5-9 September 2016
Prague Congress Centre
Europe/Prague timezone

P1.058 ITER Erosion/Deposition Monitor Diagnostic

5 Sep 2016, 14:20
1h 40m
Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Foyer 2A (2nd floor), 3A (3rd floor)

Prague Congress Centre

5. května 65, Prague, Czech Republic
Board: 58
Poster D. Diagnostics, Data Acquisition and Remote Participation P1 Poster session

Speaker

Nancy Ageorges (Kampf Telescope Optics)

Description

In ITER, like in any fusion reactor, the plasma-wall interaction is unavoidable. It leads to material erosion and potential re-deposition or other surface morphology changes, as well as dust formation and tritium retention. The decision to start ITER operations with a full-W divertor has significantly reduced the expected erosion of the divertor target making observation of the target during discharges unnecessary. Co-deposition of beryllium is expected to be limited in the high heat flux region near the strike-point because of the high surface temperature in this area. Strong surface morphology changes can, however, happen in the strike-point area due to roughening/cracking and possibly melting caused by ELMs. A diagnostic for surface morphology measurements between discharges is deemed necessary to check for the appearance and development of tungsten surface damage, initially in the micrometer range. To monitor the fine morphology changes of the target surfaces non-invasive remote sensing method is preferred, and after a dedicated workshop on Erosion, Deposition, Dust and Tritium retention, the dual beam speckle interferometry method has been recommended for this diagnostic. This technique based on the Michelson interferometer scheme is proposed for measuring the surface topology of the vertical parts of the inner and outer divertor targets, where plasma – wall interactions are the most intense. The evolution of the morphology will be characterized based on observations made before and after plasma shots. To allow a proper analysis (absolute calibration), reference surfaces are needed. They are currently placed ~35mm behind the surface of the tungsten monoblocks. The proposed diagnostic is unique in its concept and realization and has so far not been tested in a real working tokamak environment. This paper will review the requirements and objectives of this diagnostic, present the opto-mechanical design and detail the numerous challenges faced (limited space, high loads, vibration sensitivity, etc).

Co-authors

Dirk Kampf (Kampf Telescope Optics, Munich, Germany) George Vayakis (ITER Organisation, St Paul Lez Durance Cedex, France) Govindarajan Jagannathan (ITER Organisation, St Paul Lez Durance Cedex, France) Gregory De Temmerman (ITER Organisation, St Paul Lez Durance Cedex, France) Mike Walsh (ITER Organisation, St Paul Lez Durance Cedex, France) Nancy Ageorges (Kampf Telescope Optics, Munich, Germany) Roger Reichle (ITER Organisation, St Paul Lez Durance Cedex, France)

Presentation Materials

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