30 th EPS, St. Petersburg, 7-11 July, M. Bécoulet 1/32 30 th EPS, St. Petersburg, July 2003 M. Bécoulet Edge Localised Modes Physics and Edge Issues in Tokamaks. presented by Becoulet M. G. Huysmans (1) , Y. Sarazin (1) , X.Garbet (1) , Ph. Ghendrih (1) , F. Rimini (1) , E. Joffrin (1) , Litaudon X. (1) , P. Monier-Garbet (1) , J.-M. Ané (1) , P. Thomas (1) , A. Grosman (1) , (1) Association Euratom-CEA, CE Cadarache, F-13108 St. Paul-lez-Durance, France. V.Parail (2) , H. Wilson (2) , P. Lomas (2) , P. deVries (2) , K.-D. Zastrow (2) , G.F. Matthews (2) , J. Lonnroth (2) , S. Gerasimov (2) , S. Sharapov (2) , M. Gryaznevich (2) , G. Counsell (2) , S.Fielding (2) , A. Kirk (2) , M. Valovic (2) , R. Buttery (2) , (2) Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA, UK. G. Saibene (3), R. Sartori (3) , A. Loarte (3) ; (3) EFDA Close Support Unit (Garching), 2 Boltzmannstrasse, Garching, DE. A.Leonard (4) , P. Snyder (4) , L.L. Lao (4) , P. Gohil (4) , T.E.Evans (4) , (4) General Atomics, 3550 General Atomics Court,P.O.Box 85608 San Diego,CA,U.S.A. Y Kamada (5) , A Chankin (5) , N. Oyama (5) , T.Hatae (5) ,N. Asakura (5) , (5) Japan Atomic Energy Research Institute (JAERI), Japan O. Tudisco (6) , E. Giovannozzi (6) , F. Crisanti (6) , (6) Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati , Italy C. P.Perez (7) , H. R. Koslowski (7) , (7) Institut für Plasmaphysik, Forschungszentrum Julich, Germany T.Eich (8) , A. Sips (8) , L. Horton (8) , P. Lang (8) , A. Hermann (8) , J. Stober (8) , W. Suttrop (8) , (8) Association Euratom-IPP, MPI fur Plasmaphysik, 2 Boltzmannstrasse, Garching, D-85748, Germany P. Beyer (9) , (9) UMR 6633PIIM CNRS-Université de Provence,F-13397 Marseille Cedex 20, France. S. Saarelma (10) , (10) Helsinki University of Technology, Euratom-TEKES Association, FIN-02015 HUT, Association Euratom-Cea
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30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 1/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Edge Localised Modes Physics and Edge Issues in Tokamaks.presented by Becoulet M.
G. Huysmans (1), Y. Sarazin (1), X.Garbet(1), Ph. Ghendrih (1), F. Rimini (1), E. Joffrin (1), Litaudon X. (1), P. Monier-Garbet (1) , J.-M. Ané (1), P. Thomas (1), A. Grosman (1),
(1) Association Euratom-CEA, CE Cadarache, F-13108 St. Paul-lez-Durance, France.V.Parail (2), H. Wilson (2), P. Lomas (2), P. deVries(2) , K.-D. Zastrow(2), G.F. Matthews (2), J. Lonnroth (2), S.
Gerasimov(2), S. Sharapov(2), M. Gryaznevich(2), G. Counsell(2), S.Fielding(2), A. Kirk(2), M. Valovic(2), R. Buttery(2) ,(2) Euratom/UKAEA Association, Fusion Culham Science Centre, Abingdon, OX14 3EA, UK.
G. Saibene (3), R. Sartori (3), A. Loarte (3) ;(3) EFDA Close Support Unit (Garching), 2 Boltzmannstrasse, Garching, DE.
A.Leonard (4), P. Snyder (4), L.L. Lao(4), P. Gohil(4), T.E.Evans(4), (4) General Atomics, 3550 General Atomics Court,P.O.Box 85608 San Diego,CA,U.S.A.
Y Kamada (5), A Chankin (5), N. Oyama(5), T.Hatae(5) ,N. Asakura(5),(5) Japan Atomic Energy Research Institute (JAERI), Japan
O. Tudisco (6), E. Giovannozzi(6) , F. Crisanti(6),(6) Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Frascati , Italy
C. P.Perez (7), H. R. Koslowski(7) ,(7) Institut für Plasmaphysik, Forschungszentrum Julich, Germany
T.Eich(8), A. Sips(8), L. Horton(8) , P. Lang (8), A. Hermann (8), J. Stober(8), W. Suttrop(8), (8) Association Euratom-IPP, MPI fur Plasmaphysik, 2 Boltzmannstrasse, Garching, D-85748, Germany
P. Beyer(9),(9) UMR 6633PIIM CNRS-Université de Provence,F-13397 Marseille Cedex 20, France.
S. Saarelma(10),(10) Helsinki University of Technology, Euratom-TEKES Association, FIN-02015 HUT, Finland
R.A. Moyer (11)
(11) University of California, San Diego, La Jolla CA 92093,U.S.A. and contributors to JET-EFDA Workprogramme.
AssociationEuratom-Cea
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 2/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
1. Introduction. -High confinement scenarios for ITER and ELMs.
2. H-mode scenarios and ELMs (theory + experiment).-Ballooning-peeling linear MHD model.- Pedestal and SOL transport, non-linear models.-ELM size: role of density, triangularity, high q95, high p. -High confinement regimes with Type II ELMs for ITER?
3. Internal Transport Barrier (ITB) scenario and ELMs.
- Combined ITB+ ETB scenarios.
4. Active control of ELMs.-Edge ergodisation, edge current, pellets.
Outline.
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 3/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
ELM = plasma edge MHD instabilities typical for H-modes in tokamaks => periodic fast (200s) relaxations of edge pressure => energy to SOL =>divertor+wall.
D
Wdia
Te ped
ne ped
JET: Ph.Ghendrih JNM (2003)
divertor
JET: G. Saibene PPCF2002
ELM cycle: periodic loss of confinement
time(s)
after
after
before
before
DIII-D:- A. Leonard PPCF2002
ne=> convective
Te=> conductive
radius(m)
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Type I : low fELM, high Pped=> high confinement,but large energy losses per ELM.
Type II : regimes in highly shaped plasmas, high Pped, (confinement ~like Type I ELMs), small edge MHD activity, but for narrow operational window.
Type III: (at low power or at high density): higher fELM, small energy losses per ELM, but lower Pped=> low confinement.
Experimental scaling for ELMs types
L-modeH-m
ode:Type I
IIType I
I
JET: Sartori R. PPCF2003 submitted
H-mod
e:Typ
e I
L-mode
L/H threshold ~0.45ne 0.75 BTR2 (MW)
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 5/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
ITER reference scenarios Q=Pfusion/Padd.~10(Aymar et al 2001) :
high confinement (H98y>1); high density (>0.8nGR), high
and
acceptable (material limits=melting, erosion,evaporation…=>reasonable divertor life-time) heat loads on the divertor target plates: WELM
ped<5-10MJ (if 60% goes to the divertor S~3m2 )(Federici PSI 2002).
ELMs are problematic for ITER.pr
essu
re
radius
ET
B
core
pedestal pressure(=confinement)is limited by MHD
H-mode scenario(or advanced regimesw/o ITB?)
heat
flu
x to
SO
L
radius
ITB
ITB scenario
ITB erosion by large ELMs
pres
sure
heat
flu
x to
SO
L
ET
B
ITB
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 6/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
plasma
Experiment evidence from many tokamaks: ballooning structure
MAST: G.Counsell 2002
Te, ne collapse on LFS
-Ballooning structure of ELMs=> collapse of Te, ne on the LFS.-Parallel SOL transport => divertor (~50% : T.Eich EPS2001 ); -SOL perpendicular turbulent transport (“tails”, “blobs”) => wall
Outboard D
MAST: A. Kirk 2003
wall
plasma edge
inboard outboard
beforeduringafter
SOL
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 7/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Linear ideal MHD theory: ELMs=ballooning-peeling modes.
Linear MHD stability analysis (codes MISHKA, GATO, ELITE).
-Ballooning modes driven by pressure gradient => pedestal, outboard (=LFS), high n.-Peeling (kink) driven by edge current (+bootstrap) =>X-point, low n=1-4
-Coupled peeling-ballooning => LFS, pedestal, n~10-20 (JET).JET: M. Becoulet et al PPCF2002
jedge
ballooning-peeling: n=12
JET(MISHKA): G.Huysmans 9thEFPW 2001
0.8 1
Ped
esta
l sho
ulde
r
20
B
P2q0
Pee
ling
com
pone
nt
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30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 9/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Resistive ballooning turbulence (B=0, =0 ) modelling : periodic energy bursts through ETB. Estimations for “ELM” time ~250s! More development needed both with MHD + turbulence (DIII-D, BOUT-X.Xu et al
New J. of Phys. 2002)
(P.Beyer ,to be submitted PoP2003)
Turbulence modelling: ELMs?
SOLcore
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ELM collapse on the LFS => inner/outer delay in D t delay~ // (ions) =2Rq95/Cs, ped . Increases with the density.
JET : A. Loarte et al PPCF2002
Particle transport in SOL to the inner and outer divertor.
OuterLFS
InnerHFS
ELM collapse
innerouter
LFS
HFS
JT-60U: A.Chankin, N. Oyama et alNF2002, PPCF 2001
dB/dt
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Type I ELM time: divELM > ~ MHD
ELM
MHDELM ~ 150-300 s (JET),
similar in JT-60U, DIII-D, AUG~1ms. Not identified parametric dependence. Weak?
IR data
Energy into divertor is deposited with ion flux time //
ion => divELM
increases with the density.
JET: A.Loarte PPCF2002
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 12/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Toroidal asymmetry of Type I ELM in JET (similar TCV: H. Reimerdes
NF1998). Propagation in electron diamagnetic direction: ~SOL// . Not
explained by linear MHD.
toroidal Mirnov coils
Toroidal “rotation” of ELM
JET(M.Becoulet, G. Saibene 2003)
Broken coils
Low nped High nped
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What physics? ne => Te
ELM “size” decreases with the density.
What are the key factors to decrease ELM size keeping high confinement? Multi-machine experimental scaling: WELM/Wped decreases with with ne, ped (*ped,, Front
// … ).
ineoen~ETB
2/5eT~
//
-SOL transport?
-Pedestal transport?
A. Loarte PPCF 2002-MHD=>bootstrap current
2/3eT/
effZ~
// =2Rq95/Cs, ped
Not identified yet;
ee95
Rq
Log scale
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 14/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
MISHKA modelling for JET: diffusion of edge bootstrap current improves stability for low n peeling modes. Main difficulty: sensitivity of stability diagram to small changes in Te, ne, Jz profiles, no direct measurements of edge current.
JET(MISHKA): G.Huysmans 9thEFPW 2001
Edge bootstrap current decreases with density.
unsta
ble
stabl
e
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 15/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
As density increases pedestal width (less obvious on JET!), bootstrap current , mainly conductive losses T/T with densityModelling => Radial width of mode decreases =>Smaller ELMs?
DIII-D (ELITE: P.Snyder et al IAEA 2002)
ELM size =ELM affected area? Open question.
DIII-D (A. Leonard et al, PPCF-2002)
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Transport modelling(TELM): smaller affected area = smaller ELMs?
TELM ( M. Becoulet et al 2003)
Large ELM area : WELM/Wped~3% Narrow ELM area: WELM/Wped~1.2%
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 17/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
JET(MISHKA): G.Huysmans 9th EFPW 2001JET: G. Saibene et al PPCF2002
Edge current
Pre
ssur
e gr
adie
nt
Low High
ELM size: role of plasma shaping=> improved MHD stability
ITER
stablestable
Similar results for AUG,JT-60U, DIII-D…
kink unstable
Ballooning unstable
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 18/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
High confinement regimes with small “grassy” ELMs recipe =>high magnetic shear: , high q95=3.5- 6, high p~2.
high p(~2 ) helps =>grassy” at q95=3.6 (in ITER~3)
JT-60U Y. Kamada et al PPCF2002
High triangularity (edge magnetic shear)=>“Grassy” ELMs in JT-60U
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 19/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Type II ELMs in ASDEX-Upgrade.
Type II ELMs : =0.4 (Double Null is important!), q95>4.2, n/nGR~0.85-0.95(high density) , H98~1. Broadband MHD: n=3,<30kHz. Low heat load into divertor.Advanced scenario with Type II at high p.(0.8MA/1.7T, 10MW NBI)=0.4 (Double Null configuration)q95=3 (q0~1 to avoid saw-teeth)n/nGR~0.88, H 98-P~1.2-1.3, p=1.8, N=3.5Effect of high p?-Core confinement is improved (turbulence; bootstrap =>flat shear…) -ELMs Type II at lower q95 ~3.
AUG: A. Sips 9thEFPW 2001
To Double Null
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 20/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
ELM affected area decreases at high q95 +high for the same pressure profile. Double Null configuration increases edge shear even more.
GATO (for AUG) S. Saarelma et al, NF(2003)
Linear ideal MHD (GATO): ELM area is small for Type II ELMs
n=3
n=3
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 21/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
; q95=3.4, n/nGR~0.9-1.1, H97~1. High density (*~0.6-0.8!) => smaller Type I + Type II = broad band MHD <30kHz, n=8 (Washbroad resistive modes? Ch.Perez NF2003). SN and DN configurations were tried. Not enough factors JET to suppress Type I ELMs on JET? And for ITER? Other regimes w/o ELMs QH (DIII-D), EDA(C-mod)…
JET: G. Saibene et al PPCF(2002), see EPS 2003
ne=0.8nGR
ne=1.1nGR
JET: mixed Type I+Type II
D
D
Wdia
nene
Wdia
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 22/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
-Ideal MHD + transport models describe many experimental observations: ballooning structure, fast relaxation of Pped, MHD ELM time:ELM, frequency: fELM.
- Type I ELM MHD time (= typical pedestal crash time) is found ~150-300s for many machines. Parametric dependence is not identified yet.-ELM rise time on divertor target is correlated with ion // SOL transport. - Key factors to decrease ELM size?
-high pedestal density(collisionalty?); -high , high q95, high p;
-Regimes with benign Type II ELMs at high demonstrated ITER–like H97~1, n/nGR~0.8-0.9, but not for ITER-like parameters (*~0.05, p~1, q95~3)=> Low *, high power, high current…
Conclusions (I): ELMs in H-modes
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 23/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Double barriers: ETB+ITB: high p with “grassy” ELMs.
High p~2, high q95~6.9, high => ITB+ETB with grassy ELMs => high performance (HHy2~1.2, n/nGR~0.6) + divertor heat load is reduced by factor 4-5 as compared to Type I ELMs.
JT-60U: Y. Kamada PPCF(2002)
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 24/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
D-III-D: P. Gohil 8th IAEA TCM2001
Quiescent Double Barrier =ITB+QH-mode without Type I ELMs on DIII-D (bN=3.5, wide range of q95, ). But : counter NBI injection, nped~0.1nGR. Interesting from the point of view: low * pedestal.
QDB
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 25/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Usually Type I ELMs are not compatible with large ( ITB> 0.5) ITBs in JET, DIII-D: ITB erosion by Type I ELMs. If no pure Type II regimes => small Type III ELMs +ITB (=improved core confinement to compensate poor edge confinement). But how to keep Type III edge?
JET: M. Becoulet PPCF(2002)
Type IIIType I
ITB+Type I ELMs ? Type III ELMs?
Te (ECE)wall
plasma centre
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 26/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Suggestion from theory: perturbation from ELM propagates inside => fast avalanche-like transport after an ELM: inward –outward turbulent fluxes. Why ITB is affected? Slow ( confinement) erosion of ITB, not MHD collapse! Rotation shear is affected ? Mechanism is unknown.
JET: Y. Sarazin PPCF(2002)
before 1st ELM
before 2nd ELMsteep gradients
Avalanche
Average profile
Steeper gradient=> unstable
Perturbation from Type I ELM propagates to ITB region?
SOLcentre
pres
sureITB
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 27/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Main difficulty for ITB scenario at high ~0.5 is Type I ELMs avoidance. JET 2003: ITBs (3.4T/1.5MA) with Type III edge with D2: n/nGR~0.7, H98y~1.3, bN~1.8, p~1.5 , q95~7, lasts~ 6s.
JET: M. Becoulet , P. Lomas, O. Tudisco, F. Rimini, K.-D. Zastrow et al
High triangularity ITB on JET.
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 28/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 29/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
-Combined regimes with ITB and ETB: ITB with “grassy” ELMs at high triangularity, high q95,
high p were demonstrated in JT-60U. ITB+ETB w/o ELMs : QDB in DIII-D (but counter NBI,
low n/nGR~0.1)
-High triangularity ITBs (~0.5, n/nGR~0.7, H98y~1.3, bN~1.8, bp~1.5, q95~7 ) with Type III ELMs were demonstrated on JET.
Conclusions(II): ELMs in ITBs
Active control of ELMs: -gas puffing;-impurity (increased Prad=> control Te,ped, but impurity accumulation?)
-edge current (Ip ramp-up, -down experiments => support peeling-ballooning
picture of ELMs, but very Pped, dIp/dt dependent, large res ITER)-edge ergodisation,-pellets…
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 30/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
External control coils Br(t) => edge ergodisation: <crit, or artificial ELMs. Compatibility with high confinement regimes?
COMPASS-D: S. Fielding et al EPS2001TCV: A. Degeling et al 2003
R. Moyer,T. Evans : DIII-D (C-coils) EPS2002
Br
Br
MaxBr
MaxBr
ELMs control by Brexternal?
More planned in 2003
See G. Jackson , EPS 2003 Friday -P-4.47
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 31/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Pellets => increase of *, artificial ELMs are similar to natural.
Pellets.
ASDEX-Upgrade: P. Lang (EPS2002)see also this conference
W/o pellets: ~ 3Hz large compound ELMs
With pellets: 20 Hz smaller Type I ELMs
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 32/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
(towards ITER integrated scenario) 1. Key factors to decrease Type I ELM size:
-high , high q95, high p=> Type II ELMs for ITER?-increase pedestal density (*, //
ion,..?) => understanding of SOL energy and particles transport during an ELM is missing for the
definitive predictions for ITER.2. H-modes and combined advanced scenarios (with and w/o ITBs) at high triangularity high density with small ELMs demonstrated ITER –like performance (H97y>1, n/nGR~0.7-0.9) , but for the moment not for ITER-like parameters : *~0.05, p~1, q95~3 (H-mode); q95~4-5(ITB-scenario). Aim: high current, high power, low pedestal collisionality regimes!
3. Active control of ELMs is progressing => should demonstrate the compatibility with high confinement regimes for ITER.
Conclusions
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 33/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
increases with density => if < crit., no ELMs! , (first
demonstrated with JETTO: V. Parail EPS2001). But in experiment Type I=> Type III transition with ne increase, low confinement.TELM: M. Becoulet et al 2003
before
after
ETB
Transport through ETB increases with density=>smaller ELMs
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 34/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
Usually Type I ELMs are not compatible with large ( ITB> 0.5) ITBs in JET, DIII-D: ITB erosion by Type I ELMs. If no pure Type II regimes => small Type III+ITB(improved core confinement) ?
JET: M. Becoulet PPCF(2002)
Type IIIType I
ITB+Type I ELMs ? Type III ELMs?
Te (ECE)wall
plasma centre
JET: R.Sartori +M. Becoulet PPCF 2002
ITBs
Type IIIStandard H-
modes
Type I
L-mode
30thEPS, St. Petersburg, 7-11 July, 2003 M. Bécoulet 35/3230thEPS, St. Petersburg, July 2003 M. Bécoulet
55599
55601
Tped
nped(55601,55599)
JET: Becoulet M. et al 2003
dithering
larger Type I ELMs!Type I
Edge current (Ip ramp-up):1)first improve stability; 2)then destabilise peeling modes: (when kink unstable): Type III or dithering L-mode. The result is very sensitive to edge Te, ne, dIp/dt…res for ITER?
Ip ramp-up
Ip ramp-down
current
Balloonin
g
unstable
Pre
ssur
e gr
adie
nt
Ip ramp-upIp ramp-down
Low n kink
unstable
n=14-22
(similar results MAST : Gryasnevich M. et al 2002; COMPASS-D, S. Fielding EPS2001 )