Comparing Definitions of Detachment on DIII-D

POSTER

Abstract

DIII-D’s broad range of divertor diagnostics are used to characterize both the onset and trajectory of H-mode detachment for a variety of detachment definitions. Varying definitions of detachment focus on pressure loss, dropping electron temperature, rising neutral pressure, ion flux roll-over, and heat-flux reduction. Clearly defining the state of detachment therefore relies on combining diagnostics so that the relative importance of each physical process can be compared. Identifying the sensitivity of these processes to upstream conditions and radiative power fraction facilitates identifying unstable detachment regimes. On DIII-D, detachment identification is achieved using Langmuir probes, Thompson scatting, EUV/VUV, visible and near-infrared spectroscopy, visible and IR imaging, coherence imaging, neutral pressure gauges, and bolometry. ELM “burn through” in partially detached plasmas is discussed whereby periodic reattachment can occur with associated rises in heat flux and high energy particle transport to the divertor whose magnitude depends on an interplay between degree of detachment and pedestal characteristics.

Presenters

  • Cameron M Samuell

    Lawrence Livermore Natl Lab, LLNL, Lawrence Livermore National Laboratory, USA

Authors

  • Cameron M Samuell

    Lawrence Livermore Natl Lab, LLNL, Lawrence Livermore National Laboratory, USA

  • Steven L Allen

    Lawrence Livermore National Lab, Lawrence Livermore Natl Lab, LLNL, Lawrence Livermore National Laboratory, USA

  • Max E Fenstermacher

    Lawrence Livermore Natl Lab, Lawrence Livermore National Lab, Lawrence Livermore National Laboratory, USA

  • Aaro E Jaervinen

    Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory, LLNL, Lawrence Livermore National Laboratory, USA

  • Charles J Lasnier

    Lawrence Livermore Natl Lab

  • Adam McLean

    Lawrence Livermore National Lab, LLNL, Lawrence Livermore Natl Lab, Lawrence Livermore National Laboratory, USA

  • Joseph L Barton

    Sandia Natl Labs

  • Jonathan Watkins

    Sandia National Laboratory, Sandia Natl Labs, Sandia National Laboratories, Sandia National Lab, General Atomics - San Diego, SNL, Sandia National Laboratory, USA

  • Jose A Boedo

    Univ of California - San Diego

  • Houyang Guo

    General Atomics - San Diego

  • Anthony W Leonard

    General Atomics - San Diego, General Atomics, USA, General Atomics

  • Auna Louise Moser

    General Atomics - San Diego

  • Dan M Thomas

    General Atomics - San Diego, General Atomics

  • Morgan W. Shafer

    Oak Ridge National Laboratory, Oak Ridge National Laboratory, USA

  • Robert Wilcox

    Oak Ridge National Laboratory, ORNL, Oak Ridge National Laboratory, USA

  • Huiqian Wang

    Oak Ridge Associated Universities, General Atomics - San Diego, Oak Ridge Associated University, ORAU, Oak Ridge, TN, USA, Oak Ridge Associated Universities, USA, Oak Ridge Associated Universities, USA, General Atomics