6 Euratom/CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK. 7 Max-PLanck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM Assoziation, ...
ITPA SOL & Divertor
Multitokamak scaling for prediction of ITER SOL width in HFSlimited startup plasma (Following and concluding from ITPA meeting Oct. 2012)
J. Horacek1, R.A. Pitts2, J. Gunn3, C. Silva4, D. Rudakov5, G. Arnoux6, S. Marsen7, P. Vondracek1,8, G. Maddaluno9, V. Pericoli9, B. Viola9, G. S. Xu10, H. Wang10, M. Shimada2, J. Adamek1, Tsv. Popov11, M. Dimitrova1, R. Goldston12, P.C. Stangeby13, F. Janky1, J. Havlicek1, J. Seidl1, R. Dejarnac1, R. Panek1, P. Dobias14 and the JET-EFDA contributors6 1 Association EURATOM-IPP.CR, Institute of Plasma Physics AS CR, Za Slovankou 3, 18221 Praha 8, Czech Republic 2 ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance, France 3 CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France 4 Associação EURATOM/IST, Instituto de PLasmas e Fusão Nuclear, IST, Av Rovisco Pais, 1049-001 Lisbon, Portugal 5 General Atomics, PO Box 85608, San Diego, CA 92186-5608, USA 6 Euratom/CCFE, Culham Science Centre, Abingdon, OX14 3DB, UK 7 Max-PLanck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM Assoziation, 17491 Greifswald, Germany 8 Faculty of Math and Physics, Charles University, Czech Republic 9 ENEA-UT Fusione, Centro Ricerche Frascati, Italy 10 Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China 11 Faculty of Physics, St. Kliment Ohridski University of Sofia, J. Bourchier Blvd., 1164 Sofia, Bulgaria 12 Princeton, Plasma Physics Laboratory, Princeton NJ 08543, USA 13 University of Toronto, Institute for Aerospace Studies, Toronto, M3H 5T6, Canada
th J. This Horacek for ITPA-Div/SOL group by1/13 18P205/12/2327 ITPA/DSOL, and Hefei, ChinaProject 20.3.2013 research was partly supported GA CR MSMT # LM2011021
ITPA SOL & Divertor
Motivation Toroi d
Goal: To predict heat flux spatial distribution on the ITER HFS wall during its startup limiter phase.
al x
λq determines optimal shape of the HFS Beryllium tiles. toroidal
Note: there is no theory-based model with credible predictive capability!
ITER ITER physics basis, Nuclear Fusion 39 2391 (1999)
Derived for diverted plasma at divertor. Is this scaling correct for limiter? No: [Saoutic Nucl.Fus. 2011], [J. Gunn, PSI 2012]
TS : Valid for others than Tore Supra? J. Horacek for ITPA-Div/SOL group
2/13
18th ITPA/DSOL, Hefei, China
20.3.2013
Database overview 264 radial profiles (q)
ITPA SOL & Divertor
ITER
JET
Tore Supra
DIII-D
EAST
FTU
R [m]
6.0
2.8
2.2
1.7
1.85
a [m]
2.0
0.98
0.65
0.6
0.46
Ip [kA]
35007500
1500 | 2500
4001200
6001200
B [T]
5.3
2.8
2.64.1
1.9
1.96
Instrument for Te
-
Swept Langmuir
Tunnel probe
Harmonic
Triple probe
Isotope
H, D, He, T
D
D
D
D
J. Horacek for ITPA-Div/SOL group
3/13
TCV
COMPASS
CASTOR
0.935
0.85
0.55
0.4
0.28
0.3
0.2
0.065
300 250-500
260
80-180
9
2.7-7.5
1.2
1.1
1.3
Swept Langmuir or ball-pen
Swept Langmuir
H/D
H
Limiter double-null
Swept Swept Langmuir Langmuir
D
D
18th ITPA/DSOL, Hefei, China
20.3.2013
(Bottom contact)
ITPA SOL & Divertor
Analysis procedure (1/2) COMPASS 59
TCV
1. Perform plasma limited at HFS 2. Measure q, mapped to
EAST 2
outboard midplane, using reciprocating probe (IR
14
2
camera)
3. q~f(R0,B0,Ip,P,...)
33 DIII-D
4. predict qITER
23
1 representative profile
FTU: 9
13
JET
121
Tore Supra
3cm gap
CASTOR
J. Horacek for ITPA-Div/SOL group
4/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
Reciprocating probes 1. Obtain Te & Jsat by ● Single probe: ● Classical fit IV-characteristics ● Harmonic technique ● Tunnel probe ● Three probes: ● Isat, Te=(BPP -LP )/2.2 fl fl Triple probe 2. Te±Te & Jsat±Jsat =>q||=JsatTe ●
3. plot & fit q||=q0exp(-romp/q) mapped to outer midplane => get one qomp value per reciprocation Note that q-1=Isat-1+Te-1 ≈ Isat-1 ≈ ne-1 => the Te-technique not too important
CASTOR & FTU is different: q reason for q FTU always shorter than COMPASS? J. Horacek for ITPA-Div/SOL group
5/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
Analysis procedure (2/2)
4. Searching for most credible scaling of q with 18 parameters: –
LCFS or Dimensionless (understandable scaling but uncertain for ITER):
• TeLCFS, neLCFS, LCFS, *LCFS, • Example: we expect [Garcia, PPCF (2007) B47] s ~ Lc*vrblobs (*,
LCFS) / cs|| (Ti).
– Engineering (well known for ITER => lower error): • P [W/m3] , Ip[MA/m2], new PSOL/ALCFS, B0, R0, a/R0 omp • less acurate: Lc, n, n/nGW, new Bpol ( no predictive capability. Therefore, parameters used in the credible scalings must satisfy – low mutual correlations, let's say |Exponent| > 1/4, otherwise not credible => usually removing n, n/nGW This still yields dozens of reasonable scalings … however ...
J. Horacek for ITPA-Div/SOL group
12/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
5 most credible scalings ... yield similar qITER ☺
High exponents in anticorrelated parameters =>overfit
J. Horacek for ITPA-Div/SOL group
13/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
Conclusion on ITER scenario
λqomp
2.5MA
5.0MA
73
49
44
83±18
60±11
52±7
Most credible λq[mm]=
7.5MA
overfit
=5100(Ptot/V)-0.37(a/R)0.77κ-1.1 Mean of 12 most credible scalings λq[mm]
λqomp is the SOL decay length mapped to outer midplane. Identified dozens of more-or-less reasonable scalings, yielding similar ITER values. Let ITER staff decide which scaling (= parameter combination) to believe most The actual ITER design assumes HFS IMP q=50mm for 7.5MA … which is pretty close :-)
Warnings: – Based only on probes. – On JET: qIR not well correlated (because small plasma variation) with qRCP, however, power balance OK.
– Valid only in the far SOL! – Both JET & COMPASS IR camera shows qperp>q||sin() in the near SOL (r Theodor
EFIT EFIT mapping angle
Surface temperature
Assuming qlim(r,)=q0exp(-rmid/qcos()+qfunneling(rmid) J. Horacek for ITPA-Div/SOL group
16/13
18th ITPA/DSOL, Hefei, China
G. Arnoux et al. IAEA FEC 2012, EX/P5-37 20.3.2013
ITPA SOL & Divertor
Correlations with q: DIIID no dependence (all C forget ASDEX Upgrade for the SOL scaling? J. Horacek for ITPA-Div/SOL group
29/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
Inner wall x outer wall limited plasmas
C. Silva, …, J. Horacek, et al. PSI conference 2012, J. Nucl. Mat. J. Horacek for ITPA-Div/SOL group
30/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
LFS
J. Horacek for ITPA-Div/SOL group
31/13
18th ITPA/DSOL, Hefei, China
20.3.2013
ITPA SOL & Divertor
Tokamak CASTOR
R=0.4m, a=0.085m, B=1.3 T, ne
