Advances in boronization on NSTX-Upgrade

Skinner, C.H.; Bedoya, F.; Scotti, F.; Allain, J.P.; Blanchard, W.; Cai, D.; Jaworski, M.; Koel, B.E.
Issue date: January 2017
Cite as:
Skinner, C.H., Bedoya, F., Scotti, F., Allain, J.P., Blanchard, W., Cai, D., Jaworski, M., & Koel, B.E. (2017). Advances in boronization on NSTX-Upgrade [Data set]. Princeton Plasma Physics Laboratory, Princeton University.
@electronic{skinner_ch_2017,
  author      = {Skinner, C.H. and
                Bedoya, F. and
                Scotti, F. and
                Allain, J.P. and
                Blanchard, W. and
                Cai, D. and
                Jaworski, M. and
                Koel, B.E.},
  title       = {{Advances in boronization on NSTX-Upgrade
                }},
  publisher   = {{Princeton Plasma Physics Laboratory, Pri
                nceton University}},
  year        = 2017
}
Abstract:

Boronization has been effective in reducing plasma impurities and enabling access to higher density, higher confinement plasmas in many magnetic fusion devices. The National Spherical Torus eXperiment, NSTX, has recently undergone a major upgrade to NSTX-U in order to develop the physics basis for a ST-based Fusion Nuclear Science Facility (FNSF) with capability for double the toroidal field, plasma current, and NBI heating power and increased pulse duration from 1–1.5 s to 5–8 s. A new deuterated tri-methyl boron conditioning system was implemented together with a novel surface analysis diagnostic. We report on the spatial distribution of the boron deposition versus discharge pressure, gas injection and electrode location. The oxygen concentration of the plasma facing surface was measured by in-vacuo XPS and increased both with plasma exposure and with exposure to trace residual gases. This increase correlated with the rise of oxygen emission from the plasma.

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