elm energy/particle plasma losses and fluxes on pfcs · physics of elm instability and experimental...
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A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 1
ELM Energy/Particle Plasma Losses and Fluxes on PFCs
Alberto LoarteEuropean Fusion Development Agreement
Close Support Unit - Garching
Contributions from : G. Saibene, R. Sartori, T. Eich, M. Kempenaars, M. Becoulet, G. Federici, P. Snyder, P. Ghendrih, G. Huysmans, C. Pérez, R. Koslowki, I. Nunes,B. Gonçalves, C. Silva, W. Fundamenski, T. Petrie, A. Leonard, M. Fenstermacher,J. Boedo, J. Stober, N. Oyama, Y. Kamada, N. Asakura, G. Counsell, A. Kirk,S. Saarelma, J Lönnroth, V. Parail, �..
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 2
Outline of the Talk
1. Introduction
2. Physics of ELM instability and experimental evidence
3. Main plasma ELM energy/particle losses
4. ELM energy/particle fluxes to PFCs
5. Regimes with high Pped + small/no ELMs
6. Conclusions
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 3
Introduction (I)H ~ 1 at n ~ nGW in Type I ELMy H-modes requires high Wped
0.4 0.6 0.8 1.00.0
0.2
0.4
0.6
Open symbols Type III ELMs
Wpe
d/Wdi
anped/nGW
DOC-L 1.2MA/1.2TDOC-L 1.2MA/1.2TDOC-L 2.0MA/1.8TDOC-L 2.0MA/2.4TDOC-L 2.0MA/2.4T DOC-L 2.0MA/3.0TDOC-L 3.0MA/3.0TDOC-U 2.0MA/2.4T
PINP = 12MWDOC-U 2.0MA/2.4T
PINP = 12MWDOC-U 2.0MA/2.4T
PINP = 17MWDOC-U 2.0MA/2.4T
PINP = 17MWDOC-U 2.5MA/2.7THT3 1.1MA/1.2THT3 2MA/2.2THT3 2MA/3.2THT3 2.5MA/2.3THT3 2.5MA/2.7THT3 2.5MA/2.7THT3 2.5MA/3.4THT3 2.5MA/3.4THT3 3MA/2.7THLT 3MA/2.5T
! weak Wped/Wdia dependence on :q95 (2.8 < q95 < 5.2), Pinp , δ (δ > 0.27)
! lower Wped/Wdia @ low Ip & Type III ELMs
Wped/Wdia (JET-Type I ELMs) ~ 0. 4 ± 0.1
JET-Loarte APS�03
JET-Saibene EPS�03
general result for Type I ELMyH-modes (ASDEX-U, DIII-D, JET, �)
ITER
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 4
Introduction (II)Pedestal plasma experiences quasi-periodic relaxations " ELMs
∆WELM small fraction of Wplasma (<10 %) to divertor/wall in ~ 200 µs " Large Energy Flux
JET � Type I ELM - Saibene Only Pedestal Region of Plasma Affected by ELMs
JET � Type I ELM - Saibene
Main Plasma
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 5
Introduction (III)ITER rough estimates
Wdia = 350 MJ " Wped = 90 � 150 MJ, ∆WELM = 10 - 30 MJ(Adiv = 3 m2, τELM= 300 µs)
TmaxELM > Tev,melt
C,W " ELM Erosion
~ 3.5 µm/ELM + C-target = 2 cm " 6000 ELMs !!ΦELMC,W(MJm-2s-1/2 ) ≤ 50 for small ELM erosion
ITER-Federici PPCF�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 6
Physics of ELM instability (I)Peeling-Ballooning model of the ELMs (Connor PPCF�98)
(a) ballooning: n=20
α↑↑↑↑ jedge↓↓↓↓
1.0.9
(b) peeling: n=3
1.0.9√ψ
α↓↓↓↓ jedge↑↑↑↑ α↑↑↑↑ jedge↑↑↑↑
√ψ
(c) ballooning-peeling: n=12
1.0.9√ψ
0.8
JET-Huysmans �01
! Ballooning modes driven by grad Pped! Kink (peeling) modes driven by edge current (large Jbootstrap)! Coupled peeling-ballooning modes
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 7
Physics of ELM instability (II)Peeling-Ballooning calculations-experiment comparison
DIII-D-Snyder NF�04
! Pped matched with model! Change of mode instability analysed! Role of jbootstrap evaluated (+ measured)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 8
Physics of ELM instability (III)Role of edge current on ELM triggering demonstrated
JET-Becoulet EPS�03
0.0 1.0 2.0 3.0 4.0 5.0
0.0 1.0 2.0 3.0 4.0 5.0
0.0
1.0
2.0
3.0
4.0
60.5 61.5 62.5 63.5
0.0 2.0 4.0 6.0 8.0
ms
]2
-1χ
[103
iB
Pγ
s]
-1[1
04_
γs
]-1
[104
_I [
10A]
6
t [s]
(a)
(b)
(c)
(d)
0.0 2.0 4.0 6.0 8.0
[10
J]6
Wth
(e)
current
ballooningmodegrowth rate
peeling modegrowth rate
thermal energy content
JET-JETTO-Lönnroth-Parail �04
seen in COMPASS-D, MAST, JET
Ramp-up
Peeling-ballooningPure peeling
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 9
Physics of ELM instability (IV)Scaling of pedestal pressure and peeling-ballooning model
JET-Loarte APS�03
1 2 3 41000
10000
~ Ip2
DOC (δ ~ 0.3) HT3 (δ ~ 0.45)
P ped (
Pa)
Ip (MA)
PpedType I ~ Ip2(ballooning-like)
Pped depends weakly on : q95 and ne,ped/nGWPpedType I ~ Ip
DIII-D-Snyder NF�04
comparison of model with various experiments required to identify physics processes
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 10
Physics of ELM instability (VI)precursors seen before ELMs in manyexperiments with n = 1-10
JET-Pérez NF�04
! precursors� n as expected from P-B
! precursors do not grow as linearly unstable modes et/τ
! role of precursor on ELM trigger is unclear
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 11
Physics of ELM instability (VII)Filaments are seen to appear in the plasma boundary prior to
ELMs (n = 10, q =4)MAST-Akers PPCF�03
how much energy flows in the filaments?
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 12
Physics of ELM instability (VIII)Analyses of energy fluxes far from strike point in ASDEX
Upgrade are consistent with n = 8 � 24 modesASDEX Upgrade-Eich PRL�04
energy content in stripes less than 3% of ∆WELMdiv !!
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 13
Physics of ELM instability (X)ELM spatial and temporal ballooning character
DIII-D-Petrie NF�03 ASDEX Upgrade-Nunes EPS�03 subm. NF�04
similar results on divertor fluxes from ASDEX Upgrade, MAST, JET
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 14
Physics of ELM instability (XI)Timescale of ELM pedestal collapse/MHD phase timescale :
collapse of pedestal - hot e- impact on divertor - MHDJET-Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 15
Physics of ELM instability (XII)Timescale of ELM pedestal collapse ~ 200 - 300 µs for JET Type I ELMs
Similar timescales in JT-60U, DIII-D, ASDEX Upgrade MAST
0.3 0.4 0.5 0.6 0.7 0.80
100
200
300
400
500
1.2MA q95 = 3.12MA q95 = 3.73MA q95 = 3.1
τELM
X-ra
y (µs
)
nped/nGreenwald
0.3 0.4 0.5 0.6 0.7 0.80
100
200
300
400
500
1.2MA q95 = 3.12MA q95 = 3.73MA q95 = 3.1
τELM
MH
D (µ
s)nped/nGreenwald
JET-Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 16
Physics of ELM instability (XIV)Physical mechanisms of ELM growth
! Non-linear explosive ballooning (Cowley PPCF�03)τELM ~ (τE τA
2)1/3
τA ~ qRn1/2/B, τE ?JET : τELM (τE) ~ 50-100 µs but τELM ~ Rα with α ~ 5/3
τELM ~ (Ip-2/3 n1/3) x (P-2/9 n1/6 Ip1/3) ~ Ip �1/18 (if n ~ Ip, P ~Ip) !!!
! Edge Reconnection (Igitkahnov EPS�01)τELM ~ τA(τη/τA)β (β =[1/3,1])
τELM (β=1/2) ~ (R1/2 Ip-1/2 n1/4) x (a1/2 T3/4) ~ R Ip1/2 (if n ~ Ip, T ~Ip)
More experimental and theoretical work is needed!!!
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 17
Physics of ELM instability (XV)
how filaments evolveto an edge plasma collapse ?
MAST-Kirk PPCF�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 18
Main plasma ELM energy/particle losses (I)
ELM energy/particle losses depend on pedestal parameters
ITPA-Loarte PPCF�03
Small ∆WELM/Wped seen at high ne,ped/nGW and/or high ν*ped(neo)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 19
Main plasma ELM energy/particle losses (II)
Simple picture : small ∆WELM #" small volume of plasma affected by ELM
Peeling/Ballooning Picture : increasing nped - ν*ped
n of unstable modes increase #" poloidal width of modes decrease
ELM affected volume (VELM) " ∆WELM decreases
0.0 0.2 0.4 0.60.00
0.05
0.10
0.15
0.20DOC-U 2MA q95 = 3.7 δ = 0.32
∆WEL
M/W
ped
ν*(neo)0.85 0.90 0.95 1.00
0.0
0.2
0.4
0.6
0.8
1.0
Low νped
Medium νpedHigh νped
Mod
e am
plitu
de (a
.u.)
r/a
JET-Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 20
0.6 0.7 0.8 0.90
1000
2000Pulse No. 55973 DOC-U 2MA q95=3.6 δ=0.32
T e(eV
)
r/a
Before ELMAfter ELM
Main plasma ELM energy/particle losses (III)
0.6 0.7 0.8 0.9
0.0
0.2
0.4
0.6
0.8
1.0
DOC-U 2MA q95=3.6 δ=0.32 ∆WELM = 0.28 MJ (low ne) ∆WELM = 0.17 MJ (medium ne) ∆WELM = 0.11 MJ (high ne) Type III
Nor
mal
ised
∆T e,
ped/T
e,pe
d
r/a
VELM from fast ECE
decrease of ∆TELM not of VELM " ∆WELM
similar results in DIII-D (Leonard) 0.0 0.5 1.00.0
0.1
0.2
0.3
0.4
0.5
∆Te,
ELM/T
e,pe
d
ν*(neo)
Type I ELMs Type III ELMs
∆WELM down by ~ 3 at VELM ~ constant !!∆WELM #"ELM affected Volume
JET-Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 21
Main plasma ELM energy/particle losses (IV)
Variation of ∆WELM #" ELM energy transport (DIII-D, JET)
∆WELM = ∆WELMcond (∆TELM) + ∆WELM
conv (∆nELM)
∆WELMcond decreases with ne,ped (or νe,ped(neo))
Smaller ∆WELM #" convective ELMs
DIII-D-Leonard PPCF�02
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 22
Main plasma ELM energy/particle losses (V)
0.0 0.2 0.4 0.6 0.80.00
0.25
0.50Inc
reasin
g q95
2MA q95 = 3.7 2MA q95 = 4.7 2.5MA q95 = 3.6 2.5MA q95 = 4.5
DOC-L δ = 0.27 HT3 δ = 0.45
∆Te,
ELM
/Te,
ped
ν*(neo)
∆WELM #" ∆TELM
MHD pedestal stability affects ∆WELM through ELM energy conduction
0.0 0.2 0.4 0.6 0.80.00
0.05
0.10
0.15
0.20
0.25 2MA q95 = 2.8 2MA q95 = 3.7 2MA q95 = 4.7 2.5MA q95 = 3.0 2.5MA q95 = 3.6 2.5MA q95 = 4.5
Increa
sing q
95
∆WE
LM/W
ped
ν*ped(neo)
DOC-L δ = 0.27 HT3 δ = 0.45
ITER
0.0 0.1 0.2 0.3 0.4 0.5 0.60.00
0.05
0.10
0.15
0.20
Increa
sing q
95
2MA q95
= 3.7 2MA q95 = 4.7 2.5MA q
95 = 3.6
2.5MA q95 = 4.5
DOC-L δ = 0.27 HT3 δ = 0.45
∆ne,
ELM/n
e,pe
d
ν*(neo)
high q95 + δ " small ∆WELM at low ν*ped - npedJET-Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 23
Main plasma ELM energy/particle losses (VI)
0.6 0.7 0.8 0.9
0.0
0.2
0.4
0.6
0.8
1.0
Nor
mal
ised
∆T e,
ped/T
e,pe
d
r/a
Pulse No. 59353 HT3 2.5MA/2.7T Pulse No. 58112 HT3 2.5MA/3.4T
0.0 0.2 0.4 0.6 0.80.00
0.25
0.50
Increa
sing q
95
2MA q95 = 3.7 2MA q95 = 4.7 2.5MA q95 = 3.6 2.5MA q95 = 4.5
DOC-L δ = 0.27 HT3 δ = 0.45
∆Te,
ELM
/Te,
ped
ν*(neo)VELM ~ constant with q95!!
effect of high q95 on P-B stability largest at high δ
ASDEX Upgrade-Saarelma NF�03
P-B stability effect on ELMs "non-linear evolution
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 24
Main plasma ELM energy/particle losses (VII)
0.6 0.7 0.8 0.9
0.0
0.2
0.4
0.6
0.8
1.0
Nor
mal
ised
∆T e,
ped/T
e,pe
d
r/a
Pulse 55935 DOC-L 2MA/2.4T Pulse 55955 DOC-U 2MA/2.4T Pulse 58409 DOC-U 2.5MA/2.7T Pulse 59353 HT3 2.5MA/2.7T
Plasma shape (δ, κ, �) changes VELM as expected from P-B analysis(JET & DIII-D (TTF�02-Córdoba) not ASDEX Upgrade (Urano PPCF�03))
0.0 0.2 0.4 0.6 0.80.00
0.05
0.10
0.15
0.20
0.25
∆WEL
M/W
ped
ν*(neo)
DOC-L 2MA/2.4T q95=3.7 δ=0.27DOC-U 2MA/2.4T q95=3.7 δ=0.32DOC-U 2.5MA/2.7T q95=3.1 δ=0.32HT3 2MA/2.2T q
95=3.6 δ=0.45
HT3 2.5MA/2.7T q95
=3.6 δ=0.45
lower ∆WELM/Wped for same ν*ped at high δbut
∆WELM is larger for higher δ (higher Wped) !!!
JET- Loarte PPCF�02JET- Loarte APS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 25
Main plasma ELM energy/particle losses (VIII)
Collapse of effect of pedestal plasma at ELM is not Θ symmetricASDEX Upgrade-Nunes EPS�03 subm. NF�04
√ψ
0.8
α↑↑↑↑ jedge↑↑↑↑
1.0.9
ballooning structure is maintained to the end of the ELM collapseSimilar results in JT-60U (Oyama NF�03 & NF�04) & MAST (Kirk PPCF�04)
flux mapped profiles
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 26
Main plasma ELM energy/particle losses (IX)
Delay scales with LFS-HFS ion transit time!
Collapse of pedestal plasma during ELMs is not simultaneous at all Θ
ASDEX Upgrade-Nunes EPS�03 subm. NF�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 27
Main plasma ELM energy/particle losses (X)ELMs are triggered at precise values of ne,ped and Te,ped
ELM crash has a much wider scatter for same ne,ped and Te,ped
0.0 0.5 1.0 1.5 2.00
10
20
30
40
Freq
uenc
y
∆WELM/<∆WELM>0.0 0.5 1.0 1.5 2.00
10
20
Freq
uenc
y
∆Tped,ELM/<∆Tped,ELM>0.0 0.5 1.0 1.5 2.00
10
20
30
Freq
uenc
y∆nped,ELM/<∆nped,ELM>
0.0 0.5 1.0 1.5 2.00
10
20
30
40
Freq
uenc
y
nped,ELM/<nped,ELM>
0.0 0.5 1.0 1.5 2.00
10
20
30
Freq
uenc
y
Tped,ELM/<Tped,ELM>
JET-Loarte APS�03ne,ELM
Te,ELM
∆Te,ELM ∆ne,ELM∆WELM
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 28
ELM energy/particle fluxes to PFCs (I)
Eich submitted NF 2003
∆WELM " divertor and main chamberParameters to be determined & understood :! timescales and areas! transport mechanisms (extrapolation)
Outerdivertor
Innerdivertor
ELMs lead to fluxes both at the divertor and main chamber PFCsASDEX Upgrade-Eich PRL�04 ASDEX Upgrade-Herrmann EPS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 29
ELM energy/particle fluxes to PFCs (II)
divertor ELM fluxes are toroidally symmetric near separatrix (long Lc/high S)ASDEX Upgrade-Eich PRL�04DIII-D Leonard JNM�97 (Loarte PPCF�03)
but ELM currents in DIII-D?
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 30
ELM energy/particle fluxes to PFCs (III)
Outerdivertor
Innerdivertor
divertor ELM energy wetted area ≈ divertor wetted area between ELMs
ASDEX Upgrade-Herrmann PPCF�02 (Loarte PPCF�03)
┴ B & II B are enhanced in a similar way during ELMsSimilar results in MAST (Kirk PPCF�04) and DIII-D (Fenstermacher PPCF�03)
JET-Eich PSI�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 31
ELM energy/particle fluxes to PFCs (IV)
Significant fraction of ∆WELMdiv arrives after Tmax
surf !!!!ELM erosion in ITER determined by Tmax
surf > TevapC
Tmaxsurf
Time history of divertor ELM energy is complexJET-Eich PSI�02, Matthews NF�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 32
ELM energy/particle fluxes to PFCs (V)
0.1 10.0
0.1
0.2
0.3
0.4
0.5DOC-L δ = 0.27
1.2MA q95 = 3.12MA q95 = 3.72MA q95 = 4.63MA q95 = 3.1
∆WE
LMou
t(0<
t <τ IR
)/∆W
ELM
out t
ot
ν*(neo)
nped or ν*(neo) " ELMs more convective " more of ∆WELMdiv after Tmax
surf
0.40 > ∆WELMdiv (0<t<τIR)/ ∆WELM
divtot > 0.15
conductive ELM convective ELM
ratio
JET-Loarte APS�03, Eich PSI�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 33
ELM energy/particle fluxes to PFCs (VI)
Timescale of ELM heat flux on divertor correlated with τII ~ L/cs,ped
PIC-Bergmann NF�02τELMMHD
JET- Eich, ASDEX Upgrade-Herrmann,JT-60U Asakura, MAST-Kirk
Experiment " high Γx-ray (electrons ~ keV) during τELMMHD
! Γdiv = Γe,div(τELMMHD) + Γi,div(τII)
! Formation of high energy sheath
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 34
ELM energy/particle fluxes to PFCs (VII)
� ∆WELM/Wped decreases with τII
cRq
pedsFront
,952ππππττττ ====||
Physics Model :
1) Pedestal connects to divertor for τELMMHD
2) Energy flow restricted by sheath (τII) " ∆WELM/Wped ~ (1-exp(-τELMMHD/τII))
ITPA-Loarte PPCF�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 35
ELM energy/particle fluxes to PFCs (VIII)separation of e- flux (τELM
MHD) & ion flux inner divertor
Similar results from DIII-D (Fenstermacher PPCF�03, Boedo APS�03)
150 200 250 300 350 4000
200
400
600
800Empty symbols Type IIIDOC-L δ=0.27
~ 2.2 x (ττττII-175)
∆tD
α (µs)
τII (µs) = L/csped
1.2MA q95 = 3.11.2MA q95 = 3.12.0MA q
95 = 2.8
2.0MA q95 = 3.72.0MA q95 = 3.72.0MA q95 = 4.63.0MA q95 = 3.1
JET-Loarte, PPCF�02, PPCF�03, APS�03
∆tDα ~ 0 for finite τII
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 36
ELM energy/particle fluxes to PFCs (IX)
∆tDα ~ 0 for finite τII : a) main plasma collapse (τELMMHD ≠ 0) ?
b) change of ELM start X-point " midplane ?DIII-D-Fenstermacher PPCF�03 ASDEX Upgrade-Nunes EPS�03 subm. NF�04
In-out divertor
HFS-LFS main plasma
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 37
ELM energy/particle fluxes to PFCs (X)
0.05 0.10 0.15 0.200.0
0.2
0.4
0.6
0.8
1.0
1.2DOC-L δ = 0.27 1.2MA q95 = 3.1
2MA q95 = 3.72MA q95 = 4.63MA q95 = 3.1
∆WEL
MIR
/∆W
ELM
∆WELM/Wped
larger ∆WELM/Wped " smaller ∆WELMdiv /∆WELM
Transient radiation #" ∆WELMdiv < ∆WELM
∆WELMdiv < ∆WELM but λELM
div ~ λinter-ELMdiv
JET-Loarte APS�03, Eich PSI�04ASDEX Upgrade Herrmann EPS�97 (Loarte PPCF�03)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 38
ELM energy/particle fluxes to PFCs (XI)
vr (km/s): JET (0.5-1.2, Gonçalves PPCF�03, Fundamenski�04), MAST (0.2-1.7, Counsell PPCF�02, Kirk PPCF�04), DIII-D (0.2-0.6, Zeng PPCF�03, Boedo APS�3)
large particle fluxes measured far from separatrix at ELMsDIII-D-Boedo+Zeng APS�03/PPCF�04 MAST-Counsell PPCF�02
τperp,ELM~100 µs~τII " large Γmain chamber
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 39
ELM energy/particle fluxes to PFCs (XII)
significant energy fluxes measured on main chamber PFCs
Energy on PFCs on large area of limiter (most ELMs)∆WELM
wall ~ 25 % of ∆WELM
Te,ELMPFC << Te,ped " Ti,ELM
SOL
ASDEX UpgradeHerrmann EPS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 40
ELM energy/particle fluxes to PFCs (XIII)What do we know about radial ELM fluxes ?
complex filamentary
rotating structure
DIII-D-Boedo-Fenstermacher APS�03 /PPCF�03 DIII-D-Boedo APS�03
Te,ELM decays radially faster than
ne,ELM
τE-e,SOL < τII
vr,ELM decreases with ne (and r ?)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 41
ELM energy/particle fluxes to PFCs (XIV)
decrease of vr with ne (and ∆WELM?) compatible with ∆WELM
div/∆WELM
0.05 0.10 0.15 0.200.0
0.2
0.4
0.6
0.8
1.0
1.2DOC-L δ = 0.27 1.2MA q95 = 3.1
2MA q95 = 3.72MA q95 = 4.63MA q95 = 3.1
∆WEL
MIR
/∆W
ELM
∆WELM/Wped
JET-Loarte APS�03, Eich PSI�04
DIII-D-Zeng PPCF�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 42
δδ
δ
ELM energy/particle fluxes to PFCs (XV)What determines vr?
1.Non-linear ballooning explosive mode dependence on (ne, Te, ν*ped)
S.Cowley-PPCF�03
JET-Becoulet-H-mode WS�01
ELM Bθ �amplitude� decreases with nped~
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 43
ELM energy/particle fluxes to PFCs (XVI)
vr = cs 2ρ2L/Rrb2
! JET : Tped ~ 1.5 keV, if rb ~ 20 cm " vr ~ 1 km/s! DIII-D : Tped ~ 0.5 keV, if rb ~ 13 cm " vr ~ 1 km/s
Scaling of vr ~ Tped3/2 rb
-2 ~ nped-3/2 rb
-2
2. Dynamics of ELM pressure blob radial transport (Krasheninnikov, D�Ippolito,�.)
dependence of rb on nped, Tped , 2 hypothesis :
! Empirical ∆NELM ~ nped (DIII-D, JET, ASDEX Upgrade)
rb ~ constant
! rb ~ P-B mode width " rb ~ nped−α
ASDEX Upgrade-Nunes EPS�03 subm. NF�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 44
Extrapolation of Type I ELMs to ITER
WdiaITER = 350 MJ " Wped < 0.4 Wdia
ITER =140 MJ (nped~8 1019 m-3 Tped~4.3 keV)
τIRELM ~ 300 µs
AELMITER = A S.S
ITER = 3 m2 (λpowermidplane = 5 mm)
Convective ELMs Conductive ELMs
∆WELMITER (MJ) 10 28
∆WELMITER, div(MJ) 80% 50%
∆WELMITER,div (0 < t < τIR) (MJ) 20% 40%
ΦELMITER (MJm-2s-1/2 ) 20 72
C-ablation in ITER ~ 50 MJm-2s-1/2
∆WELMITER,wall (MJ) 20% 50%
ELM erosion less critical than previously believed even for conservative assumptions
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 45
Conclusions (I)
$ Peeling-Ballooning model provides a reasonable description ofpedestal pressure limitation by Type I ELMs
! Detailed multi-machine comparison (& pedestal width scaling) in progress
! Which is the ELM triggering mechanism ?
! Non-linear evolution of ELM and timescales
$ Type I ELM energy losses determined by ne,ped & Te,ped, q95, δSmall ELMs #" Convective ELMs
! What determines VELM ? ! Physical process that produce convective ELMs (ν*ped and high δ/q95) ?
(link between MHD stability #" ELM energy transport ?)! What determines the ELM variability ?
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 46
Conclusions (II)
$ ELM energy fluxes determined by determined by ne,ped & Te,ped
! timescale of ELM energy flux on divertor by τII and not τELMMHD
(role of sheath/IIB transport on divertor ELM energy Flux ?)
! ∆WELMdiv < ∆WELM and fluxes to main chamber PFCs
(convective radial ion transport versus IIB losses ?)
! spatial distribution of ELM heat loads
(toroidal symmetry ?, main chamber fluxes ?, in/out divertor balance ?)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 47
Conclusions (II)
$ ELM energy fluxes determined by determined by ne,ped & Te,ped
! timescale of ELM energy flux on divertor by τII and not τELMMHD
(role of sheath/IIB transport on divertor ELM energy Flux ?)
! ∆WELMdiv < ∆WELM and fluxes to main chamber PFCs
(convective radial ion transport versus IIB losses ?)
! spatial distribution of ELM heat loads
(toroidal symmetry ?, main chamber fluxes ?, in/out divertor balance ? )
$ Regimes with small/no Type II ELMs/good confinement exist but:! operational space is narrow and not well characterised
(reproducibility in various experiments ?) ! extrapolability to next step devices/compatibilty with other requirements ?
(low ν*ped, low q95, high Praddivertor, pellet fuelling, He pumping, �.)
! operation close to double null required ?
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 48
Regimes with high Pped + small/no ELMs (I)
Regimes with small or no ELMs and high Pped
a) Regimes with high Pped and small ELMs (Type II ELMs : JT-60U, AUG)
modification of edge MHD plasma stability
b) Regimes with no (or infrequent) ELMs and quasi-continuous losses (EDA, QH-mode, �mixed Type I-II ELMs� in JET)
triggering of transport losses �between ELMs� Pped ≤ Ppedlimit
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 49
Regimes with high Pped + small/no ELMs (II)
Mixed Type I-II in JET #" increased broadband MHD fluctuation at low f Tped reaches steady state between type I ELMs with increased fluctuations but
nped does NOT saturate in the Type II phases (" end in Type I)
Increased Inter-ELM transport (+ washboard modes)
JET-SaibeneEPS�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 50
Regimes with high Pped + small/no ELMs (III)
QH (and EDA) no-ELM regimes are associated with coherent MHD modes at the edge which lead to enhanced transport
DIII-D Doyle PPCF�02, Burrell
PPCF�03
potentially interesting for next step devices but triggering of mode?
reproduced in ASDEX Upgrade
Suttrop PPCF�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 51
Regimes with high Pped + small/no ELMs (IV)
JT-60 Type II ELM (= Grassy ELM) discharges are obtained at high δ, high βp and high q95 (low ν*ped)
JT-60U � Kamada PPCF�02
0.01
0.1
1
10
0.5 1.0 1.5 2.0 2.5
JT60-U
, Type I (high βp and H-mode)
, Type II and mix (high βp)
Type III (H-mode)
βp
ν *
change of ELM Type because of edge stability change due to Shafranov-shift
reproduced at JET Saibene EPS�04
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 52
Regimes with high Pped + small/no ELMs (V)
! PpedType I ~ Pped
Type II transition! Regime is robust to Pin ↑ (if fuelling adjusted)! attributed to change in edge P-B stability! compatible with high β (βN , ν*ped interplay?)
Type II (0.35<δ<0.42, 0.8<Ip(MA)<1)Type III
ASDEX-Upgrade-Stober NF�02ASDEX-Upgrade-Sips NF�02
Type II ELMs in ASDEX Upgrade occur at high nped (ν*ped)
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 53
Regimes with high Pped + small/no ELMs (VI)
! Type II require medium/high δ and ne
! Proximity to DN configuration is essential (no type II for ∆Xmp>2cm) + Trade-off δ/q95 ? ! High β not required, but compatible with the regime! (βN~3 obtained)
not reproduced at JET Saibene EPS�03
3.0 3.5 4.0 4.5 5.00.25
0.30
0.35
0.40
0.45
0.50
ASDEX-U
q95
vs average δ
<δ >
q95
Type I Type III Type I+II Type II
-3.5 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.00.25
0.30
0.35
0.40
0.45
0.50
ASDEX-U
Type I Type III Type I+II Type II
<δ>
∆X separatrices midplane (cm)
Type II in ASDEX-U : Quasi DN configuration
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 54
Regimes with high Pped + small/no ELMs (VII)
ASDEX Upgrade-Saarelma NF�03
proximity to DN (#15863) leads to a sharp decrease of eigenmode width
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 55
Physics of ELM instability (V)Growth of linear mode coincident con ELM crash (low ne)
DIII-D-Snyder APS�01
Similar results for giant ELMs in JET - Huysmans
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 56
Physics of ELM instability (IX)
JET-Ghendrih JNM�03Between ELMs
Analyses of particle impact patterns on JET main wall are consistent with ballooning mode n = 12, m = 50
At ELMs
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 57
Physics of ELM instability (XIII)JT60U-Oyama PPCF�01
τELM ~ 200 µs
DIII-D-Fenstermacher PPCF�03
τELM ~ 200 µs
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 58
Main plasma ELM energy/particle losses (XI)
ELM perturbation into edge plasma much broader than P-B modesDIII-D-Leonard APS�02
Relation between ∆WELM
and P-B modes ?
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 59
ELM energy/particle fluxes to PFCs (XVII)
� ∆WELM/Wped decreases with τII
cRq
pedsFront
,952ππππττττ ====||
Physics Model :
1) Pedestal connects to divertor for τELMMHD
2) Energy flow restricted by sheath (τII) " ∆WELM/Wped ~ (1-exp(-τELMMHD/τII))
ITPA-Loarte PPCF�03
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 60
ELM energy/particle fluxes to PFCs (XVII)
In/Out ELM energy balance changes at ELM and with divertor/main plasma conditions
DIII-D-Leonard PSI�02, Fenstermacher PPCF�03
consistent with Ndivin > Ndiv
out + sheath or changes in with energy flow with ne
Energy fluxes at ELMs
Inter-ELMndiv
in > ndivout
Tdivin < Tdiv
out
qdivin < qdiv
out
Γdivin > Γdiv
out
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 61
Out
In
ELM energy/particle fluxes to PFCs(XVIII)
0.0 0.5 1.0 1.5 2.00
10
20
30
100 µsτELM 500 µs 1 ms
Carbon Atom
/ELM
µm/E
LM
EnergyELM (MJ/m2)
0.0
5.0x1022
1.0x1023
1.5x1023
2.0x1023
2.5x1023
3.0x1023
3.5x1023
4.0x1023
EELM > 1MJ/m2 can lead to ΓC > 1023 C-atom/ELM
ND-TITER ~ 1023 particles
Poor C Retention in Divertor @ ELM(Plasma flows out of the Divertor)
Large Proportion of ΓC may get into Core Plasma " increase of Zeff at edge
A. Loarte 2004 International Sherwood Theory Conference � Missoula � Montana 28 � 4 � 2004 62
ELM energy/particle fluxes to PFCs (XIX)
JET MkII: 1 MJ ELMs
time (s)
Wdi
a (M
J)Z
eff
11
12
10
1 MJ
10
20
Pin
, Pra
d (M
W)
2.0
3.0
Ha
! EtransientC-radiation (3 keV, 8 1019 m-3) ~ 1 keV/atom
EELMRAD ~ 16 MJ << Wplasma (~ 350 MJ)
! JET Results agree qualitatively : Modelling/Extrapolation to ITER necessary
EELMRAD ~ 0.5 MJ(C. Ingesson)
Wp~ 11 MJ∆WELM ~ 1 MJ
Energy loss by Carbon Transient Radiation " Probably smallADAS � M. O�Mullane
nped ~ 8 1019 m-3
Tped ~ 3 � 5 keV
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