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Author: Gregory W. Hammett
Requested Type: Poster
Submitted: 2017-03-18 01:06:24

Co-authors: E.L. Shi, A. Hakim, T. Stoltzfus-Dueck

Contact Info:
Princeton University, Princeton Plasma Physics Lab
100 Stellarator Road
Princeton, NJ   08540
USA

Abstract Text:
3D2V continuum gyrokinetic simulations of electrostatic plasma turbulence have been performed using the full-F discontinuous-Galerkin code Gkeyll. Results will be shown for simulations of the LArge Plasma Device (LAPD) with straight magnetic fields, and of a helical model of a tokamak scrape-off layer (SOL), for parameters motivated by an NSTX case. Although there are a number of simplifications in the physics model and the geometry at this point in the development of the code, these simulations include some key elements of a fusion-device SOL: localized sources to model plasma outflow from the core, very steep gradients and bad-curvature that drive large amplitude turbulence, and parallel losses to end plates with model sheath boundary conditions. We do not yet treat open and closed field lines simultaneously and here focus on the open-field line SOL. The magnetic field is modeled as a toroidal field plus a vertical field (a helical field similar to Helimak or Torpex). Other approximations at present include using the long-wavelength limit of gyrokinetics (like some drift-kinetic equations, but using the long-wavelength gyrokinetic Poisson equation to determine the potential), and using a uniform density in the polarization term (similar to a Boussinesq approximation in fluid equations, neglecting some full-F effects at present). The sheath model allows currents to flow through the walls. The LAPD results are qualitatively similar to previous fluid simulations [1,2] and experimental measurements of fluctuation amplitudes and spectra [2,3]. The NSTX-like simulations give large amplitude blobs and show features indicating a strong drive by bad curvature. Supported by US DOE Contract No. DE-AC02-09CH11466.

[1] Rogers, B. N. & Ricci, P. 2010, Phys. Rev. Lett. 104, 225002
[2] Friedman, B., Carter, T. A., Umansky, et al. 2012, Phys. Plasmas 19, 202307
[3] Carter, T. A. & Maggs, J. E. 2009, Phys. Plasmas 16, 012304

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