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Max-Planck-Institutfür Plasmaphysik
Combined analysis of light
impurity transport in AUG and
JET
P. Manas, Y. Camenen, S. Benkadda, H. Weisen, C. Angioni, F. J.
Casson, C. Giroud, M. Gelfusa, and JET contributors for C transport
studies at JET
A. Kappatou, R. M. McDermott, T. Pütterich, C. Angioni, R. Dux, R. J. E.
Jaspers, E. Viezzer, M. Cavedon, R. Fischer, M. Willensdorfer, G. Tardini
and the ASDEX Upgrade Team for He and B studies at AUG
Light impurity transport in AUG and JET P. Manas / ITPA 16th
Theoretical background
• Modelling of Impurity transport
Light impurity transport in AUG and JET P. Manas / ITPA 16th 2
• Convective mechanisms:
• Steady state + no sources → Peaking factor
Thermo-diffusion Roto-diffusion Constant pinch
Motivations
• Stress theory vs experiment
Assess the impact of roto-diffusion
Theory consistent with different Z impurities?
Do we have all the ingredients in the theory?
Quantitative prediction of impurity profiles?
Light impurity transport in AUG and JET P. Manas / ITPA 16th 3
AUG database
• H-mode, deuterium plasmas
• 5 shots, several time slices → 131
steady states
• NBI: 2.5 – 7.5 MW BT: 2.5 T
• ECRH: 0 – 2.5 MW Ip: 600 kA
• ne: 4.8 – 8.2x1019 m-3 q95: 7
Light impurity transport in AUG and JET P. Manas / ITPA 16th 4
AUG database
• CXRS
• Helium and boron profiles
• Helium (Plume effect)
• Boron profiles:
Peaked at low NBI
Flat/Hollow at high NBI
• He profiles:
Always peaked
Light impurity transport in AUG and JET P. Manas / ITPA 16th 5
JET database
• H-mode plasmas
• Deuterium plasmas
• 156 shots
• Carbon wall era
• Ip: 1 – 2 MA
• BT: 1.4 – 3.4
• q95: 4 – 9.6
• ne: 2.6 – 7.7x1019 m-3
Light impurity transport in AUG and JET P. Manas / ITPA 16th 6
JET database
Light impurity transport in AUG and JET P. Manas / ITPA 16th 7
• NBI: 2.6 – 22MW
• Mainly 10 – 22 MW
• ICRH: 0 – 5 MW
• Mach number: 0.1 – 0.38
• u’: 0 – 2.5
• Typical carbon density
profiles
Hollow (core)
Peaked (edge)
• Interested in core region
Plasma parameters (midradius)
AUGR/Lti 3 – 7
R/Lte 3.4 – 7
R/Ln 0 – 3.5
u’ -0.15 – 1
R/LnB -0.3 – 1.8
R/LnHe 0 – 3.4
NBI (MW) 2.5 – 7.5
ECRH (MW) 0 – 2.5
Te / Ti 1 – 1.6
u 0.08 – 0.25
ν* 0.14 – 0.6
ρ* 1.10-3
JET5 – 10 R/Lti
3 – 7.5 R/Lte
0 – 4.4 R/Ln
0.8 – 2.1 u’
-5 – 2 R/LnC
2.6 – 22 NBI (MW)
0 – 5 ICRH (MW)
0.6 – 1.4 Te / Ti
0.18 – 0.32 u
2.9 10-3 – 0.1 ν*
1 – 2.7 10-3 ρ*
Light impurity transport in AUG and JET P. Manas / ITPA 16th 8
Plasma parameters (midradius)
AUGR/Lti 3 – 7
R/Lte 3.4 – 7
R/Ln 0 – 3.5
u’ -0.15 – 1
R/LnB -0.3 – 1.8
R/LnHe 0 – 3.4
NBI (MW) 2.5 – 7.5
ECRH (MW) 0 – 2.5
Te / Ti 1 – 1.6
u 0.08 – 0.25
ν* 0.14 – 0.6
ρ* 1.10-3
JET5 – 10 R/Lti
3 – 7.5 R/Lte
0 – 4.4 R/Ln
0.8 – 2.1 u’
-5 – 2 R/LnC
2.6 – 22 NBI (MW)
0 – 5 ICRH (MW)
0.6 – 1.4 Te / Ti
0.18 – 0.32 u
2.9 10-3 – 0.1 ν*
1 – 2.7 10-3 ρ*
Light impurity transport in AUG and JET P. Manas / ITPA 16th 8
AUG + JET databases
Light impurity transport in AUG and JET P. Manas / ITPA 16th 10
• Same range of R/Lne
• Hollow profiles in JET
• Higher R/LTi and u’ in JET (flattening from ECRH in
ASDEX)
• → Hollow profiles?
AUG + JET databases
Light impurity transport in AUG and JET P. Manas / ITPA 16th 11
• Low R/Lti and u’ with ECRH
• Trends of R/LnZ with R/Lti and u’ (JET data scattered)
• However for similar values of u’ and R/Lti in AUG and JET,
very hollow C profiles / peaked B profiles
• Does the modelling recover these trends?
Modelling hypotheses
• Local, flux-tube gyrokinetic simulations (GKW)
Gradient driven
Linear and nonlinear
Electromagnetic
Linearised Fokker-Planck operator (with ad-hoc field
particle part)
MHD equilibrium (CHEASE)
Coriolise drift
Centrifugal effects
• Quasilinear approach (consistent with few
nonlinear simulations)
Light impurity transport in AUG and JET P. Manas / ITPA 16th 12
Dominant instabilities (core)
• Main instabilities at
r/a = 0.5 → ITG
• Outward CT, Cu : flatten
• Inward Cp : peak
• Quasilinear rule
(normalised):
• Valid against NL spectra
Light impurity transport in AUG and JET P. Manas / ITPA 16th 13
Transport coefficients
Light impurity transport in AUG and JET P. Manas / ITPA 16th 14
• Higher CT for Helium (1/Z
dependency)
• Inward CT and Cu for few
TEM cases
• Cu and CT are comparable
in JET
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 15
• AUG:
Experimental and modelled peaking factor are correlated to R/Lti
Underprediction not clearly correlated to R/Lti for He
Change from underprediction to overprediction for B at high R/Lti
• JET
Modelled peaking factor correlated to R/Lti but not EXP one
Hollow profiles for similar to AUG R/LTi
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 16
• AUG:
Underprediction not clearly correlated to u’ for He
Change from underprediction to overprediction for B at high u’
• JET
Better agreement at high u’ (roto-diffusion)
Hollow profiles at similar to AUG u’
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 17
• JET
Quantitative agreement at low
Te/Ti (due to roto-diffusion)
Systematic disagreement at
Te/Ti > 1
Hollow EXP profiles predicted
peaked
• AUG
Two different EXP trends with
NBI and ECRH
Not recovered in the modelling
Underprediction for He and B
Maximum for Te/Ti = 1.2
Overprediction of B at high NBI
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 18
• Boron Modelling:
Underprediction (low NBI)
Overprediction (High NBI)
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 18
• Boron Modelling:
Underprediction (low NBI)
Overprediction (High NBI)
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 18
• Boron Modelling:
Underprediction (low NBI)
Overprediction (High NBI)
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 18
• Boron modelling:
Underprediction (2.5 MW NBI)
Overprediction (7.5 MW NBI)
• Helium modelling:
Higher underprediction for all
range of NBI
Opposite trends (EXP / TH)
with ν* (low ECRH)
Modelling vs Experiment
Light impurity transport in AUG and JET P. Manas / ITPA 16th 19
• Comparison between low
ECRH AUG shots and JET
for boron and carbon
• EXP dependencies not
recovered theoritically
• High u’ in JET → Hollow
profiles
• Overall predictions:
Peaked profiles R/LnZ ~ 1
Tests performed so far
• Impact of sub-dominant modes
Nonlinear simulations (including ExB shearing)
• Global effects (symmetry breaking)
Nonzero radial wave number
• Higher poloidal wave numbers contributions
Extension of the QL rule to TEM / ETG range (check consistency with
EXP Qe/Qi)
• Neoclassical transport negligible (NEO)
• Variations of input parameters
• Modifications of the quasilinear rule
Light impurity transport in AUG and JET P. Manas / ITPA 16th 20
Conclusions
• EXP:
Very hollow C compared to Peaked / flat B at similar R/Ln
Higher u’ and R/Lti in JET
• Modelling
JET: overall overprediction of R/LnC
Only cases at high u’ yield very hollow profiles
ASDEX: underperdiction (NBI 2.5 MW), overprediction (NBI 7.5 MW)
for B
• Impact of roto-diffusion:
JET: comparable to thermo-diffusion
AUG: ~20% of thermo-diffusion
• Stronger thermo-diffusion for He but also stronger
disagreement between EXP / modelling
Light impurity transport in AUG and JET P. Manas / ITPA 16th 21
Conclusions
• Missing ingredient?
• Features
Stronger for lower Z impurities
Not dominantly dependent on u’ and R/Lti
Correlation with NBI (clear in AUG, less in JET)
Te/Ti
ν*
???
Hollowness also observed in LHD for C at high NBI (“impurity hole”)
Light impurity transport in AUG and JET P. Manas / ITPA 16th 22