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

Nuclear Fushion

article

A. Maffini¹  L. Moser²  L. Marot²  R. Steiner²  D. Dellasega¹  A. Uccello³  E. Meyer²  M. Passoni¹ 

[1] Department of Energy;Department of Physics, University of Basel;Istituto di Fisica del Plasma ‘P. Caldirola’

关键词: first mirror;    ITER;    plasma cleaning;    laser cleaning;    optical plasma diagnostics;    rhodium;    reflectance;   

DOI  :  10.1088/1741-4326/aa5d05

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

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, suitablein situcleaning 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.

【 授权许可】

Unknown