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...