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Impurity transport analysis & preparation of W injection ex-
periments on KSTARFebruary 18, 2014
Joohwan Hong*, Seung Hun Lee, H. Y. Lee, Juhyeok Jang, Juhyung Kim, Siwon Jang, Taemin Jeon ,Jae Sun Park
and Wonho Choe**Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
C. R. Seon, Suk-ho Hong, and KSTAR teamNational Fusion Research Institute (NFRI), Daejeon, Korea
S. Henderson, M. O’Mullane
University of Strathclyde, UK*[email protected]
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Outline1. Introduction
- Current issues on W in tokamak plasmas
2. Current analysis tools for impurity transport study on KSTAR - ADAS-SANCO impurity code analysis
- Diagnostics: SXR and VUV
- Example : ECH effects on Ar transport experiments
3. Preparation of W experiments - Upgrading diagnostics : SXR and VUV
- Estimation of Ar & W emission power on KSTAR for designing SXR
filters
4. Summary & Discussions
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W injection experiments on KSTAR (superconducting machine)
• Influence of W divertor on the access to the H-mode• Effect of W divertor on pedestal parameters and plasma confinement• Predicted impacts of wall and divertor material on pedestal structure• High radiation loss from W core accumulation
R. Neu, ADAS Workshop, 2007, Ringberg
Current issues on W in tokamak plasmas
• ITPA: “Transport of high Z impurities (including W) in the core plasma and possibilities for its control”
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Current analysis tools for impurity transport study
on KSTAR - Focused on Ar injection experiments
• Transport codes (ADAS-SANCO)• Diagnostics (SXR & VUV)• Experiments & analysis results
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SANCO (collaboration with JET) 1D radial continuity equation
- Radial particle flux
Impurity transport analysis : impurity ion density : particle flux via magnetic surface : source and sink (ionization & recombination from ADAS)
𝜕𝑛𝑧 (𝑟 , 𝑡 )𝜕𝑡 =−𝛻 ∙ Γ 𝑧 (𝑟 , 𝑡 )+𝑆𝑧(𝑟 ,𝑡)
Γ 𝑧 (r ,t )=−𝐃(𝐫 )𝜕 (𝑛𝑧 (𝑟 ,𝑡 ) )
𝜕𝑟 +𝑽 (𝒓 )𝑛𝑧 (𝑟 ,𝑡 )
Diffusion coefficient Convection coefficient
- Impurity transport code SANCO
- Fitting analysis codeUTC
KSTAR diagnostics- Soft X-ray array- VUV spectrometer - X-ray imaging crystal
spectrometer, etc…
Impurity trans-port modellingExperimental
data
D, Vdetermination
Fitting
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Soft X-ray arrays with Ar Ross filter
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
HD arrays (33-64)
HU arrays (1-32)16 ch (32)
16 ch (32)
X-ray Ross Filter (XRF)– NaCl and CaF2 – Band pass filter within the narrow region between their L III or K absorption edges
KSTAR D-port
2.8-4.0 keV
• Ar13+, Ar14+, Ar15+, mainly Ar16+, Ar17+
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𝑨𝒓 𝒓𝒂𝒅𝒊𝒂𝒕𝒊𝒐𝒏𝒑𝒐𝒘𝒆𝒓 (𝑾 /𝒄𝒎𝟑)=∑𝑧=0
17
[𝑛𝑒 (𝑟 ,𝑡 )¿{𝑛𝑧 (𝑟 , 𝑡)𝑃𝐿𝑇 (𝑇𝑒 ,𝑛𝑒)+𝑛𝑧 +1(𝑟 ,𝑡)𝑃𝑅𝐵 (𝑇 𝑒 ,𝑛𝑒)}]¿
Model for Ar emission in soft X-ray range
Power coeffs of Line Transition Power coeffs of RecomBination
(2) Response function of Ross filter
(1) Calculation of local Ar radiation power (r,t)
Obtaining 2.8~4 keV
(3) LoS calculation and line integration
- ne from input data, nz from SANCO, PLT & PRB from ADAS
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ITER VUV spectrometer prototypeCurrent (15-60 nm, ~13-40 ms)
Vacuum extension
VUV spectrometer on the optical table
Collaboration with ITER KO-DA (C.R. Seon)
1 ch, survey He I 53.70 nmHe II 25.63 nmO V : 15.61, 19.28, 21.50 nmO VI : 17.30, 18.40 nmC III : 38.62 nmC IV : 24.49, 38.41, 41.96 nmC V : 22.72, 24.87 nmFe XV : 28.42 nmFe XVI : 33.54, 36.08 nmAr XIV 18.79 nmAr XV 22.11 nmAr XVI 35.39 nm
- All atomic coefficients are from ADAS
𝑨𝒓 +𝒛𝒑𝒉𝒐𝒕𝒐𝒏𝒆𝒎𝒊𝒔𝒔𝒊𝒗𝒊𝒕𝒚=𝑛𝑧 (𝑟 , 𝑡 )𝑛𝑒 (𝑟 , 𝑡 ) 𝑃𝐸𝐶(𝑇𝑒 ,𝑛𝑒)(2) Modeling of Ar line transitions
(1) Measurable major line transitions
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L-mode plasmas, Ip = 400 kA, Bt : 2 T
Argon gas injection through a piezo valve (trace amount of Ar : nAr/ne < 0.1%)
Different transport w/o and w/ ECH positions Feasibility of impurity control?
On-axis ECH
Ar
0.4
0.2
0 1 2 3 4 Time (sec)
Ip (M
A)
Ar puffing20 ms
0.4
0.2
0 1 2 3 4 Time (sec)
Ip (M
A)
Ar puffing20 ms
ECH110 GHz300 kW
Non ECH On-axis ECH
Ar puffing after ECH start To see ECH effect on Ar
Ar transport experiments with ECH
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SXR emissivity(Non ECH)
SXR emissivity(On-axis ECH)
VUV Ar15+
Time (s)
Cha
nnel
#
2 2.2 2.4 2.6 2.8 3
5
10
15
Time (s)
Cha
nnel
#
2 2.2 2.4 2.6 2.8 3
5
10
15
t
• 2.8 – 4 keV photons• Mainly Ar16+ & Ar17+
emissions
ECH
r
r
Less core Ar emissivity with ECH
Ar puffNon-ECH
ECH
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0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a
0 0.2 0.4 0.6 0.8 1-15
-10
-5
0
Con
vect
ion
(m/s
)
r/a
0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a
0 0.2 0.4 0.6 0.8 1-15
-10
-5
0
5
Con
vect
ion
(m/s
)
r/a
Ch1
Ch16
ConvectionDiffusion
0
20
40
60
80
Emis
sion
pow
er (W
/m2 )
Ch 3 (r/a =0.5)
ExperimentSANCO
Ch 4 (r/a =0.42) Ch 5 (r/a =0.35)
2 2.05 2.1 2.15 2.2 2.250
20
40
60
80
Emis
sion
pow
er (W
/m2 )
Time (s)
Ch 6 (r/a =0.26)
2 2.05 2.1 2.15 2.2 2.25Time (s)
Ch 7 (r/a =0.18)
2 2.05 2.1 2.15 2.2 2.25Time (s)
Ch 8 (r/a =0.08)
ADAS-SANCO analysis results
L-modeNon-ECH
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Ch1
Ch16
ConvectionDiffusion
L-modeOn-axis ECH
0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a
0 0.2 0.4 0.6 0.8 1-15
-10
-5
0
Con
vect
ion
(m/s
)
r/a
0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a
0 0.2 0.4 0.6 0.8 1-15
-10
-5
0
5
Con
vect
ion
(m/s
)
r/a
0
10
20
30
40
50
Emis
sion
pow
er (W
/m2 ) Ch 3 (r/a =0.5)
ExperimentSANCO
Ch 4 (r/a =0.42) Ch 5 (r/a =0.35)
2 2.05 2.1 2.15 2.2 2.250
20
40
Emis
sion
pow
er (W
/m2 )
Time (s)
Ch 6 (r/a =0.26)
2 2.05 2.1 2.15 2.2 2.25Time (s)
Ch 7 (r/a =0.18)
2 2.05 2.1 2.15 2.2 2.25Time (s)
Ch 8 (r/a =0.08)
Diffusion & convection with ECH
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Preparation of W experiments
- Upgrading current diagnostics (VUV & SXR)- Estimation of W & Ar emission power on KSTAR for de-
signing filters of new SXR system
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VUV imaging spectrometerThis summer(5-20 nm, 13-130 ms)
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.0228 ch, imaging
Collaboration with ITER KO-DA (C.R. Seon)
25.4 nm He II from Hollow Cathode Lamp
~5.5 mm Slit Imaged to CCD Slit Pattern Spacing ~ 2mm
5~7 nm quasi-continuum peaks of W are expected
24.6 nm 23.4 nm
Preparation in laboratory
• Active pixels: 1024 x 256 • Pixel size (W x H): 26 x 26 μm • Image area: 40 mm x 12mm of MCP adopted to CCD of 27.6
Clementson et al. Rev. Sci. Instrum. 81, 10E326 2010
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4 arrays, 256 ch
• 4 arrays, 256 chs 2D Tomography Poloidal asym. study• < 2 cm, 2 μs
1 array, 48 ch
• 3 filters• multi energy, neural network• < 1.3 cm, 2 μs
HU
HD
VD2
VU2
Soft X-ray array systemThis summerCurrent
0.004
0.006
0.008
0.01
0.012
0.014
0.016
0.018
0.02
HD arrays (33-64)
HU arrays (1-32)16 ch (32)
16 ch (32)
2 arrays, 64ch
• Be filters (10, 50 um)• Ar Ross filters (2.8-4.0 keV Ar16+, Ar17+)• Bolometer (No filter) 2D fast MHD & transport study
edge
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• For designing new multi-array SXR filter to measure W & Ar emission, ADAS-SANCO simulation has been done
Estimation of W & Ar emission power
EFIT
Background (Te, ne)
D, V(Trial value)
Impurity Influx
Input
SANCO
nz(r, t)
ADASCalculates line emission for every line transition
Te, ne
Line integration along LOS Final power spectrum of W & Ar
Calculates…- nz(r, t) for every charge states z of W & Ar
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(1) Te & ne profiles of typical KSTAR L-mode and H-mode - Evaluated by ECE, TS, interferometer.
(3) EFIT
#7566 @ 2 sBy S. Sabbagh
(2) Influx : flow meter signal for both W & Ar
Input profiles for ADAS-SANCO
Recycling rate• Ar = 0.6• W = 0.0
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2
2.5
3
3.5
4
r/a
n e [ 1
019 m
-3 ]
L-modeH-mode
0 0.2 0.4 0.6 0.8 10
0.5
1
1.5
2
2.5
3
3.5
4
4.5
r/a
T e [keV
]
L-modeH-mode
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- D & V for L mode (experimentally obtained from KSTAR #7574 Ar)
- D & V for H mode (from ASDEX-U results)
T. Putterich, 2005, ‘Investigations on Spectroscopic Diagnostic of High-Z Elements in Fusion Plasmas’ , PhD Thesis University Augsburg
0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5D
iffus
ion
(m2/s
)
r/a0 0.2 0.4 0.6 0.8 1
-15
-10
-5
0
5
Con
vect
ion
(m/s
)
r/a
Input profiles for ADAS-SANCO
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Time evolution of line-integrated spectra(1) L-mode
(2) H-mode
ArW
Ar W
Photon energy (keV) Time (s)
Bri
ghtn
ess (
W c
m-2 )
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0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)
W/c
m3 e
V
L-mode case H-mode case
W & Ar emission spectrum under KSTAR condition
0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)W
/cm
3 eV
W peaks
Ar peaks(Ross filter)
W peaksW quasi-continuum(VUV)
where
with C dominant situation
• Continuum radiation was calculated by
S. von Goeler et al., Nucl. Fusion 15, 301 (1975)
Zeff ~ 2.5
Ar peaks(Ross filter)
W c
m-2 e
V-1
W c
m-2 e
V-1
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Summary
Impurity transport analysis tools on KSTAR - ADAS-SANCO impurity transport code
- Soft X-ray array system and VUV spectrometer system
- It has well worked for KSTAR Ar injection experiments since 2012.
W injection experiment is under preparation on KSTAR - Imaging VUV spectrometer having W quasi-continuum peaks is installed on
KSTAR F-port.
- Additional SXR arrays will be installed on KSTAR D-port with Be filters for W
and Ar measurement.
- ADAS database set is also ready for simulating W emissions in fusion plasmas.
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0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)
W/c
m3 e
V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Filte
r tr
ansm
issi
on
Discussions(1) SXRA filter design for discriminating W and Ar emission
Delgado-Aparicio et al., Nucl. Fusion 49, (2009) 085028
50 m
100 m
250 m
300 m
400 m
Be filters of
L-mode case
W c
m-2 e
V-1
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Discussions(1) SXRA filter design for discriminating W and Ar emission
Be 50 & 250 m seem to be appropriate for L- & H- modes.
0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)
W/c
m3 e
V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Filte
r tr
ansm
issi
on
50 m
100 m
250 m
300 m
400 m
H-mode case
W c
m-2 e
V-1
0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)
W/c
m3 e
V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Filte
r tr
ansm
issi
on
50 m
100 m
250 m
300 m
400 m
Be filters of
L-mode case
W c
m-2 e
V-1
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• Estimated value ~ 6 X 1016 atoms (~ 18 g) Too small!• Particles should be injected more, in order to obtain the same Ar emission
level, since all particles can not penetrate into LCFS.
Calculated Brightness filtered by 50 m (in W/cm2)• Brightness from Continuum = 1.10 X 10-1
• Brightness from Ar emission = 1.12 X 10-1
• Brightness from W emission = 5.52 X 10-1
W emission level is larger than Ar by 5
Injected W should be reduced by 5 ?
Estimation conditions - Injected # of atoms = 3.0 x 1017 for W & Ar- Find out amount of W providing similar Ar radiation level ( W/cm2 , > noise level of
AXUV = 0.001 W/cm2) which was tested in previous Ar injection experiments.
(2) Estimation of amount of W injection
Discussions
0 0.5 1 1.5 2 2.5 3 3.5 4 4.510
-6
10-5
10-4
10-3
X-ray energy (keV)
W/c
m3 e
V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Filte
r tr
ansm
issi
on
50 m
W c
m-2 e
V-1
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Discussions
(3) W injector for KSTAR - Gun-type injection system is under development
- Please see the other presentation material for W gun…
(4) Expected studies - Z-dependence study of impurity transport with double injection (Ar & W)
- ECH power scan as well as other auxiliary heating (ICRH, LH) to control
W & Ar impurities.
- Magnetic perturbation effects on impurity transport
- Asymmetric formation of impurity concentration with full 2-D tomography
by new SXR system
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1. Z-dependence study of impurity transport - Simultaneous injection of Ar & W for the 2014 campaign
- Various turbulent-based transport theories have been trying to estimate impurity transport with varying Z. Nevertheless, there is no theory explaining experimental results well.
- It is required to have more experimental data to develop and revise impu-rity transport models.
H Nordman et al, 2011 Plasma Phys. Control. FusionGiroud C. et al 13th ITPA Confinement Database & Modelling Topical Group, Naka, Japanne /<ne>0.8 1.0 1.2 1.4
1.0
0.0
0.5
1.5
2.0
Closed symbol: [Dmeas, Vmeas]Open symbol: [Dmeas, Vneo]
0
Expected studies
JETresult
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- Controllability of Ar impurity was confirmed by ECH on KSTAR.- Applying ICRH, ECCD as well.- Effects on not only Ar but also W.
2. Control impurity transport by applying auxiliary power
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.5
1
1.5
2
2.5
3
3.5
4
4.5x 10
16#/
m3
r/a
No ECH
Total ArAr+16
Ar+17
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
2
4
6
8
10
12
14
16
18x 10
15
#/m3
r/a
On-axis ECH
Total ArAr+16
Ar+17
3. Effects of RMP on impurity transport - Find out the relationship and mechanism between magnetic perturbation
and impurity transport from edge (ELM) to core (impurity accumulation).
- Applying MP after injection and before injection.
Expected studies
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Expected studies
M Reinke, et al., E1/E2 Task force meeting 2012
4. Impurity formation of poloidal asymmetryICRH L-modeH-mode
C-Mod, Mo injection
- Full 2-D tomography reconstruction will be available with vertical arrays
Finding poloidal asymmetry of high-Z impurities such as W Comparing between Ar & W cases
- For various plasma modes and conditions
C-ModMo injection
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Appendix
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UTC-SANCO analysis
Nn
nnn yfw,1
22
UTC (Universal Transport Code)
calculate 2
Nonlinear least square fit(Levenberg-Marquardt Method)
Proper?
GetD, V
No Yes
: Error range factor : Simulated data : Measured data
Parame-terize Co-
effsD, V or In-
flux
Set proper derivative to param-
eters
Find new solution which
minimize 2
Geometry
Back-ground (Te, Ti, Ne)
D, V(Trial value)
Impurity In-flux
In-put Ar emission
diagnostic data
SANCO Ar emission
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Ar transport control experiments using
ECH on KSTAR
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L-mode plasmas, Ip = 400 kA, Bt : 2 T Argon gas injection through a piezo valve (trace amount of Ar : nAr/ne < 0.1%) Different transport with varying ECH positions Feasibility of impurity control?
Heating position(r/a = 0, 0.16, 0.30, 0.59)
On-axisAr
0.4
0.2
0 1 2 3 4 Time (sec)
Ip (M
A)
Ar puffing20 ms
#756
6 0.4
0.2
0 1 2 3 4 Time (sec)
Ip (M
A)
Ar puffing20 ms
#757
4
ECH110 GHz300 kW
No ECH On-axis ECH
Ar puffing after ECH start To see ECH effect on Ar
Ar transport experiments with ECH
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Ar transport experiments with ECH Argon gas injection through a piezo valve (trace amount of Ar : nAr/ne < 0.1%) Different transport with varying ECH positions Feasibility of impurity control?
Heating positions(r/a = 0, 0.16, 0.30, 0.59)
40 cm2010 Ar
Using 110 GHz ECH system
ECHLauncher
N portIp
Bt
x
y
R=1.8m
~ 50°
- Target: R0 = 1.8 m (B0=1.964T), Tor = -5. deg.- ECH power was fixed : 350 kW- Heating position changed by tilting the lanching mirror
On-axis
Mi Joung, EC17, May 7-10, Deurne, Netherlands, 2012
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SXR emissivity(No ECH)
SXR emissivity(On-axis ECH)
VUV Ar15+
Time (s)
Cha
nnel
#
2 2.2 2.4 2.6 2.8 3
5
10
15
Time (s)
Cha
nnel
#
2 2.2 2.4 2.6 2.8 3
5
10
15
t
• 2.8 – 4 keV photons• Mainly Ar16+ & Ar17+
emissions
ECH
r
r
Less core Ar emissivity with ECH
Ar puffNo-ECH
ECH
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Most effective (i.e., least core impurity concentration) with on-axis ECHLess effective with ECH heating position at larger radius
Time (s)
Cha
nnel
#
1.5 2 2.5 3 3.5
No ECH
On-axis
r/a = 0.16
r/a = 0.30
r/a = 0.59
r
r
1.5 2 2.5 3-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Time (s)
P SXR
, nor
m. c
h #8
[A. U
]
No ECHOn-axis ECHECH @ r/a = 0.16ECH @ r/a = 0.30ECH @ r/a = 0.59
Less core Ar emissivity with ECH
On-axis ECH
0.16
0.30, 0.59
No ECH Core ch #8
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2-D Reconstructed Ar emissivity• Core-focused reconstruction (Cormack algorithm)• Emissivity images of mainly Ar16+ & Ar17+ impurities
No ECH On-axis ECH
1.41.6
1.82
2.2
-0.5
0
0.5
0
0.05
0.1
0.15
0.2
0.25
R (m)Z (m)
PSX
R (k
W/m
3 )
1.4 1.6 1.8 2 2.20
0.05
0.1
0.15
0.2
R (m)
I SXR (
kW/m
3 )
0.01
0.02
0.03
P SXR (
kW/m
3 )
SXR004
0.02
0.04
0.06
0.08
P SXR (
kW/m
3 )
SXR007
0.02
0.04
0.06
0.08
P SXR (
kW/m
3 )
SXR010
0.01
0.02
0.03P SX
R (kW
/m3 )
SXR019
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
0.02
0.04
0.06
0.08
Time (s)
P SXR (
kW/m
3 )
SXR024
Shot #7566, Time: 2.230000 s
1.4 1.6 1.8 2 2.20
0.05
0.1
0.15
0.2
R (m)
I SXR [k
W
m-3
]
0.01
0.02
0.03
P SXR (k
W/m
3 )
SXR004
0.02
0.03
0.04
0.05
P SXR (k
W/m
3 )
SXR007
0.01
0.02
0.03
0.04
0.05
P SXR (k
W/m
3 )
SXR010
0.01
0.02
0.03
0.04
P SXR (k
W/m
3 )
SXR019
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
0.02
0.03
0.04
0.05
0.06
Time (s)
P SXR (k
W/m
3 )
SXR024
Shot #7574, Time: 2.220000 s
1.31.55
1.82.05
2.3
-0.5-0.25
00.25
0.50
50
100
150
200
R [m]Z [m]
P SXR
[W
m-3
]
Z R Z R
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0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5D
iffus
ion
(m2 /s
)
r/a0 0.2 0.4 0.6 0.8 1
-15
-10
-5
0
Con
vect
ion
(m/s
)
r/a
0 0.2 0.4 0.6 0.8 10.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a0 0.2 0.4 0.6 0.8 1
-15
-10
-5
0
5
Con
vect
ion
(m/s
)
r/a• With on-axis ECH, central (r/a = 0 ~ 0.3) diffusion and convection are increased.• For convection, the sign is reversed from – to +: Inward Outward pinch
#7566: No ECH
#7574: On-axis ECH
Outward
Modification of D & V by ECH
Inward
Inward
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Effect on central impurity accumulation ◈ Radial distribution of total Ar density versus time by SANCO
Total Ar
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.5
1
1.5
2
2.5
3
3.5
4
4.5x 10
16
#/m3
r/a
No ECH
Total ArAr+16
Ar+17
Tim
e (s
)
r/a
No ECH
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.82.05
2.1
2.15
2.2
2.25
2.3
0.5
1
1.5
2
2.5
3
3.5
4x 10
16No ECH (#7566)
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
2
4
6
8
10
12
14
16
18x 10
15
#/m3
r/a
On-axis ECH
Total ArAr+16
Ar+17
Tim
e (s
)
r/a
On-axis ECH
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.82.05
2.1
2.15
2.2
2.25
2.3
2
4
6
8
10
12
14
16
x 1015On-axis ECH (#7574)
Hollow profilePeaked profile
Tim
e
r/a
Tim
e
r/a
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Neoclassical contribution of Ar transport
No ECH (#7566)
On-axisECH
(#7574)
D, V by NLCASS is smaller by an order of magnitude than the experimental D, V. The impurity transport is anomalous, rather than neoclassical.
Neoclassical calculation of D and V was done by NCLASS
0 0.1 0.2 0.3 0.4 0.50
0.1
0.2
0.3
0.4
0.5D
iffus
ion
(m2 /s
)
r/a
0 0.1 0.2 0.3 0.4 0.5-15
-10
-5
0
5
Con
vect
ion
(m/s
)
r/a
0 0.1 0.2 0.3 0.4 0.50
0.1
0.2
0.3
0.4
0.5
Diff
usio
n (m
2 /s)
r/a
0 0.1 0.2 0.3 0.4 0.5-15
-10
-5
0
5
Con
vect
ion
(m/s
)r/a
0 0.1 0.2 0.3 0.4 0.57
8
9
10x 10
-3
Diff
usio
n (m
2 /s)
r/a
0 0.1 0.2 0.3 0.4 0.5-0.1
-0.05
0
0.05
0.1
0.15
Con
vect
ion
(m/s
)
r/a
NCLASS10*NCLASS
Exp
10*NCLASS
ExpNCLASS
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Possible mechanism of impurity pinchFrom quasi-linear calculation of Weiland multi-fluid model 3 impurity pinch terms[1, 2]
Pinch type Description Pinch directionby turbulence type
Curvature pinch Compressibility of ExB drift velocity Inward
Thermodiffusion pinch
Compression of the diamagnetic drift velocity ITG OutwardTEM Inward
Parallel impurity compression
Parallel compression of parallel v fluctuations produced along the field line by fluctuating electrostatic potential
ITG InwardTEM Outward
[1] H. Nordman et al., 2011 Plasma Phys. Control. Fusion 53 105005
Curvature pinch
Thermodiffusion pinch
Parallel compression
pinch
Is the outward convection of Ar due to ITG or TEM?[2] Giroud C. et al 13th ITPA Confinement Database & Modelling Topical Group, Naka, Japan