SOLPS5 simulations of ELMing H-mode

Barbora Gulejová Swiss physical society 26/3/2008 1 of 19

Centre de Recherches en Physique des Plasmas

SOLPS5 simulations of

ELMing H-mode

Barbora Gulejová

Richard Pitts, David Coster, Xavier Bonnin,

Roland Behn, Marc Beurskens, Stefan Jachmich,

Jan Horáček, Arne Kallenbach



OUTLINE

SOLPS 5 code package

ELM simulation - theory

Simulation of Type III ELM at TCV

Simulation of Type I ELMing H-mode at JET

Code - experiment benchmark

Code - code benchmark

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ELMing H-mode = baseline scenario for plasma operation on ITER!

Edge localised mode (ELM)Edge localised mode (ELM)

H-mode Edge MHD instabilities Periodic bursts of particles and energy into the SOL

ELM leaves edge pedestal region in the form of a helical filamentary structure

localised in the outboard midplane region of the poloidal cross-section

Danger: divertor targets and main walls erosion first wall power deposition

Energy stored in ELMs: TCV 500 J JET 200kJ ITER ~ 1-10 MJ => unacceptable

MOTIVATION

Understanding of the ELM from formation to point of interaction with plasma facing components

= Important research goal!



SOLPS5 modelling of ELMing H-mode

• Type III & Type I ELMing H-mode

• TCV & JET

• benchmark SOLPS & EDGE2D/NIMBUS

1.)2.a)

2.b)

* contribute to understanding transport in the SOL : transient events => ELMs * interpretative modeling of both 1.) steady state and 2.) transient particle and heat fluxes during ELMing H-mode employing the SOLPS5 fluid/Monte Carlo code * rigorous benchmarking = seeking the possible agreement between 1.) experiment and simulation 2.) code and different code

MODEL: tool to understand and predict phenomena =>



SScrape-crape-OOff ff LLayer ayer PPlasma lasma SSimulationimulation Suite of codes to simulate transport in edge plasma of tokamaks

B2B2 - solves 2D multi-species fluid equations on a grid given from magnetic equilibrium

EIRENE EIRENE - kinetic transport code for neutrals based on

Monte - Carlo algorithm

SOLPS 5SOLPS 5 – coupled EIRENE + B2.5

Main inputs: * magnetic equilibrium * Psol = Pheat – Prad

core * upstream separatrix density ne

* EELM

Free parameters: cross-field transport coefficients (D┴, ┴, v┴)

B2 plasma background =>recycling fluxes

EIRENE

Sources and sinks due to neutrals and molecules

measured

systematicallyadjusted

Mesh

72 grid cells poloidallyalong separatrix

24 cells radially

D0 D1+ C0 C1+ C2+ C3+ C4+ C5+ C6+



Type III ELMing H-mode on TCVType III ELMing H-mode on TCVELMs - too rapid (frequency ~ 200 Hz) for comparison on an individual ELM basis => Many similar events are coherently averagedinside interval with reasonably periodic elms

Time-dependent ELM simulation

* starting from time-dependent pre-ELM steady state simulation * equal time-steps for kinetic and fluid parts of code, dt = 10-6 s

tpre ~ 2 ms

telm ~ 100 μs

tpost ~ 1 ms

Post-ELM phasePre-ELM phaseELM = particles and heat are thrown into SOL ( elevated cross-field transport coefficients)



Pre-ELM and ELM simulation - theoryPre-ELM and ELM simulation - theory

Ddr

dnT

dr

dTn

At

E

ELMELM

ELM ..2

5..

..2

Cross-field radial transport in the main SOL - complex phenomenaAnsatz:( D┴, ┴, v┴) – variation :

* Pure diffusion: v┴=0 everywhere

* More appropriate: Convection simulations with D┴= D┴

class

2 approaches

radially – transport barrier (TB)poloidally – no TB in div.legs

Instantaneous increase of the cross-field transport parameters D┴, ┴, v┴!

Simulation of ELM

1.) for ELM time – from experiment coh.averaged ELM = tELM = 10-4s2.) at poloidal location -> expelled from area AELM at LFS

Cross-field radial transport => approximate estimation of transport parameters during ELM corresponding to the given expelled energy WELM, tELM and AELM

AELM= 1.5m2

W = 600 JD ┴

┴

0

20

20 40

*



ELM is more convective than conductive !

<Teped>Δ.neped exceeds <neped>Δ .Teped

in the contribution to EELM =>

smaller TB

┴D ┴

TS measurements (R.Behn et al., PPCF 49 (2007)) => larger drop in ne than Te at the pedestal top =>

SOLPS : D increased more then during the ELM

100 times 10 times (2 times in SOL) + change of radial shape ! ETB collapse!

Type III TCV ELM simulation

Very good agreement !

AELM=1.5m2 – Gaussian function of multiplicators polloidally

1 ELM cycle of total 400 μs, * 100 μs before ELM

* ELM duration = tELM = 100μs =100 points during ELM event

* 200 μs after ELM

Upstream



SOLPS < Exp (LP)

factor ~ 1.5

SOLPS >> Exp (coav LP) ( R.Pitts,Nucl.Fusion 43 (2003)) factor ~ 3

Type III TCV ELM simulationDownstream



Type I ELMing H-mode on JET# 58569 Succesfully modelled by EDGE2D + NIMBUS by Arne Kallenbach (PPCF 46,2004)

Core LIDAREdge LIDAR Li beam ECE

Parameters

Bt = 2 T Ip = 2 MA

ne= 4x1019 m-3

P(SOL)= 12 MW

GAS PUFF from inner divertor !!

ELM parametersfelm ~ 30 HzΔWELM ~ 200 kJ

PIN ~ 14 MW PRAD (core)

Dalpha

Wdia

time



Benchmarking code-code SOLPS 5

B2.5 + EIRENE

fluid (Braginskii) kinetic (Monte Carlo), neutrals

EDGE2D + NIMBUS

fluid (Braginskii) kinetic (Monte Carlo), neutrals

(less complex then EIRENE!)

vs.



Pre-ELM model vs.experimentEDGE2D+NIMBUS SOLPS5

r-rsep [m]

0

22

0.05

Same AnsatzD,Chi,v

Same ne,Te,Tiupstreamprofiles -0.05



Pre-ELM vs. ELM simulation

0.1

0.05

0.05

EDGE2D+NIMBUS SOLPS5

ELMD x 20

Chi x 401ms

-0.05

0

0

0.05

0.05

-0.05



Model vs. experiment-targets(LP)EDGE2D+NIMBUS

LP

250

25

5

300

25

7

outer targetinner targetSOLPS5 outer target

r-rsep map2mid

r-rsep map2mid



Type I ELMing H-mode on JET

# 70224

Wdia

PIN ~ 20 MW PRAD (below Xpoint)

PRAD (core)

Dalpha Parameters

Bt = 3 T Ip = 3 MA

ne=6x1019 m-3

P(SOL)= 19 MW

No GAS PUFF !!

ν*ped ~0.03 -0.08 (expected for ITER!)

ELM parametersfelm ~ 2 HzΔWELM ~ 1 MJ

Simulated for the first time ! … with SOLPS5

Core LIDAREdge LIDAR Li beam HRTS ECE

Langmuir probes

time

=baseline scenario for QDT=10 burning plasma operation on ITER !!! To avoid divertor damage => maximum ΔWELM (ITER) ~ 1MJ (at TCV 0.005 MJ !!!)

= this is achievable on JET

Bolometry (A.Huber)radiation between ELMs



Core LIDAREdge LIDAR Li beam HRTS ECE

Simulation vs. experiment - upstream

First results for pre-ELM

* quite promising* unlike for TCV inward pinch radial profile necessary!!

D┴= 0.01 m2.s-1 in pedestal 1 m2.s-1 in SOLΧ┴= 0.7 m2.s-1 in pedestal 1 m2.s-1 in SOL

(TCV pedestal: D┴= 0.007 m2.s-1 Χ┴= 0.25 m2.s-1 )

ne [m-3]

Te [eV]

vperp [m.s-1]

inward pinch!

D [m2.s-1]Χ [m2.s-1]



Simulation vs.experiment - targets Outer targetInner target SOLPS LP LP

80

1,2

30

50

0.5

50

r-rsep r-rsep map2mid

r-rsep

r-rsep map2mid

Inner target – good agreement Outer target SOLPS Te too high!



CONCLUSIONS

Type III ELMing H-mode at TCV andType I ELMing H-mode at JET have been succesfully simulated by SOLPS5 both steady state and transient event

Agreement obtained between :code - experiment code - code

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Thank you for attention !

Documents

SOLPS5 simulations of ELMing H-mode