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Necessity of development of (1) in-situ tritium detection technique

9th ITPA meeting on SOL/divertor physics, Garching, May 7-10, 2007. Application of optical techniques for in situ surface analysis of carbon based materials T. Tanabe, Kyushu University. Necessity of development of (1) in-situ tritium detection technique

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Necessity of development of (1) in-situ tritium detection technique

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  1. 9th ITPA meeting on SOL/divertor physics, Garching, May 7-10, 2007 Application of optical techniques for in situ surface analysis of carbon based materialsT. Tanabe, Kyushu University Necessity of development of (1) in-situ tritium detection technique To determined where and how much tritium is retained at particular locations in tokamak (2) in-situ removing technique Different techniques will be required depending on tritium retaining materials and its concentration

  2. Optical techniques can be in-situ surface analysis systems with assistance of optical fibers, mirrors and lens • UV to Visible Optical absorption/emission spectroscopy • Infrared to far-infrared IR, FT-IR, Raman • Laser light Optical emission/absorption Energy loss (Laser Raman) Neutral particle emission (Thermal Desorption Spectrosocpy) Ion emission (TOF-MASS) Electron energy loss or electron emission spectroscopy can be used but require sophisticated energy analyzing systems in vacuum

  3. In this work, Application of • UV to Visible Optical absorption/emission spectroscopy • Infrared to far-infrared IR, FT-IR, Raman for carbon materials retaining hydrogen. Lots of works have been done for thin films (a:C-H film) but not much for bulk carbon materials, because graphite is a conductor and opaque. Need to analyze reflecting light, which gives limited information of near surface region.

  4. In-situ high resolution observation & diffraction Initial B ^ c 1300s B // c 5 nm 002 000 300s 1900s HOPG Fiber

  5. Intensity [a.u.] HOPG 1400 1200 1100 1800 1600 Raman Shift (cm-1) Laser Raman Spectra of Hydrogen ion irradiated HOPG h hs s B // c Electron diffraction

  6. D+ ion irradiation Amorphous Homogenous in 3D 3D modification Defect formation between the layers 2D modification Defect production in the layers Original Graphite layers K. Niwase et al., J. Nucl. Mater. 191-194 (1992) 335-339

  7. He+ irradiation D+ ion irradiation Amorphous Amorphous K. Niwase et al., J. Nucl. Mater. 191-194 (1992) 335-339

  8. inboard JT-60: Open divertor tiles Re-deposited layer Eroded area

  9. Line analysis

  10. Crystalline size [ nm ] 4.4 2.9 1.8 2.2 439.0 8.8 TEXTORALT-ｌｌ　tile ○Redepositedarea ○Eroded area

  11. 10mm Irradiation with very high flux and high temperature at NAGDIS-II Cooperation with Drs. Ohno and Takamura 1200K Irradiation 7.7×1026 /m-2 Eroded Deposited 700K Irradiation 3.4×1026 /m-2 Mostly eroded

  12. Crystalline size [ nm ] 450 9.0 4.5 3.0 2.0 600～700K (25keV) Amorphous Ion implantation 25keV 1200K Deposited area FWHM1580cm-1 1200K Eroded area 700 K (100eV) Unirradiated I1355/I1580

  13. Optical absorption and band gap of a:C-H film CH stretch band IR region Wider band gap Higher sp3 C Absorption coeff. of three a:C-H film with different refractive index. Absorption edge of diamond is shown for comparison G. Compagnini, Phys. Rev. B51(1995)11168 B. Disher, et al. Appl. Phys.Lett. 42(1983)636

  14. Ion irradiated carbon fiber (VGCF) FT-IR spectra in the CH stretch band region Estimated relative CHx density in the hydrogen-ion implanted VGCF with or without the post-irradiation heat-treatment, as a function of the heat-treatment temperature FT-IR spectra in the CH stretch band region of the VGCF after successive irradiations of 6.0, 3.0 and 1.0 keV H+ ions to saturation. (a) 373 K, (b) 623 K, (c) 823 K, (d) 923 K. The separated-band assignment, band frequency are indicated at the resolved bands.

  15. C-H Stretching 1015 ion/cm2 1017 ion/cm2 1018 ion/cm2 Gap widening ※ Reference: HOPG FT-IR Spectra of hydrogen implanted HOPG in reflection geometry Standing wave Polarized light Reflected light Sample

  16. ConclusionsFollowing techniques are probed to be useful forin situ surface analysis of carbon materials • Laser induced optical emission Need to understand ablation physics • Laser Raman Spectroscopy determines micro-structure but hard to get H/C. • Optical absorption Spectroscopy Band gap width could be related to H/C. • FT-IR could give H/C but sill need to increase S/N.

  17. Laser induced visible light emission SAR266 Emission from C2, C, C+ & C2+ WAR266 Emission from C2 Y. Sakawa et al. J. Nucl. Mater. in press

  18. Laser induced Time Of Flight Mass Spectrometry (TOFMS) SAR266 Emission of C+ , C2+ ions WAR266 Carbon clusters (Cn+) Y. Sakawa et al. J. Nucl. Mater in press

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