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1 – Experience of diagnostics used for LH grill protection

Report on the Diagnostics - WG4 (A Ekedahl, O Tudisco ). 1 – Experience of diagnostics used for LH grill protection 2 – Layout of the suitable diagnostics in ITER 3 – Info on fibre optics for wave guide arc detection. IR camera for detecting arcs in Tore Supra.

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1 – Experience of diagnostics used for LH grill protection

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  1. Report on the Diagnostics - WG4 (A Ekedahl, O Tudisco) 1 – Experience of diagnostics used for LH grill protection 2 – Layout of the suitable diagnostics in ITER 3 – Info on fibre optics for wave guide arc detection

  2. IR camera for detecting arcs in Tore Supra Choc 34100 : PC3 = 1.7MW, PC2 = 1.1MW, t = 52.7s The IR system works, but is really too slow (20 ms) to be efficient.

  3. Test of Ha-system for LH launcher security in Tore Supra Refl. Coeff Ha grill Ha-signal responds more rapidly to arc than IR measurements and UV-spectroscopy of impurities. IR grill Cu A. Ekedahl, CH/NTT-2001.004 (2001) Fe

  4. 1 2 3 4 5 Bolometry for LH launcher security in JET Vertical bolometry, Octant 3 nl PLH Fe15 Fe23 LH launcher, Octant 3 Bolo2 Bolo4 Bolo24 RT M. Goniche et al., to be presented at 18th Topical Conf. on RF Power in Plasmas, Gent (2009) The difference Bolo2-Bolo4 gives reliable detection of arcs in front of the grill mouth.

  5. IR and VIS in parallel in all lines of sight (Presentation O. Tudisco, 1 April 2009)

  6. Info on VIS / IR system Port space: Horizontal ports: 1, 3, 9 and 12 to view the outer wall. Top ports: 2, 5, 8, 11, 14 and 17 to view the inner wall. LH launcher port: 11 Time resolution: Standard: 10ms time resolution. In addition: defined zones that have up to 20 ms time resolution.  Need to find out the localisation of these fast zones.  If no suitable zones, specify the need for this in the LH system design. How to distinguish an arc from ELMs: R. Reichle proposes to use also a camera in a top port, viewing the inner wall in front of the LH grill, as a complementary system to the camera in the horizontal port. The idea is that an arc in front of the LH grill can create a reflection on the inner wall. If an arc feature is seen on the horizontal camera viewing the grill and on the top camera viewing the inner wall simultaneously, then there is likelihood of an arc.

  7. Info on Bolometry Port space: No details from R. Reichle (RO) on this yet (but info exists in PID).  If no suitable lines of sight for LH, R.R. (RO) could try to influence this choise. Time resolution: Bolometry is a slow measurement that needs to be integrated over ~200 ms. However, an intelligent acquisition system should be able to pick up large, rapid variations and treat them as abnormal events. Experience from JET: The vertical bolometry camera, situated above the LH launcher in Octant 3, has been used for LH launcher security since 2000.  Reliable measurement, but which could be optimised further.

  8. Project Integration Document (PID), Version 3.0, Jan 2007, Editor: J. How Port allocation for diagnostics Upper ports: Vis / IR (inner wall?): 2, 5, 8, 11, 14, 17 Ha spect (outer edge): 2 Bolometry: 8, 17 Equatorial ports: Vis / IR (outer wall): 1, 3, 9, 12 Ha spect (upper edge): 12 Bolometry: 1

  9. Info on the radiation damage to fibre optics Previous ITER assessment (in [1]): Optical fibres (silica) for the transmission of optical light can only be used outside the bioshield, with the exception for the transmission in the range 800-1400 nm, which is possible inside the cryostat volume but outside the primary vacuum window. LH window arcs: LH arc detection sensors in TS has peak sensitivity at 900 nm (IR). In addition, a study [2] shows that arcs near RF windows emit IR radiation before visible radiation, i.e. sensors should work in IR-range.  Silica fibres are OK up to the primary vacuum window. [1] R. Reichle et al., “Final Report for the EFDA contract 02-1003”, DIAG/NTT-2005.019 (2005) [2] D.L. Borovina et al., in Proc. of the 1999 Particle Accelerator Conference, New York (1999) p. 786

  10. Irradiation tests of fibres Irradiation tests have shown that fibres do exist that could be used up to the divertor [1]  these should be OK at the rear of the LH port plug as well. [1] R. Reichle et al., “Final Report for the EFDA contract 02-1003”, DIAG/NTT-2005.019 (2005)

  11. Actions Get diagnostic layouts of : Fast zones of VIS / IR systems Bolometry Ha spectroscopy Get in contact Spencer Pitcher (RO Langmuir probes) for design of Langmuir probes in ITER.

  12. WG4: Schematic layout of different diagnostic zones (4.1.1) (4.1.2) (4.1.3) Main transmission line (4.2.1) (4.2.2) Antenna front (1) Bio shield 4. DATA ACQUISITION 4.1 RF monitoring and fast interlocks 4.1.1Launcher instrumentation (primary vacuum area) 4.1.2Cryostat instrumentation (secondary vacuum area) 4.1.3 Main transmission line instrumentation 4.1.4 Klystron instrumentation 4.2 Antenna front diagnostics 4.2.1Edge density diagnostics and control 4.2.2Front face monitoring and control (4.1.4) Klystron area

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