Overview of JET results

1
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

2
JET divertor configuration 2000-2002
2002 onwards Increased triangularity Increased
range of ITB plasma configurations
Up to April 2001

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

3
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

4
ELMs high pedestal density reduces power
transients at ITER shaping
High d 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 d (0.3) J.Ongena, EX/C2-4 A.Loarte,
EX/P1-08
5
Extended/improved data base for Type I ELMs
extrapolation (2 examples)
DWELM scales with nped Loarte,
EX/P1-08 Matthews, EX/D1-1
ELM energy is balanced in/out in JET
even ELM energy distribution ? optimal for ITER
6
Type I- ELM revised extrapolation to 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
7
MHD and kinetic effects a-particle simulation
experiment in ELMy H-mode

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

Multi-MeV acceleration of 120keV 4He beam ions by
3rd harmonic ICRH
Kiptily, NF 42 (2002)
Mantsinen et al., PRL 88 (2002)
J.M. Noterdaeme, EX/W-1
caveat these as are not isotropic in contrast
to DT fusion born as
8
NTM Control sawtooth control by ICRH raises
bN 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 r scaling predicts this to be the case in
  ITER)
• Conversely ICRF heating and current drive near
  q1 modifies sawteeth and raises bN for 3/2 NTM
  onset relative to NBI only case

Sauter, PRL 2002 Hender, EX/S1-2
9
ELMy H-mode Consolidation of ITER reference
operation Beneficial effect of triangularity
Ongena, EX/C2-4
G. Saibene, PPCF 2002
ITER-like plasma shape
Higher edge pressure gradient accessible at high
d (MHD modelling by G.T.A. Huysmans, EFPW 2001)
10
ELMy H-mode / future work Increased
confidence in ITER operation at H1 and n/nGW0.85
JET
AUG
d0.47
d0.29
Ongena, EX/C2-4
Gruber, NF 41 (2001)

• Further ELMy H-mode studies to be driven by
  scientific issues
• understanding experimental differences (details
  of magnetic configuration d, q etc. ELM
  behaviour etc.)
• identifying physics-based scaling parameters for
  high density operation
• interrelation edge/core/details of plasma
  configuration/collisionality

11
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

12
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
13
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 m1, n0 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
14
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/2-1
• Joffrin EX/P1-13

15
Advanced Scenarios Alfvén cascades as
signature of q(r) evolution
Borba, NF 42 (2002)
4
5
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)
5
3
4
5
5
3
4
5
n2
n2
Jaun, CT/P-06, Breizman TH/4-3, Zonca TH/4-4
16
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

Mazon, PPCF 44 (2002) Litaudon, EX/C3-4 Joffrin
EX/P1-13
17
Advanced Scenarios Current Profile Real Time
Control

• Real-time control of plasma current profile
• measurement by polarimetry
• acting on LHCD

Litaudon, EX/C3-4
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A.T. Summary

• Long pulse ITB high performance ITB
  ITER-AT
• JET 53521 t10s JET51976 t6.8s
  Q5
• 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

19
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

20
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

21
Erosion / Deposition shot by shot deposition
measurement with Quartz Microbalance

Quartz monitor
0.1 ?m
80 shots
louvre

• 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

22
Erosion / Deposition Plasma flow in SOL
transports carbon to divertor inner target
Mach Probe
tile analysis QMB
Net Erosion, physical and chemical
Limited Physical Erosion and Deposition
Deposition Chemical Erosion
23
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

24
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 d in an extended
  range of Ip/BT increased power handling)

ITER like antenna / Resonant Double Loop Concept
from ORNL and CEA
25
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/nG0.85 at ITER relevant d(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)

26
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