LIBS application in Joint European Torus

A. Semerok (1) , D. L'Hermite (1) , J-M. Weulersse (1) , J-L. Lacour (1) , C. Grisolia (2) , M. Kempenaars (3) , N. Bekris (4)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
3 CCFE - Culham Centre for Fusion Energy
4 JET-EFDA - Joint European Torus

We present here the results on the first successful application of LIBS for remote in situ diagnostics of PFC in Joint European Torus (JET), the biggest European tokamak (operating with D/T mixture, Be-chamber walls). LIBS in situ application in JET has required a thorough preliminary optimisation and careful adjustment of LIBS interaction parameters, and both optical and detection systems to satisfy the following conditions 10-meter remote measurements; limited apertures of optical windows and mirrors; high vacuum; tritium and Be environments; a very low repetition rate laser; non-accessible interaction zone; limited time for LIBS experiments authorised by JET. LIBS feasibility was demonstrated with JET EDGE LIDAR laser system (a Ruby laser, 3 Joules/pulse, 690 nm wavelength, 300 ps pulse duration, up to 70 GW/cm2 intensity, 1 shot per 5 minutes). A number of analytical spectral lines of D/T, C II, Cr I, W I and Be II in 400-670 nm spectral range were identified. With the increase in the number of the laser shots applied onto a divertor zone (a DL on tungsten-substrate), the spectral line intensities of D/T and from impurities (Cr I, Be II) were decreasing, while the W-spectral lines were appearing in the spectrum. The obtained results and some principal considerations on laser and spectrometer parameters for LIBS in situ application in the modern thermonuclear installations (JET, WEST, ITER), and also particular features of tritium cartography will be presented and discussed.

Mots clés: Tritium retention; LIBS in situ analysis; ITER.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]; Physique Nucléaire Théorique [nucl-th]

A. Semerok, D. L'Hermite, J-M. Weulersse, J-L. Lacour, C. Grisolia, et al.. LIBS application in Joint European Torus. EMSLIBS’2015 - 8th euro-mediterranean symposium on laser-induced breakdown spectroscopy 2015, Sep 2015, Linz, Austria. ⟨cea-02489571⟩