Postmortem assessment of the WEST Fiber Bragg grating and thermocouple diagnostic performances with HADES

J. Gaspar (1) , Y. Corre (2) , Y. Anquetin (1) , J-L. Gardarein (1) , C. Pocheau (2) , H. Roche (2) , N. Vignal (2) , A. Bureau (2) , Romain Cotillard (3) , M. Houry (2) , Guillaume Laffont (3) , T. Loarer (2) , M. Missirlian (2) , P. Reilhac (2) , E. Tsitrone (2)

1 IUSTI - Institut universitaire des systèmes thermiques industriels
2 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
3 LCFO (CEA, LIST) - Laboratoire Capteurs Fibres Optiques (CEA, LIST)

Plasma facing components temperature measurement is required to ensure safe high power for long pulse tokamak operation and for physics studies. During the WEST phase 1, a set of 20 thermocouples (TC) and 4 fibers Bragg grating (FBG) have been exposed to five experimental campaigns with 3889 plasmas for a total plasma duration of about 7h15 and 21.2 GJ of cumulated injected energy. This paper presents the performances in terms of response time and high temperature sustaining assess with high heat flux tests performed in the HADES facility. The response time of the TC remains at the same level as before their installation in the divertor. However, the FBG have shown clear increase of their response time depending on the location due to a degradation of the thermal contact of the graphite adhesive and the FBG or component. Finally, one regenerated FBG has been exposed to high temperature, showing that absolute temperature measurement is found reliable up to 1100 °C with the start of some spectrum degradations. Full erasure of the grating is obtained after 10 s at 1200 °C well above the stable temperature of 900 °C of the regenerated FBG.

Mots clés: instrumentation; Optical Fiber Sensor; Fiber Bragg Grating; Distributed and Quasi-distributed sensing; temperature measurement; tokamak; WEST; plasma; HADES facility; divertor

Domaines: Physique des plasmas [physics.plasm-ph]; Instrumentations et Détecteurs [physics.ins-det]; Optique / photonique

J. Gaspar, Y. Corre, Y. Anquetin, J-L. Gardarein, C. Pocheau, et al.. Postmortem assessment of the WEST Fiber Bragg grating and thermocouple diagnostic performances with HADES. Fusion Engineering and Design, 2023, 190, pp.113525. ⟨10.1016/j.fusengdes.2023.113525⟩. ⟨cea-04087261⟩