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Institut für PlasmaforschungUniversität Stuttgart
Plasma Turbulenceat the Transition from
Closed to Open Fieldlines
Mirko Ramisch
07.07.2009
2CWGM5, Stuttgart, 7.7.2009
Edge/SOL - transition
[J. Horacek et al]Drift-
wavesInterchange-instabilities
3CWGM5, Stuttgart, 7.7.2009
Edge/SOL – dynamics in TJ-K
Reduced confinement region
5CWGM5, Stuttgart, 7.7.2009
„Blob“-dynamics
[T.Happel et al, PRL 102, 2009]
6CWGM5, Stuttgart, 7.7.2009
Probability density function (PDF) of Isat
[P. Abdul]
S=-0.6 S=+0.9
7CWGM5, Stuttgart, 7.7.2009
Probe array in AUG
14 carbon pins
Poloidal distance 3mm
8CWGM5, Stuttgart, 7.7.2009
Probability density function (PDF) of Isat
#22505
AUG:
“holes” “blobs”
[B. Nold]
9CWGM5, Stuttgart, 7.7.2009
Phase velocity shear layer
10CWGM5, Stuttgart, 7.7.2009
Probe arrangement
floating potential
ion-saturation current
[C. Lechte]
11CWGM5, Stuttgart, 7.7.2009
Radial profiles
12CWGM5, Stuttgart, 7.7.2009
Distribution of Ii,sat fluctuations
No indication of density holes Change in number of positive events (blobs) in edge shear region
13CWGM5, Stuttgart, 7.7.2009
Propagation of blobs
Udia,i
UExB
14CWGM5, Stuttgart, 7.7.2009
t: time dependence
15CWGM5, Stuttgart, 7.7.2009
Potential raise at plasma edge
-2
-10
12
0.81
0.82
0.83
0.84
0.85
20
40
60
80
100
r-rsep (cm)time (s)
f (V
)
16CWGM5, Stuttgart, 7.7.2009
Turbulent transport
-2-1
01
2
0.81
0.82
0.83
0.84
0.85
0
5
x 104
r-rsep (cm)time (s)
(a
.u.)
cosv~n~rvnr
17CWGM5, Stuttgart, 7.7.2009
Common: increasing number of intermittent events („blobs“) across separatrix
Uncommon: reversal of phase velocity (mechanism?), „holes“
Insights from other experiments needed to work out differences and universalities, role of islands, mechanism of velocity reversal...