Radial propagation of Type-I ELMs on JET W.Fundamenski, W.Sailer 15.7.2003 ITPA, St.Petersburg 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial propagation of Type-I ELMs on JET, W.Fundamenski Outer B-coil Inner B-coil LM11 LM12 LM14 LM15 LM18 LM19 LM21, 22 Soft X-ray Vertical D 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial extent of the SOL density (/t = 0) || G|| +  G = 0 G|| = nv||  D||||n G = nv  Dn || diffusion: tD ~ L||2/D|| || convection: tv ~ L||/Mcs net || transport: t|| = min (tD , tv) ~ tv  diffusion: ln,D ~ (Dt||)1/2  convection: ln,v ~ vt|| 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial extent of the SOL energy (/t = 0) || q|| + q = 0, a = {i,e} q|| = ½(mv2+ 5T)nv||  nc||||T q = ½(mv2+ 5T)nv  ncT || conduction: tc ~ L||2/c|| , c||e >> c||i || convection: tv ~ L||/Mcs net || transport: t|| = min (tD , 5/2tc)  conduction: lq,c ~ (ct||)1/2  convection: lq,v ~ vt|| 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Experimental observation of exponential decay 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

RCP probe + ELMs: MkIIGB, 45490 Type-I ELMs with 8 MW interact with probe upto limiter radius No ELMs observed beyond 20 mm into the limiter shadow Consistent with ~ 4 cm decay length 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Transient evolution of SOL density (/t  0) n/t + || G|| +  G = 0 || G|| = nv||  D||||n  n /t|| G = nv  Dn  dn/dt = 0, d/dt = /t + v/r  /r (D/r) + 1/ t||, Greens function is a convected, gaussian wave-packet 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Slow diffusion (A=1, v=1, D=0.1) no || loss (t|| = 1000) slow diffusion (D= 0.1) strong || loss (t|| = 1) slow diffusion (D= 0.1) 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Moderate diffusion (A=1, v=1, D=1) no || loss (t|| = 1000) mod. diffusion (D= 1) strong || loss (t|| = 1) mod. diffusion (D= 1) 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Strong diffusion (A=1, v=1, D=10) no || loss (t|| = 1000) strong diffusion (D= 10) strong || loss (t|| = 1) strong diffusion (D= 10) 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Characteristic times in the SOL 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Kinetic estimates of || losses 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Kinetic estimates of || losses 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Plasmoid (blob) model of ELM propagation: I (Krasheninnikov,2001) 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Plasmoid (blob) model of ELM propagation: II 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial propagation of Type-I ELMs on JET, W.Fundamenski Core SOLdiv SOLlim D Im(t) tELM tm= ta + Dta-m v In(t) Dta-m t|| tn= ta + Dta-n Dta-n Da(t) ta = tELM + t|| 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Slow (10 kHz) vs. Fast (250 kHz) signals Daslow Dafast I22fast I22slow 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Fast ELM signals: B-coils, soft X-ray, Da Dafast Daslow 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Typical discharge: 12 MW, 2.5 MA/2.4 T 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Typical ELM seen by LM probes Davertical Inmeasured Inohmic Vsupply 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

detail: definition of times & delays DtaFWHM tarise tapeak tnrise tnpeak DtnFWHM 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

I  D0.780.03 r1/2 exp{(8.50.5)r}, r-rlim < 0.3 m Amplitude analysis: I  D0.780.03 r1/2 exp{(8.50.5)r}, r-rlim < 0.3 m I  D0.920.04 r1/2 exp{(22.81.0)r}, r-rlim < 0.1 m 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial propagation of Type-I ELMs on JET, W.Fundamenski 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

ELM Temperature estimate Fitting for peak ELM values, yields Te ~ 25 eV Same for all LM probes The ELM electrons are cold at the plates !!! (at least for high clearance JET discharges with r - rsep > 10 cm) What about the ions ? They are probably hot ! 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Temporal analysis: rise time delays rise < || rise ~ L|| / cs ~ 0.1 - 0.2 msec 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Temporal analysis: peak time delays from the slope, v ~ 950  200 m/s 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Temporal analysis: FWHM widths  ~ 0.18 ms ~ 0.16 m, D ~ 500  100 m2/s 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

SOL density drop vs. lim/sol discontinuity 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

SOL velocity variation vs. lim/sol discontinuity 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

ELM energy flux to the limiters: I 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

ELM radial velocities: summary 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Plasmoid model vs. measured velocities 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Predicted plasmoid size 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Radial propagation of Type-I ELMs on JET, W.Fundamenski Extrapolation to ITER gives v0 ~ 1.0 km/s, 0 ~ 11 cm <v/cs> / (v/cs)ped ~ 0.8 - 1 Hence, need rlim > 14-18 cm for < few % energy to wall 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Inner limiter probes: MkIIA ~ 38000 Type-I ELMs with up to 15 MW; 3 inner probes Have not yet analysed data, but initial examination indicates that... 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski

Inner probe amplitudes smaller & broader: Outer Inner 16/11/2018 Radial propagation of Type-I ELMs on JET, W.Fundamenski