Overview of JET results

IAEA Conference J. Pamela Lyon, 14 October 2002

Overview of JET results

JET EFDA Contributors

presented by J. Pamela

Acknowledgements

Staff and management from EFDA Associates involved in the JET workprogramme, in particular the JET Task Force Leaders and the Operator of the facility (UKAEA)

European Commission International collaborators: U.S.A. and Japan


JET divertor configuration 2000-2002

Septum removed by remote handling: Mk-IIGB to Mk-IISRP

Up toApril 2001

2002onwards

Increased triangularity

Increased range of ITB

plasma configurations


Content of the talk

H-mode ELMs physics / ELM extrapolation to ITER MHD and kinetic effects on H-mode performance H-mode performance / consolidation of ITER reference scenario

Advanced Tokamak AT Physics AT performance Real time control

Erosion and co-deposition Future plans


ELMs: high pedestal density reduces power transients at ITER shaping

High and high npedestal leads to softer and less frequent ELMs(mixed type I - type II)

Other “recipes” for access to softer ELMs:- impurity seeding- high Pin/PLH at moderate (~0.3)

J.Ongena, EX/C2-4 A.Loarte, EX/P1-08


Extended/improved data base for Type I ELMs extrapolation (2 examples)

WELM scales with *ped

Loarte, EX/P1-08 Matthews, EX/D1-1

4 6 8 10

ne / 1019m -3

0

0.02

0.04

0.06

0.08

Wta

rget

/ W

pla

sm

a

to ta linnerouter

ELM energy is balanced in/out in JET

even ELM energy distribution

optimal for ITER


The improved/extended data base allows revised predictions assuming JET data extrapolate to ITER:

Tolerable ELMs (C or W) Wmax = 4 to 19 MJ

Type I-ELM size predictions WELM = 10 to 20 MJ

=> hope that Type I ELMs may be tolerable

Matthews, EX/D1-1 Loarte EX/P1-08

Type I- ELM revised extrapolation to ITER


MHD and kinetic effects -particle simulation experiment in ELMy H-mode

• evidence from emission from nuclear reaction 9Be(,n)12C • fast ’s provide up to 80-90% of plasma heating • long sawteeth stabilised by s leading to NTMs

Multi-MeV acceleration of 120keV 4He beam ions by 3rd harmonic ICRH

caveat: these ’s are not isotropic in contrast to DT fusion born ’s J.M. Noterdaeme, EX/W-1Mantsinen et al., PRL 88 (2002)

Kiptily, NF 42 (2002)


NTM Controlsawtooth control by ICRH raises N NTM onset

• Long period sawteeth (due to ICRH) allow NTMs to be destabilised at any BT

• used to extend parameter domain towards ITER

• typical H-modes in JET are metastable to NTMs (and * scaling predicts this to be the case in ITER)

• Conversely ICRF heating and current drive near q=1 modifies sawteeth and raises N for 3/2 NTM onset relative to NBI only caseSauter, PRL 2002 Hender, EX/S1-2


ITER-like plasma shape

ELMy H-modeConsolidation of ITER reference operationBeneficial effect of triangularity

G. Saibene, PPCF 2002

Ongena, EX/C2-4

Higher edge pressure gradient accessible at high (MHD modelling by G.T.A. Huysmans, EFPW 2001)


HH

AUGJET

Further ELMy H-mode studies to be driven by scientific issues :- understanding experimental differences (details of magnetic configuration ,

q etc.; ELM behaviour etc.)- identifying physics-based scaling parameters for high density operation- interrelation edge/core/details of plasma configuration/collisionality

=0.29=0.47

ELMy H-mode / future workIncreased confidence in ITER operation at H~1 and n/nGW>0.85

Ongena, EX/C2-4Gruber, NF 41 (2001)


Content of the talk





Advanced Tokamak reliable tuning of shear reversal by LHCD providing easy access to ITBs

Challis PPCF 44 (2002)Hawkes PRL 87 (2001)

Litaudon, EX/C3-4


Advanced Tokamak Current Hole observation and modelling

20-40 cm wide core region has j(r)=0 (error bars ± 10-20 kA)

Modelling: Although off-axis co-LHCD is sufficient to drive negative current near axis, repetitive m=1, n=0 modes would ‘clamp’ current to zero

Hawkes, PRL 87 (2001), Huysmans, PRL 87 (2001), Stratton, PPCF 44 (2002)Miura EX/C3-1Ra, Stratton EX/C3-1Rb


Advanced Scenarios link between rational q surfaces and ITBs

Transport barriers appear/develop when qmin crosses rational q surfaces

The time when qmin crosses rational surfaces is confirmed by the excitation of Alfven cascades

Garbet TH/2-1Joffrin EX/P1-13

Pulse 51573. JET ITB criterion from electron temperature (ECE)

*T

0.014

0.016

0.018

0.020

0.022

n=1 m=2 mode

4.5 5 5.5 6 6.5 7 7.5

3.2

3.3

3.4

3.5

3.6

3.7

Time (s)

s>0

s<0

q=2Major Radius [m]

5MW ICRH + 11.5MW NBI

MHD n=1 component [a.u.]

qmin

‘narrow’ ITB in thes<0 region

q=2 locationfrom the MHDanalysis [38]


3

n=2

45

534

45

55

n=2

Alfvén Cascades observed in ITB plasmas (c.f. JT60-U) and modelled

Indication of q(r) evolution from TAE antennas:

diagnostic for qmin evolution in ITB plasmas (use of TAE antennas demonstrated for monotonic q profiles)

Jaun, CT/P-06, Breizman TH/4-3, Zonca TH/4-4

Advanced Scenarios Alfvén cascades as signature of q(r) evolution

Borba, NF 42 (2002)


Advanced Scenarios Feasibility Demonstration of Pressure Profile Real Time Control

Real time feedback loop on neutron rate controlled by NB Te-profile controlled by ICRH

3.0

2.0

1.0

0

6

4

2

01.2

0.8

0.4

0

12108642Time [s]

15

10

5

01.2

0.8

0.4

0

Active control

Ip[MA]

#53697

PNBI

PICRH

Vs [V]

PLHCD[MW]

MW

1016 neutron/s

s/Lte (x10-2)

Reference

Reference

Mazon, PPCF 44 (2002)Litaudon, EX/C3-4Joffrin EX/P1-13


Advanced Scenarios Current Profile Real Time Control

Real-time control of plasma current profile measurement by

polarimetry acting on LHCD

Litaudon, EX/C3-4


A.T. Summary“Long pulse ITB” “high performance ITB” ITER-AT[JET #53521 t=10s] [JET#51976 t=6.8s] Q=5

H H (IPB98y-2) 1 1.9 >1.5

H ITER 89 L-P 2.1 3.3

N 1.7 2.4 >3.0

nel/nGreenwald 0.5 0.35 0.6-1

INon-Inductive/Ip 90% 55% 100%

Iboot/Ip 50% 40% >60%

q95 5.5 4.9 4.5

Prad/Ptot 23% 15% 75%

/E. 27 2 >100

Edge type III ELMs type III ELMs soft ELMs

=> progress … but still significant efforts needed: higher density / long pulse high

performance / impurity control / simultaneous pressure and current profile control


Content of the talk





Erosion / Deposition Tile Analysis (MkII-GB divertor)

Analysis of tiles removed during Shutdown 2001: clear deposition in inner divertor (co-deposited layers) almost no deposition in outer divertor Deposited material is mostly from main chamber erosion

=> Confirm results from tile analysis with the more open MkII-A divertor


louvre

Quartz monitor

Measured deposition rate much lower than concluded from Deuterium-Tritium experiments in 1997 : possible reasons

- strike point position (identified to be very important )

- lower density plasmas with larger ELMS in 1997- reduced operating T: V-vessel from 300 to 200ºC tiles from 200 to 100ºC (effect tbc)

- QMB at 100ºC while divertor louvres are water cooled V.Philipps, EX/P5-08

0 1x1025 2x1025 3x1025 4x1025

0

4x1017

8x1017

1x1018

To

tal d

epo

siti

on

(C

/cm

2 ) Total ion flux during exposure (inner)

0.00

0.04

0.08

0.12

To

tal c

arb

on

on

lou

vre

area

(g

)

0.1 m

80 shots

Erosion / Deposition shot by shot deposition measurement with Quartz Microbalance


Limited Physical Erosion

and Deposition

DepositionChemical Erosion

Net Erosion,physical and

chemical

Erosion / Deposition Plasma flow in SOL transports carbon to divertor inner target

Mach Probe

tile analysisQMB


Content of the talk





Near Term Plans Experimental Campaigns until February 2004,

including a Trace Tritium Campaign 2004 shutdown:

new/upgraded diagnostics ICRH ITER-like antenna => High Power Density

ICRH coupling / ELM-resilience modified divertor (ITER-like in an extended

range of Ip/BT ; increased power handling)

ITER like antenna / Resonant Double Loop Concept from ORNL and CEA


Conclusion ELMy H-mode

revised Type I ELMs predictions / hope that Type I ELMs be tolerable on ITER possible paths to alternate / softer ELMy regimes compatible with high HH

progress in NTM physics and control (sawtooth / ICRH) new tool for alpha particle studies available (4He acceleration by ICRH) consolidation of ITER operating scenario HH ~1 and n/nG>0.85 at ITER relevant (~0.5),

q95(~3) in relevant Zeff range (1.5-2.0) Advanced Modes

LHCD provides easy and reliable access to Reversed Shear and control of off-axis current in long pulses

Current Holes observed in R.S. / Transport & MHD models developed Rational q surfaces play a key role in ITB formation/development Alfvèn cascades in R.S. plasmas: promising tool for q(r,t) diagnostic Real Time control of pressure profile demonstrated Real Time control of current profile demonstrated

JET remains a key asset with unique features in preparation of ITER Operation (ITER scenarios / test of ITER auxiliaries prototypes)


JET papers at this confrence LOARTE "Type I ELM energy and particle losses in JET ELMy H-modes and implications for ITER", EX/P1-08

MATTHEWS .,"Steady state and transient power loads in JET", EX/D1-1

RAPP "Reduction of divertor heat load in JET ELMy H-modes using impurity seeding techniques", EX/P1-09

PARAIL "Integrated Modelling of JET H-mode Plasmas with type-I ELMs", TH/P3-08

KOSLOWSKI "Observation of Pre- and Postcursor Modes of Types I ELMs on JET", EX/P1-14

LITAUDON "Progress towards steady state operation and real time control of ITBs in JET", EX/C3-4

HENDER "Sawtooth, Neo-Classical Tearing Mode and Error Field Studies in JET", EX/S1-2

ONGENA "Towards the realization on JET of an integrated H-Mode scenario for ITER", EX/C2-4

TESTA "Experimental Study of the Stability of Alfven Eigenmodes on JET", EX/P1-17

NOTERDAEME "Heating, current drive and energetic particles studies on JET ...", EX/W-1

MANTICA "Transient Heat Transport Studies in JET Conventional and Advanced Tokamak Plasmas", EX/P1-04

GARBET "Micro-stability and Transport Studies of Internal Barriers in JET", TH/2-1

JOFFRIN "Internal Transport Barrier triggering by rational magnetic flux surfaces", EX/P1-13

DUX "Impurity transport in internal barrier discharges on JET", EX/C3-5Ra

PHILIPPS "Recent results on long term fuel retention in JET and TEXTOR and predictions for ITER", EX/P5-08

SUTTROP "Parameter similarity studies in JET, ASDEX Upgrade and ALCATOR C-Mod", EX/P5-07

HIDALGO "Experimental evidence of fluctuations and flows near marginal stability ...", EX/C4-4

STRATTON "Equilibria and Stability of JET Discharges with Zero Core Current Density", EX/C3-1Rb

(see talk by Miura, EX/C3-1Ra)

CASTALDO "Transport barriers produced in JET discharges by ion Bernstein waves", post-deadline

JAUN "Collective modes and Fast Particle Confinement in ITER", CT/P-06

ASAKURA "Studies of ELM heat load, SOL flow and carbon erosion ..." , CT/P-01

BREIZMAN "Alfven Eigenmodes in Shear Reversed Plasmas", TH/4-3

Overview of JET results

Documents

iter shapinghigh d

iter operation

elmy hmode evidence

iter typical hmodes

elm revised extrapolation

jet data

elms extrapolation

elm behaviour