A step towards the diagnostic of the ITER first wall: in-situ LIBS measurements in the WEST tokamak

As part of the development of proven diagnostics allowing the characterization of ITER's PFUs (Plasma Facing Units) without dismantling, LIBS (Laser-Induced Breakdown Spectroscopy) is a serious candidate for determining the multi-elemental composition. In this article, we report a measurement campaign carried out within the WEST tokamak using an original device based on the following technological choices. (1) The laser source and the spectrometer are placed outside the tokamak. (2) The laser pulses are conveyed by an optical fiber. (3) The signals are collected by a second optical fiber. (4) The optical focusing and collection device is placed in the desired location by a remote handling arm (AIA, Articulated Inspection Arm). The processed signals allow the measurement of the composition of the irradiated material. The technological choices are discussed in the light of their implementation and proposals are made for a more efficient future version of the system.