1 2010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon Association Euratom-cea i a c a r m f c a r e d h i a c a r m f c a r e d h Real Time Control of advanced scenarios for steady-state tokamak operation Xavier LITAUDON CEA-IRFM, Institute for magnetic fusion research (IRFM) CEA Cadarache F-13108 St Paul Lez Durance. France e-mail: [email protected]Courtesy: J.F Artaud, A. Bécoulet, S. Brémond, D. Campbell, J. Ferron, G. Giruzzi, C. Gormezano, E. Joffrin, S. H Kim, D. Mazon, D. Moreau, P. Politzer, T. Suzuki, T. Tala
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Real Time Control of advanced scenarios for steady-state tokamak operation
Real Time Control of advanced scenarios for steady-state tokamak operation. Xavier LITAUDON CEA-IRFM, Institute for magnetic fusion research (IRFM) CEA Cadarache F-13108 St Paul Lez Durance. France e-mail: [email protected]. - PowerPoint PPT Presentation
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12010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Real Time Control of advanced scenarios
for steady-state tokamak operation
Xavier LITAUDONCEA-IRFM, Institute for magnetic fusion research (IRFM)
Courtesy: J.F Artaud, A. Bécoulet, S. Brémond, D. Campbell, J. Ferron, G. Giruzzi, C. Gormezano, E. Joffrin, S. H Kim, D. Mazon, D. Moreau, P. Politzer, T. Suzuki, T. Tala
22010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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OUTLINE
Challenges for continuous operation– continuous tokamak reactor operation
– real time control requirement Real time control of kinetic & magnetic energy
– optimal profile for steady-state & MHD stable profiles
– approaches to profiles control Real time fusion D-T burn control
– burn control with dominant bootstrap and -heating ? Control of core performance with the plasma facing
Worldwide research activity: physics, modelling, technology
52010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Towards a continuous tokamak reactor
self-heating
bootstrap
A scientific and technical challenge
Existence and control of a self-organised plasma state for continuous tokamak operation ?
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Pfusion/Padd DD
~400s
0%
20%
Tore Supra
Q ~ 1
2s
10%
20%
JET
Q ~ 10
400-3600s
70%
10-50%
ITER
Q ~ 30
Continuous
80 to 90%
60-80%
DEMO
duration
JT60-SA
DD
~100s
0%
>60%
62010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Basic standard tokamak parameters
Safety factor q– number of toroidal turns for
one poloidal turn Confinement
– H=/scaling H~1 – scaling = I R2 P-2/3
Stability– q >1 – N = t/(Ip/aB) ≤ 3
Toroidal– t = P/pBtor
– pBtor=B2tor/20
Btor
Poloidal – p= P/pBpol
– pBpol=B2pol/20
Bpol
72010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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STEADY-STATE REACTOR : Optimisation of QDT & Bootstrap current
QDT t B2
Iboot/Ip ½ p= -½ q NBootstrap optimisation
• fusion power + bootstrap high N , , Bsincetp (1+2)
N
• Optimise shaping
• Stability -q & pressure -wall stabilisation
• Confinement
Fus
ion
gain
opt
imis
atio
n
t [%
]
p
10
8
6
4
2
03210
=2
=3
=4
=5lo
w q
95 li
mit
stability limit
Indu
ctiv
e q 95
~3SS q 95
~4-5
82010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Enhanced performance for non-inductive regimes
1
Pla
sma p
ress
ure
0 radius
L-mode
H-mode + internal transport barrier
H-mode
Pedestal
92010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Towards Long Pulse Operation on ITER
Inductive operation – Q 10 Ip~15MA 400s
‘Intermediate’ – Q ~5-10 Ip~12MA 1000s
fully non-inductive – Q~5 Ip~9MA 3000s– Active research activity– Integration of physics &
technology
Inon-inductive/Ip Ibootstrap/Ip
50%
7%
20%
100%
50%
20%
102010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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ITER STEADY-STATE OPERATION
Steady-State operation at Q ~ 5 (P~Padd)
with full non-inductive current drive + optimized current & pressure profiles
Iboot/Ip 50%
N~3, H98(y,2) ~1.5
nl~7x1019m-3
Ti/Te ~ 1
D~3000s
0 1
1
2
5q95~5 (9MA) at high ,
qmin ~ 1.5-2.5
qo-qmin ~0.5
[Gormezano Nuc Fus 2007, Campell Pop (2001), Green et al PPCF 2003 & ITPA steady-state group]
112010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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nHe/ne=6%
N=2
N=3.5
*He/ E =5
Gyro-Bohm scaling
CONTROL OF CORE CONFINEMENT IN STEADY-STATE ITER OPERATION
Control of high confinement for steady state: H/H~20% Q/Q~50% (at Q~5)
favourable effect of density peaking while nHe/ne< 6%
CRONOS-0DITER-AT: Ptot=73MW, Vloop=0
-0.9
0
[Litaudon PPCF 2006]
ITER SS target
122010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Bringing Fusion to its “Reactor Era” requires an innovative programme of “discharge mastering”, combining:– real time control of the magnetic/kinetic
configuration (non-linear and time effects)– real time control of component integrity– high-level algorithms and control schemes– a consistent set of simulation tools:
• first principles (“PFlops”)• integrated modelling (“CPU hours”) • fast simulators (“~ 10 ms”)
The decisive role of real time control
[A. Becoulet & G.T. Hoang PPCF 2008 and Joffrin et al PPCF 2003 ]
132010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Control requirement: plasma scenario
Fusion Power
Plasma Current
Inductive Flux
D-T Fuelling
Plasma Density
-particle Fraction
Additional Power
PF
Res
etA
nd
Rec
oo
l
Po
l. F
ield
Mag
net
izat
ion
Bre
akd
ow
n
Cu
rren
tR
amp
Up
Hea
tin
g
Bu
rnte
rmin
atio
nC
urr
ent
Ram
p D
ow
n
Time(s)
CurrentFlat Top
142010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Example of scenario: JET plasma
JET #67687
152010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Real Time plasma profile reconstruction(EQUINOX code)
[Joffrin et al PPCF 2003, Joffrin et al PPCF 2007 ]
#57336
162010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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S.H. Kim et al, PPCF 2009
Plasma scenario : 15MA H-mode ITER scenario
Tokamak simulation: free-boundary equilibrium (DINA-CH) & transport evolution
(CRONOS)
ITER
172010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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MHD Stability issues & real time control
Edge Localized Modes Damage to Plasma Facing Components
Neo-classical tearing modes Limiting pressure, risk of disruption
Resistive wall modes Limiting pressure
Disruptions Device safety
Fast particle modes Limiting -heating, CD
N
qmin
1 2 30
no wall limit
with wall limit
2/1 NTMs
Tearin
gSn
akes
Fish
bones
Saw
teeth
Hybrid scenarios
Hybrid scenarios
Advanced scenariosAdvanced scenarios
[R. Buttery, EFPW 05]
Necessity for Real Timefeedback control
& localized CD
182010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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PROFILE CONTROL REQUIREMENTS FOR STEADY-STATE OPERATION
[Shimada et al NF 2004, Polevoi et al IAEA 2002]
ITER SS operation above the no-wall limit
at ITER wall position, the marginal is sensitive to details in q and pressure profiles
qmin~2.4, N <3.85
qmin~2.1, N<2.6
qP
ITER
192010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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ITER Heating & Current Drive actuators: FLEXIBILITY for profile Control
NNBI ICRH ECRH LHCD
Heating - electrons
- broad deposition
-70% ions
-central heating
-electrons
-localised
-start-up
-electrons
-localised
-off axis
CD - yes
- broad deposition
-no global CD
- Central (MHD)
-yes
-localised
(MHD)
-yes
-off-axis >0.7
Torque yes no no no
Fuelling small no no no
170 GHz1MeV/D- 5 GHz
20MW/CW20MWCW20MW/CW33MW/CW
40-55 MHz
ITER
202010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Control of a self-organised state ?
[Politzer et al NF 05]
two time scale: fast (blue) & Slow (red) -heating dominant in burning reactor
Actuators
Plasma
212010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Magnetic/Kinetic configuration RT control
222010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Oscillation in confinement observed in steady-state tokamak plasmas
limiting the fusion perfomance
Tore Supra* & DIII-D**(i) non-linear coupling between j & T jLH(j,T), jboot (j,T), (j,T)
(ii) non-linear interplay of heating, CD & MHD s<0, double tearing,
ideal MHD limits …
PROFILE CONTROL REQUIREMENTS
ITER SS extra coupling via -heating(i) non-linear coupling between j & T jboot(j,T), (j,T), P(T)
(ii) non-linear interplay of heating, momentum, CD & MHD P(T), limits,
TAE (-particles), … *Giruzzi et al PRL 03**Politzer et al NF 05
232010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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oscillations of core electron temperature – non-linear interplay
between q-profile, transport and heat sources (and MHD)
Vloop=0 for 6 min, 1 GJ
Neutron (x1010/s)
Zeff ~2
Ti(0) =1.6 keVdensity (x1019m-2)
LH Power (MW)
Transformer flux (Wb)
Te(0) = 4.8 keV
2003
Te(R,t)
Non-linear behaviour in non-inductive regime
[Giruzzi PRL 03; Imbeaux PRL 06; Maget Nuc Fus 06]
TORE SUPRA
242010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Oscillation in bootstrap-dominated regime
[Politzer et al NF 2005]
Time (s)
DIII-D Vl=0 (open
transformer circuit)
1 2 3 4 5
W/W~50% Iboot/Ip~85%N~p~3.3
#119767 #119770
0.5
0.7
0.6
Ip (MA)q95~10
252010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Non-optimal : narrow profiles and steep gradients
Optimal ITB : broad profiles with moderate gradients- MHD stability - broad Jboot and Jtot
- broad ne for reduced impurity accumulation
control of ITB radius, strength & width
ACCESS TO HIGH N OPTIMAL PROFILES ?
p=cstITB width
10
8
6
4
2
0
Pre
ssu
re (
a.u
.)
1.00.80.60.40.20.0normalised radius
ITB radius
262010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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High N requires broad pressure profiles
[Sips IAEA 2004 , Litaudon et al PPCF 2004]
ITPA database
1
2
3
4 N
2 4 6p0/<p>
HybridReversed shearQDB
Stability limit improves with ITB radius and width* control of confinement & q-profile ?
*Lao et al APS 99
272010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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REAL TIME CONTROL OF KINETIC ENERGY
Operation close to the no-wall stability limit while avoiding disruptions
Real time control
of neutral beam heating to match a neutron yield production
Similar results obtained on DIII-D, JT-60U
[G. Huysmans et al., Nucl. Fusion, 1999, C. Gormezano et al FST 2008 ]
JET
t=
282010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Control of electron temperature gradient
[Mazon, Litaudon, Moreau et al PPCF 02]
PLHCD to slow down q(r,t)
PNBI RT controlled by neutron
PICRH RT controlled by s/LTe where LT= T/T
proportional-integral
292010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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RT control of magnetic energy
feedback control for non-inductive operation:
1. Primary voltage Vloop-Vloop, ref
2. PLHCD Ip ref - Ip
3. n//-LHCD Liref- Li
with Li /
(a)
More recently*
n//-LHCD Hard X Ray width representative of LHCD absorbed & J profile
532010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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c ar ed hguard/ICRHlimiter
aux.limiter
hor.plate
lower PSL
roofbaffle
W-coating2006/2007
W-coating until 2003/2004
W-coating2004/2005
W-coating2005/2006
ASDEX
Upgrade
Plasma Facing Components: Wall scenario compatibility, R&D in EU
Effort in EU tokamaks to investigate PFC-scenario issues• Tore Supra: long pulse operation with actively cooled CFC components• ASDEX Upgrade: conversion to all tungsten PFCs complete • JET: installation of beryllium wall and tungsten divertor in 2010
TORE SUPRA
542010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Steady-state scenario and Wall compatibility issue
Control of power & particle exhaust
– Control transient & stationary power loads
– Control of fast particle losses
– Control of particle exhaust & recycling according to fuelling requirements, capacity of Tritium extraction plant & necessary Helium removal
[Litaudon et al EPS PPCF 2007]
simultaneously with
Control steady-state fusion performance
– control of kinetic & magnetic energy (confinement & stability) including impurities
– control fully non-inductive operation
boundary conditions core
plasma
Core conditions
552010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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simultaneous control of transient (ELMs) and stationary power load
[P Lang et al Nucl. Fusion 2005]
Exhaust power controlled by impurity injection:
• noble gases usually chosen• limit heat flux & divertor
temperature to minimize erosion
Feedback control of gas flow:
• radiated power to be actively adjusted
• heat flux to target adjusted in response to variations in loss power (fusion power)
ASDEX Upgrade
562010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Simultaneous real time control of core confinement and heat exhaust
Control of confinement by acting on D2 flux
– Highest density at a given confinement
Control of prad/ptot by acting on Argon flux– reduce divertor heat
load Control matrix from
open loop exp.
[Dumortier P. et al EPS 2004]
572010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Simultaneous control of – Density by gas puffing
near the top of the vessel– Divertor radiation by gas
puffing in divertor – Energy content by NBI
power
Non-diagonal matrix control between actuators & sensors deduced from open loop experiments
Simultaneous real time control of core confinement and heat exhaust
[Fukuda et al FST 2002]
JT-60U
582010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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TORE SUPRA
ICRH antenna IR view
Antenna septum
Current profile n// and PLH
PLH , PICRH Surface Temp.
« Search optimisation » algorithm
Target: broadest current profile
PLH
n//
Start
Optimum found
Simultaneous Profile and Heat load control
[Joffrin Nuc Fus 2007, Barana, Fus Eng Des 07]
592010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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CONCLUSION & FUTURE DIRECTION
New & active field of research that needs a wide range of knowledge from plasma physics to control engineering, experiments & modelling
Major & recent experimental progress to tackle real time control issues for steady-state tokamak operation
Challenging issues for future research direction Integrated modelling towards tokamak simulator ?
– Develop generic methods, modelling of RT diagnostics, control loops, plasma physics, tokamak control system etc
integration and compatibility of the control schemes ?– integrate control of fusion performance & stability with control
of power and particle exhaust during the whole plasma operation demonstration of the controllability of bootstrap-
dominated regime with dominant -heating ?– experiments & modelling
602010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Basic tokamak concept is not stationary
Inductive operation
toroidal coils
shaping coils
magnetic circuit
primary transformer circuit
plasma current (secondary)
622010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Courant autogénéré (bootstrap)
Bt
ne
• courant autogénéré par le plasma
• produit par le gradient de pression (densité et température)
J(r) n(r+) - n(r-) >0
v//
J<0J>0
piégés
théorie transport collisionnel gradient des particules piégés: courant // "amplifié"
par : transfert du moment // aux électrons circulants par
collisions entre électrons piégés et circulants équilibré par le transfert de moment des électrons aux
ions circulants
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CONTROL OF KINETIC ENERGY [1/2]
Density gradients
– Large ne for ITG stabilisation but in contradiction with broad pressure & low impurity accumulation requirements
Ti/Te ratio
– ITER Ti/Te~1 contrary to present day experiments
Plasma impurities injection– ITB expansion observed on DIII-D & JET but core impurity
accumulation should be avoided
642010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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ExB flow shear – Local modification of v with NBI but weak control of v on ITER*
– Control of the diamagnetic term & poloidal rotation with pressure but unfavourable size scaling with * as ExB/ITG *
– positive feedback loops between ExB and pressure
-stabilisation– local control of q (increasing q) and pressure
– positive feedback loop between pressure &
– No size effect (* ) since is the crucial parameters
q-profile– Local reduction of magnetic shear with off-axis non-inductive CD
– Positive feedback with the bootstrap current (no size effects)
– Optimum q-profile for stability & confinement ?
q-control has good prospect for burning plasmas
CONTROL OF KINETIC ENERGY [2/2]
652010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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ITB
ITB: Transport bifurcation
20
10
0
Ti (keV)
3.83.63.43.23.0
R (m)
Review paper : Connors et al NF 2004
Gormezano et al 1996 IAEA
ITB: A layer plasma turbulence reduction
Plasma radius
Litaudon et al 1999 PPCF
Garbet 2004 PPCF
Contour lines of electric potential.
662010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Shear flow stabilisation
Differential plasma rotation: – Break or reduce the radial extend
of the plasma eddies criterion for stabilisation
v
v
r
r
linE
E drdV
672010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Effect of magnetic shear on transport
q & magnetic shear: s = r/q dq/dr s>0
s<0
5
1234
q profile
shear
5
1234
q profile
shearH-mode scenario
Advanced
tokamak scenario 0
-1-2
Normalised radius
Low or negative magnetic shear -twist plasma eddies-Rarefaction of rational surfaces close to s~0-Reduction of the growth rate
682010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Compatibility of ITB with H-mode ?
Combination of Internal & Edge TB lead to: improved confinement improved MHD stability (broad pressure) higher off-axis Jboot
Strong H-mode detrimental to ITB ?:
Large ELMs degrade ITB
JET
[Bécoulet M et al PPCF 2003]
692010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
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Solutions for a successful ‘wedding’ ?
Radiation
[Litaudon et al PPCF 2007]
3
2
1
0
HIPB98(y,2)
15
10
5
0
3.0
2.0
1.0
0.0
PNBI [MW]
IEFCC [kA]
86420
[keV]
Teo
Tio
4
2
0[10
19 m
-3]
9.08.07.06.05.04.0Time [s]
neo
ne ped
D
JET Pulse N°68973
Magnetic conf. Ergodisation
1.5
1.0
0.5
0.0108642
Time [s]
p
D
20
15
10
5
0
PNBI
PICRH
[MW]
PLHCD
4
3
2
1
0
Wdia[MJ]
N
JET Pulse N° 68802
6
4
2
0
[1019
m-3
]
108642Time [s]
neo
D
20151050
PNBI
PICRH
Prad
[MW]
3210
PLHCD [MW]
Ip [MA]
10
5
0
[keV]
Teo Tio
JET Pulse N° 67869
JET
702010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
AssociationEuratom-cea
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Real Time Control of plasma states
[Imbeaux et al EPS 2009]
Te0
PLH
PICRH
ObtainedHot Core requested
MHD (5) detected
TORE SUPRA
Physicist defines the various plasma states (q-profile)
the controller checks whether the plasma is in the reference state and, if not, modifies the LHCD power in the relevant direction:
– state < ref. state increase LHCD
– state > ref. state decrease LHCD
712010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
AssociationEuratom-cea
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Steady-state plasma as a two-cycles non linear oscillator
#33986
Transition from small to giant oscillations due to MHD event when qmin~2
TORE SUPRA
722010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
AssociationEuratom-cea
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Transport Modelling: Bootstrap dominated JET regimes with power upgrade
[Bizarro, Litaudon et Tala NF 2007 & IEEE on plasma science 2008]
Oscillations relaxation
732010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
AssociationEuratom-cea
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Control of ion temperature gradient
5
10
10
20R/LTi
NBI [MW]
No ITB reference
Pulse 58179 (3.0T; 1.8MA, =0.2, n/nG=0.4)
Time [s]
ICRH [MW]LH [MW]
0.01
*Te
0.02
0.030.04
2 4 6 8 10 120
1 H [V]
2 n [m-3] x1019
PNBI controlled by LTi
proportional-integral (PI)
[Joffrin et al PPCF 03]
742010 ITER Summer School, Austin, USA, 31 May - 04 June Xavier Litaudon
AssociationEuratom-cea
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Progress in Active NTM Control
ASDEX Upgrade
• Controlled ECCD Deposition in ASDEX Upgrade, DIII-D, JT60-U