2005 47th Annual Meeting of the Division of Plasma Physics
Monday–Friday, October 24–28, 2005;
Denver, Colorado
Session KI1: Turbulence and Transport: Experiment and Simulation
9:30 AM–12:30 PM,
Wednesday, October 26, 2005
Adam's Mark Hotel
Room: Plaza Ballroom ABC
Chair: Charles Greenfield, General Atomics
Abstract ID: BAPS.2005.DPP.KI1.4
Abstract: KI1.00004 : Gyrokinetic simulations of ETG Turbulence*
11:00 AM–11:30 AM
Preview Abstract
Abstract
Author:
William Nevins
(LLNL)
Recent gyrokinetic simulations of electron
temperature gradient
(ETG) turbulence [1,2] produced different
results despite similar plasma parameters.
Ref.[1] differs from Ref.[2] in that
[1] eliminates magnetically trapped particles
($ r/R=0 $), while [2] retains magnetically
trapped particles ($ r/R \approx 0.18 $).
Differences between [1] and [2] have been
attributed to insufficient phase-space
resolution and novel physics associated
with toroidicity and/or global
simulations[2].
We have reproduced the results reported
in [2] using a flux-tube, particle-in-cell
(PIC) code,
PG3EQ[3], thereby eliminating
global effects as the cause of the
discrepancy. We observe late-time decay
of ETG turbulence and the steady-state
heat transport in agreement with [2],
and show this results from discrete
particle noise.
Discrete particle noise is a numerical artifact,
so both the PG3EQ simulations reported here and
those reported in Ref.[2] have little to
say about steady-state ETG turbulence and
the associated anomalous electron heat transport.
Our attempts to benchmark PIC and
continuum[4]
codes at the plasma parameters used
in Ref.[2] produced very large,
intermittent transport. We will present an
alternate benchmark point for ETG turbulence,
where several codes reproduce
the same transport levels. Parameter scans
about this new benchmark point will be used
to investigate the parameter dependence of
ETG transport and to elucidate saturation mechanisms
proposed in Refs.[1,2] and elsewhere[5-7].\\
\noindent
*In collaboration with A. Dimits (LLNL),
J. Candy, C. Estrada-Mila (GA),
W. Dorland (U of MD),
F. Jenko, T. Dannert (Max-Planck Institut),
and G. Hammett (PPPL).
Work at LLNL performed for
US DOE under Contract W7405-ENG-48.\\
\noindent
[1]~F. Jenko and
W. Dorland, PRL
{\bf89}, 225001 (2002).\\
\noindent
[2]~Z. Lin et al, 2004 Sherwood Mtg.;
2004 TTF Mtg.;
Fusion Energy 2004 (IAEA, Vienna, 2005);
Bull. Am. Phys. Soc. (November, 2004);
2005 TTF Mtg.;
2005 Sherwood Mtg.;
Z. Lin, et al, Phys. Plasmas
{\bf12}, 056125 (2005). \\
\noindent
[3]~A.M. Dimits, et al,
Phys. Rev. Letters
{\bf77}, 71 (1996).\\
\noindent
[4]~J. Candy, and R.E. Waltz,
JCP {\bf186}, 5445 (2003); F. Jenko, et al,
Phys. Plasmas {\bf7}, 1905 (2000).\\
\noindent
[5]~S.C. Cowley, et al,
Phys. Fluids B {\bf3}, 2767 (1991).\\
\noindent
[6]~C. Holland and P. Diamond,
submitted to Physics Letters A (2005).\\
\noindent
[7]~F. Jenko, Theory of
Fusion Plasmas (2002).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2005.DPP.KI1.4