nicolas fedorczak

N. Fedorczak O-26 PSI 2010 N. Fedorczak O-26 PSI 2010 San Diego San Diego 1i

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Nicolas FedorczakNicolas Fedorczak

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Poloidal mapping of turbulent Poloidal mapping of turbulent transporttransport

in SOL plasmas.in SOL [email protected]@cea.fr

G. Bonhomme, F. Brochard, H. Bufferand, G. Ciraolo, M. G. Bonhomme, F. Brochard, H. Bufferand, G. Ciraolo, M. Farge,Farge,Ph. Ghendrih, J.P. Gunn, P. Hennequin , L. Isoardi, R. Ph. Ghendrih, J.P. Gunn, P. Hennequin , L. Isoardi, R. Nguyen, Nguyen, C. Reux, F. Schwander, P. Tamain, L. VermareC. Reux, F. Schwander, P. Tamain, L. Vermare

J.P. GunnJ.P. Gunn


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Poloidal mapping of turbulent transport in SOL plasmasPoloidal mapping of turbulent transport in SOL plasmas

Multi-diagnostics investigation of transport at the edge Multi-diagnostics investigation of transport at the edge

I. Fast visible imaging :I. Fast visible imaging : Evidences of transport phenomena & asymmetriesEvidences of transport phenomena & asymmetries

II. Local turbulence with probe :II. Local turbulence with probe : blobby ExB convectionblobby ExB convection

III. Steady-state flows III. Steady-state flows (probe)(probe) Poloidal mapping of the radial Poloidal mapping of the radial fluxflux

Rake probeturbulence

Fast visible imagingturbulence

Tunnel Probe// flow


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HFS injectionexp ~ 20 µs

LFS injectionexp ~ 20 µs

HFS LFS

2. Fast visible imaging : evidences of transport phenomena2. Fast visible imaging : evidences of transport phenomena

Similar gas injections on Similar gas injections on High Field SideHigh Field Side / / Low Field Low Field SideSide

Clear evidence of transport asymmetry --> filaments on the Low Field Side Clear evidence of transport asymmetry --> filaments on the Low Field Side

Fast imaging in the visible range --> fluctuations of SOL plasma densityFast imaging in the visible range --> fluctuations of SOL plasma density

Aligned with magnetic field & propagation (r,Aligned with magnetic field & propagation (r,)) filaments with kfilaments with k//// >0 >0


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2. Plasma filaments : not a SOL phenomenon 2. Plasma filaments : not a SOL phenomenon

SteadySteady--statestate picturepicture snapshotsnapshot MagneticMagnetic reconstructionreconstruction

LCFSLCFS

• Other experiment : stationary fully detached plasmas (3-4 sec.)Other experiment : stationary fully detached plasmas (3-4 sec.)

Again,Again, field alignedfield aligned structures only on thestructures only on the Low Field SideLow Field Side

+ local conditions ( + local conditions ( * , * , P P ) similar to SOL) similar to SOL

--> emissive ring in the confined region (r/a ~0.5 )--> emissive ring in the confined region (r/a ~0.5 )

filaments filaments k k//// > 0 + open / closed field lines > 0 + open / closed field lines

20ms picture20ms picture 20µs 20µs snapshotsnapshot


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3. Local fluctuations : blobby ExB radial transport3. Local fluctuations : blobby ExB radial transport

EnBvn r

turbr

~~1~~

• Intermittent flux with a residual time averaged amplitudeIntermittent flux with a residual time averaged amplitude

Turbulent radial fluxTurbulent radial flux : :

rturbr Vn

~

• Good coupling between EGood coupling between E & n & nee for radial transport (all time for radial transport (all time scales)scales)

1-ms30

rV

1-ms 300

rV

Transport coefficient :Transport coefficient :

probeprobe

SOLSOL

LCFSLCFS

BBT T IIPP


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3. Local fluctuations : blobby ExB radial transport3. Local fluctuations : blobby ExB radial transport

Whole radial profiles are treated in term of transport coefficient: Whole radial profiles are treated in term of transport coefficient:

S

rn c

vL

e //~ few cm.

Value coherent with density Value coherent with density profileprofile

Need of a poloidal mapping of the radial flux in the Need of a poloidal mapping of the radial flux in the SOLSOL

Radial increase of the velocity Radial increase of the velocity measured at the midplanemeasured at the midplane

BI

EIV

SAT

floatSATeff

r

~~

3030BI

EIV

SAT

floatSATeff

r

~~

3030TCVTCV Garcia, Pitts PPCF 2007 Garcia, Pitts PPCF 2007Alcator-C modAlcator-C mod Moyer JNM 1997 Moyer JNM 1997

??

Probe TSProbe TS

Probe TCVProbe TCVAlcator CAlcator C--modmodDIIIDIII --DD

JETJET


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4. Steady-state flows and flux asymmetries : evidences4. Steady-state flows and flux asymmetries : evidences

Flow transition when rolling the plasma up-down on outboard limiters.Flow transition when rolling the plasma up-down on outboard limiters.

Main contribution from particle source asymmetryMain contribution from particle source asymmetry

MM//// (@ Top) & plasma position (@ Top) & plasma position

• Near sonic // flows usually measured at the plasma topNear sonic // flows usually measured at the plasma top

//M

LCFSLCFS

//MLCFSLCFS

J.P. Gunn JNM 2007J.P. Gunn JNM 2007


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HFS LFS

Probe

radial source

15 % 85 %

M// ~0.4

profile radial Snc

profile radial //M

SrTOT

SrLFS

SrHFS

profile radial rS

4. Steady-state flows and radial flux : Amplitude & asymmetry4. Steady-state flows and radial flux : Amplitude & asymmetry

LIMITER

LIMITER

LFSHFS

LCFS

probe// sink

radial source Sr

source

Initial dataInitial data

Line integrated Line integrated radial flux Sradial flux Srr

L. Isoardi & al. P2. 58 L. Isoardi & al. P2. 58

G. Ciraolo et al. P2. 60 G. Ciraolo et al. P2. 60

E. Serre P2. 61 E. Serre P2. 61


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4. Radial flux tailoring : poloidal mapping4. Radial flux tailoring : poloidal mapping

Fine mapping around the outboard Fine mapping around the outboard midplane by varying the SOL midplane by varying the SOL magnetic topologymagnetic topology

Radial particle flux centered on the outboard midplane ( Radial particle flux centered on the outboard midplane ( ~ ~ 50 ° ) 50 ° )LIMITER

LIMITER

LFSHFS

probe// sink 2nd limiter

LCFSMulti-limiter SOL shaping: Multi-limiter SOL shaping: G. Ciraolo P2. 60 G. Ciraolo P2. 60


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5. Mutli-diagnostics coherency5. Mutli-diagnostics coherency

Fast visible imagingFast visible imaging Convection of density filamentsConvection of density filaments Evidence of asymmetriesEvidence of asymmetries

ProbesProbesLocal blobby ExB transportLocal blobby ExB transport

consistent with consistent with Global particle balanceGlobal particle balance

(steady-state flux mapping)(steady-state flux mapping)

SOL transport : LFS blobby ExB convection + SOL transport : LFS blobby ExB convection + kk//// >0 >0

Radial flux poloidal mapping @ LCFSRadial flux poloidal mapping @ LCFS


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6. Multi-Tokamak coherency : Top to midplane measurements6. Multi-Tokamak coherency : Top to midplane measurements

Local ExB flux @ Top + Local ExB flux @ Top + Poloidal flux mappingPoloidal flux mapping (function of (function of radius) radius)

Usual behaviorUsual behavior - Tore Supra- Tore Supra - JET- JET

Usual behaviorUsual behavior - TCV- TCV - Alcator C-mod- Alcator C-mod - DIII-D- DIII-D

Extrapolated transport behavior coherent with midplane measurementsExtrapolated transport behavior coherent with midplane measurements

Radial decrease @ Radial decrease @ TopTop

n

vn r~~

n

vn r~~

Top probe Top probe

rr(())

midplane midplane

Top Top midplane extrapolation midplane extrapolation

Radial increase @ Radial increase @ midplanemidplane


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7. Conclusion & perspectives7. Conclusion & perspectives

Radial particle transport in the SOL :Radial particle transport in the SOL :

Driver of SOL // flow Driver of SOL // flow Boundary conditions for core rotation. Boundary conditions for core rotation.

Do not depend on magnetic topology - open / closed field linesDo not depend on magnetic topology - open / closed field lines

highly asymmetrical : centered on outboard midplane highly asymmetrical : centered on outboard midplane + k+ k////>0 >0 modes.modes.

High fraction due to ExB density convections ( ~ 100%)High fraction due to ExB density convections ( ~ 100%)

ALCATOR C-mod :ALCATOR C-mod : LaBombard NF 2004 LaBombard NF 2004 TORE SUPRA :TORE SUPRA : P. Hennequin EPS 2010 P. Hennequin EPS 2010

- X-point / limiter- X-point / limiter Involved in apparent incoherencies :Involved in apparent incoherencies :

Local / Global particle flux balanceLocal / Global particle flux balance Multi machine comparisonMulti machine comparison

Realistic transport parameters for simulations of edge plasmasRealistic transport parameters for simulations of edge plasmasSOLEDGE 2D / SOLEDGE 3D SOLEDGE 2D / SOLEDGE 3D

Kelvin-Helmotz instabilityKelvin-Helmotz instability F. Schwander F. Schwander P1. 35 P1. 35

Multi-limiters SOL profilesMulti-limiters SOL profiles G. Ciraolo, L. Isoardi, H. Bufferand G. Ciraolo, L. Isoardi, H. Bufferand

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