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9th Meeting of the ITPA Confinement Database & Modeling Topical Group, 3-6 October, 2005, St. Petersburg,. Multiple species extensions to the Weiland model and the Semi-predictive DEA code. P.I. Strand , With contributions/support from
9th Meeting of the ITPA Confinement Database & Modeling Topical Group, 3-6 October, 2005, St. Petersburg,
With contributions/support from
W.A. Houlberg (ORNL), H. Nordman (CTH), A. Eriksson (CTH), J. Weiland(CTH), G. Bateman(Lehigh), A. Kritz (Lehigh)
Straightforward extension of the Weiland drift wave model for ITG/TEM (Extended Drift Wave Model or ExtendeDWeiland Model):
Model can be used in different
settings and allows for physical
effects to be turned on/off to
study impact on transport/stability.
*DEA – Latin for ‘Goddess’
A semi-predictive particle transport code
R/LTi = R/LTe = 3.75, Te/Ti = 1, (all species), R/LnC = 2, ft =0.4, fC = 0.01
Slight asymmetry in fluxes enters through first order FLR effects in the baseline version
of Weilands fluid model. ITG driven mode only is excited for these parameters.
Impurity content (clockwise
1%, 3% and 5%)
R/LT = 3.75, all species
R/Ln = 2, Te/Ti = 1, ft = 0.4
R/Lne by ambipolarity
Tendency to equilibrate the density
scale-lengths between species remain
DIII-D like base case derived from Neon seeded shot #98775
r/a = 0.52
r/a = 0.7
Strong Z- dependence of the neoclassical flux as expected, shift of W pinch may be
explained through detailed balance of the thermodiffusion terms. Weak and inverted
Z-dependence of anomalous transport as expected but comparatively weak D contrib.
Full response when a non-trace species
is perturbed is much more complex and
would require more careful analysis.
We note that D has a outward flux for hollow profile leading to an even stronger
depletion and that it provides a pinch flow for already peaked profile whereas
Ne has the opposite trend. (Nominal values R/LnD = 1.12 and R/LnNe (2.07))
JET 37718 @ 53.8s
NB fuelled ELMy H-mode
Taken from the PR98
International Profile Tokamak
Initial condition for simulation shown:
Beam particle contribution turned off
Flat Te profile => reduced TEM drive
no anomalous inner
ITG mode and TE modes excited at r =0.25
Only Wall source available
Beam sources artificially turned off
The strong TEM driven pinch
weaken as density peaks up.
At 53.9s pinch has vanished and
A weak outward flux persist for
remainder of simulation
Neoclassical transport dominated
by Ware pinch =>
peaking of nD(0).
Axial peaking off-set by kinetic
Ballooning mode as density increases.
Density profile determined by
Balance between different neoclassical and anomalous terms.
Two new code developments
Complimentary exploration tool
To large scale transport codes
Effect of impurities on D and T transport in core plasmas
Comparison with neoclassical fluxes
Physics background: J. Weiland, IoP Publ., Bristol, 2000, "Collectives Modes in Inhomogeneous Plasma”, and references therein
Numerical Techniques: G. Bateman, J. Weiland, H. Nordman, J. Kinsey. C. Singer, Phys. Scripta, 51, (1995)
Implementation: P. Strand, H. Nordman, J. Weiland, J.P. Christiansen, Nucl. Fusion, 38 (1998)
NCLASS: W.A.Houlberg et al., Phys. Plasmas 4 (1997), 3230
IPD databases: "The International Multi-Tokamak Profile Database", Nucl. Fus 40 (2000), 1955 And ITER Physics Basis, Chapter 2, Nucl. Fus, 39 (1999), 2175
0.75 * Grad Ti
1.25* grad Ti
Effect of changing the background temperature gradients: Major change in anomalous
transport as expected. Higher Z neoclassical estimates more strongly affected than
lower Z. Results of analysis method strongly dependent on resolution of background
profiles and their gradients..