Characterization of Chemical Sputtering Using the Mark II DIMES Porous Plug Injector in Attached and Semi-detached Divertor Plasmas of DIII-D

Conference · Thu Jan 01 00:00:00 EST 2009

OSTI ID:1019375

McLean, A G ^[1]; Davis, J W ^[1]; Stangeby, P C ^[1]; Allen, S L ^[2]; Boedo, J A ^[3]; Bray, B D ^[4]; Brezinsek, S ^[5]; Brooks, N H ^[4]; Fenstermacher, M E ^[2]; Groth, M ^[2]; Haasz, A A ^[1]; Hollmann, E M ^[3]; Isler, Ralph C ^[6]; Lasnier, C J ^[2]; Mu, Y ^[1]; Petrie, T W ^[4]; Rudakov, D L ^[3]; Watkins, J G ^[7]; West, W P ^[4]; Whyte, D G ^[8] ; Wong, C P. C. ^[4]

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1. University of Toronto Institute for Aerospace Studies
2. Lawrence Livermore National Laboratory (LLNL)
3. University of California, San Diego
4. General Atomics, San Diego
5. Forschungszentrum Julich, Julich, Germany
6. ORNL
7. Sandia National Laboratories (SNL)
8. Massachusetts Institute of Technology (MIT)

An improved, self-contained gas injection system for the divertor material evaluation system (DIMES) on DIII-D has been employed for in situ study of chemical erosion in the tokamak divertor environment. To minimize perturbation to local plasma, the Mark II porous plug injector (PPI) releases methane through a porous graphite surface at the outer strike point at a rate precisely controlled by a micro-orifice flow restrictor to be approximately equal as that predicted for intrinsic chemical sputtering. Effective photon efficiencies resulting from CH(4) are found to be 58 +/- 12 in an attached divertor (n(e) similar to 1.5 x 10(13)/cm(3), T(e) similar to 25 eV, T(surf)similar to 450 K), and 94 +/- 20 in a semi-detached cold divertor (n(e) similar to 6.0 x 10(13)/cm(3), T(e) similar to 2-3 eV, T(surf) similar to 350 K). These values are significantly more than previous measurements in similar plasma conditions, indicating the importance of the injection rate and local re-erosion for the integrity of this analysis. The contribution of chemical versus physical sputtering to the source of C(+) at the target is assessed through simultaneous measurement of CII line, and CD plus CH-band emissions during release of CH(4) from the Pill, then compared with that seen in intrinsic sputtering. (C) 2009 Elsevier B.V. All rights reserved.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1019375
• Resource Relation: Conference: 18th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices, Toledo, Spain, 20080526, 20080530
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
03 NATURAL GAS
DIVERTORS
DOUBLET-3 DEVICE
EVALUATION
GAS INJECTION
GRAPHITE
METHANE
PHOTONS
PLASMA
SPUTTERING
TARGETS
Erosion