Direct Measurements of Chemical Sputtering Yield and Photon Efficiencies in the DIII-D Divertor

ORAL

Abstract

Intrinsic chemical erosion yield near the outer strike point has been measured in-situ in DIII-D to be $\sim$2.6\% in attached divertor plasma and $\sim$1.7\% in semi-detached divertor plasma. These values are close to theoretical predictions and lab experiments. In fully detached conditions, as will occur at the ITER targets, near total extinction of the CH band occurred which is not predicted or included in current ITER modeling. Measurements were made with an artificial methane injection rate nearly equal to the expected intrinsic chemical erosion rate. Photon efficiencies for CH, CII and C$_2$ dimer from the breakup of injected CH$_4$ yielded significantly lower values than previous results at higher puff rates, underscoring the importance of minimizing perturbation to the local plasma.

*Supported by the U SDOE under DE-AC52-07NA27344, DE-FC02-04ER54698, DE-FG02-07ER54917, DE-AC05-00OR22725, DE-AC04-94AL85000.

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Authors

  • A.G. McLean

  • P.C. Stangeby

  • Y. Mu

  • J.W. Davis

  • A.A. Haasz

    • U. Toronto

  • S.L. Allen

    • LLNL
    • Lawrence Livermore National Laboratory

  • M.E. Fenstermacher

    • Lawrence Livermore National Laboratory
    • LLNL

  • M. Groth

    • LLNL
    • Lawrence Livermore National Laboratory

  • C.J. Lasnier

    • LLNL
    • Lawrence Livermore National Laboratory

  • B.D. Bray

  • N.H. Brooks

    • General Atomics

  • T.H. Osborne

    • General Atomics

  • T.W. Petrie

    • General Atomics

  • W.P. West

    • General Atomics
    • GA

  • C.P.C. Wong

    • General Atomics
    • GA

  • D.G. Whyte

    • MIT

  • J.A. Boedo

    • UCSD

  • D.L. Rudakov

    • UCSD
    • University of California-San Diego

  • R.E. Isler

    • ORNL

  • J.G. Watkins

    • SNL
    • Sandia National Laboratory
    • Sandia National Laboratories

  • S. Brezinsek

  • M. Jakubowski

    • FZ-Juelich