, a set of ITER-like rhodium mirrors contaminated with materials tailored to reproduce tokamak redeposits is employed to experimentally compare plasma and laser cleaning against different criteria (reflectance recovery, mirror integrity, time requirement). We show that the two techniques present different complementary features that can be exploited for the cleaning of ITER FMs. In particular, plasma cleaning ensures an excellent reflectance recovery in the case of compact contaminants, while laser cleaning is faster, gentler, and more effective in the case of porous contaminant. In addition, we demonstrate the potential benefits of a synergistic solution which combines plasma and laser cleaning to exploit the best features of each technique.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Nanomechanik (Meyer)
UniBasel Contributors:Meyer, Ernst
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:IOP Publishing
ISSN:0029-5515
e-ISSN:1741-4326
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:15 Jan 2018 14:52
Deposited On:15 Jan 2018 14:52

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