Overview of JET Results
Francesco Romanelli
on behalf of JET-EFDA Contributors
22nd IAEA Fusion Energy Conference
13 October 2008, Geneva, Switzerland
F. Romanelli 1 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
• The JET programme is strongly focussed on
the consolidation of the ITER design choices
and the preparation of ITER operations.
ITER
pellet
ITER-like Ion Cyclotron
antenna
F. Romanelli 2 (31) 22nd IAEA FEC
High frequency
pellet injector
Geneva, Switzerland
JET
ITER-like wall
project
13 October 2008
Number of JET discharges
with
PNB>20MW
Number of JET
pulses with P ≥ 20 MW
• Very good performance of
auxiliary heating systems
– Neutral beam enhancement
capabilities (increase in
power up to 34MW)
confirmed on the test bed.
157
160
143
120
100
80
65
60
40
20
25
24
21
2
0
0
1994
1996
1998
0
0
0
0
2000
0
2002
10
2004
2006
2008
Year
• 50 new diagnostics completed or
under completion (some of them
specific ITER developments)
F. Romanelli 3 (31) 22nd IAEA FEC
Injected deuterium power (MW)
Number of pulses
140
2.5
2.2 MW
125kV/65A PINI (Chequerboard)
2.0
1.5
10Gbytes
per shot
1.0
125 kV
NBI
180
0.5
130kV/56A PINI (Supercusp)
0.0
40
60
80
100
120
JET raw data
140
Beam voltage (kV)
Predicted deuterium neutral beam power of a
125kV/65A chequerboard PINI
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 4 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 5 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
ELM characterization and control
Divertor material damage sets the limit on allowable ELM energy losses
ITER min.
requirement
W
Predicted ELM
size in ITER
CFC
ELMs must be controlled
maintaining good H-mode
confinement!
F. Romanelli 6 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
MA
ELM and pedestal characterization at high
currents up to 3.8MA
JET can investigate ELM
and pedestal conditions
of direct ITER relevance
Beurskens EX/P3-4, Tue. PM
MW
ITER domain
MJ
High-resolution
Thomson scattering
F. Romanelli 7 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Type I ELM power loads on PFC
Pre-ELM separatrix
Heat flux (MW/m2)
Filaments
Δt = 0 µs
Δt = 85 µs
Δt = 170 µs
Δt = 255 µs
Δt = 340 µs
Δt = 425 µs
Quasi-toroidal
mode numbers
of ~ 4 to 12
consistent with
previous
observations on
AUG
Fundamenski/Eich EX/43RA/RB, Wed. PM
Target coordinate (m)
Time resolved IR measurements of heat
loads on divertor target
• Model of ELM filament parallel energy loss (W. Fundamenski PPCF 2006) in good
agreement with measurements
• Fraction of ELM energy deposited on the main chamber tiles ranges from 10 – 5 %,
decreasing with relative ELM size
• Suggests that mitigated ELMs on ITER (1 MJ) not a problem for main chamber tiles
F. Romanelli 8 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
ELM mitigation with magnetic perturbations
Magnetic perturbation
⇒ Edge stochastic magnetic field
⇒ edge pressure gradient kept below threshold
In-vessel coils in DIII-D and ITER
Ex vessel coils (error field
correction coils) in JET
Advantage: large toroidal mode number
spectrum of the perturbation .
Advantage: External Coils, more
relevant for reactor application.
Limitation: Internal coils, subject to
neutron radiation => reactor relevance?
Limitation: low toroidal mode number
spectrum of the perturbation
F. Romanelli 9 (31) 22nd IAEA FEC
Geneva, Switzerland
13 October 2008
ELM mitigation with external magnetic perturbation field in
JET
#69564
•
ELM frequency increased form 30Hz to
120Hz and ELM energy loss reduced from
7% to below noise level (~2%). Reduction
in ELM peak heat fluxes and carbon
erosion
•
Electron density decreases (pump out)
•
Electron and ion temperatures increase
(core and edge)
•
Reduction in the thermal energy
confinement but no change compared to
H-mode scaling
Coil current
kAt
Density
Temperature
I =keV
1.5 MA; B = 1.78 T; q ~ 4.0; δ ~ 0.45
Confinement normalised
to H-mode scaling
Dα emission
•
Liang EX/4-2, Wed. PM
F. Romanelli 10 (31)
Wide range in q95 (4.8 – 3.0) with n = 1, 2
∀ βN up to ~2.9 (no locked mode excited by n=1 field)
e
• IAEA FEC
22nd
Geneva, Switzerland
13 October 2008
ELM pacing using the vertical stabilisation
controller
Coil
voltage
Effect of a kick
70427@16.5
Dα emission
Plasma
Energy
• Successful pacing of ELMs demonstrated
• ELM frequency increased by at least a factor of 5
• Plasma energy not affected by kicks
Dα emission
Plasma
energy
F. Sartori EPS 2008
F. Romanelli 11 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Highly radiative N seeded ELMy H-mode with type
III ELMs extended to IP=3.25MA
Strong D & N2 fuelling
Both divertor legs detached
• Radiated fraction~ 70%
• H98=0.82
• ne=1.1x1020 m-3 ≈ Greenwald
density
• Wdia=7.6MJ
• Small type III ELMs
• fELM~1kHz
• Zeff <1.4
Scenario extrapolates to
17MA Q=10 on ITER
Rapp EX/4-4RB, Wed. PM
F. Romanelli 12 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 13 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Hybrid scenario with improved
confinement
Hybrid scenario in ITER requires up to 50% increase over the H-mode
confinement
In 2008 JET studies the effect of
broader q profile on confinement
Strong current ramp-up then ramp down produces
significant q profile broadening
74825 & 74826 (BT=2T)
Ip [MA]
EFIT reconstruction with
MSE
PNBI
[MW]
+ MHD markers
Time [s]
q
EFIT reconstruction with
MSE + MHD markers
R [m]
F. Romanelli 14 (31)
Energy Confinement time (s)
H98(y,2) = 1.5
2008
DIII-D
JET
(β <2.2)
AUG
NTH
(β
<3.2)
H98(y,2) = 1
H-mode
confinement scaling (s)
(β <2.7)
Other factors affecting confinement include:
• rotation
Joffrin EX/1-4RA, Tue. AM
• pedestal
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Access to high normalised pressure
Two experimental lines followed at q95=5, δ~0.35-0.5, n/nG~50-80%:
- BT=1.8T, high βN scenario for
stability explorations
T
- B =2.7T scenarios for exploitation
after the JET upgrades
• High βN (~3) maintained for a
resistive time
• 60%-75% of non-inductive
current
• Confinement 20% above Hmode
Rimini EX/1-2, Tue. AM
F. Romanelli 15 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 16 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Test of the JET ITER-like ICRH antenna
• ITER-relevance
Nightingale FT/4-5RA, Sat. AM
Lower half
Coupled power (MW)
Upper half
– High power density (8MW/m2)
– Tolerant to fast coupling changes (ELMs)
– Equivalent matching complexity (4 resonant
double loops)
Antenna Front
Time
F. Romanelli 17 (31)
22nd IAEA FEC
3.8 MW coupled so far in
L mode plasmas with full array
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 18 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Toroidal field ripple studies in JET
• JET
JET results suggests δBT < 0.5% in ITER
required to achieve QDT=10 goal
& reduce uncertainty
on confinement
extrapolation.
1.3
• 32 coils
 Intrinsic ripple δ ~ 0.08%
• Separate control of odd/even 1.2
coils allows to control ripple
1.1
• Ripple scan in the range
BT
Confinement 1.0
time
normalized to 0.9
H-mode
scaling
0.8
δ ~ 0.08%-1%
and density scan
• 2.6MA/2.2T
• Neutral Beams only
•Saibene
FastEX/2-1,
particle
up to
20%
Tue.losses
PM, De Vries
EX/8-3
F. Romanelli 19 (31)
22nd IAEA FEC
0.7 with ferritic insets
ITER
w/o ferritic insets
Ripple (%)
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 20 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Heat loads on PFCs during disruptions
Time scale for energy deposition during disruptions crucial for
lifetime of ITER PFCs
Thermal quench: High heat loads on plasma facing components (PFCs)
•
During thermal quench on JET, energy deposition timescale (td) measured to be 2-7
times longer than that of the plasma thermal energy collapse (tc)
tc
td
Peak heat load on
upper dump plate
Arnoux EX/7-2RA, FRI. AM
t-tth-quench (ms)
Current quench: Large electromagnetic forces on vacuum vessel and in-vessel
components (halo and eddy currents)
•
First halo current density measurements in JET observed to be consistent with heat
load footprint on the upper main chamber PFCs
Riccardo EX/7-2RB, FRI. AM
F. Romanelli 21 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Material migration in JET
JET DTE1 campaign (1997)
JET MKII A
Observations from recent experiments
First wall
 Main chamber is primary erosion source
 Transport by SOL flows to inner divertor
inner
louvre
Divertor
 Inner divertor is a net deposition zone
Erosion/deposition determined by magnetic
• 6 out of 35g injected tritium retained
configuration (line-of sight), power loads at strike-
• Major part of retained tritium is co-
points (ELMs), and local surface conditions (layers)
deposited with carbon in remote areas of
 Be re-erosion is low in comparison to C
the inner divertor (louvre)
 Transport of C to remote areas
Brezinsek, PPCF 2008; Kreter, PRL 2008
 Strike points sweeps enhance C migration
These observations can explain the large C deposition and T retention in DTE1
F. Romanelli 22 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Fuel retention studies using gas balance
Fuel retention studied in a series of repetitive and identical discharges to minimise the
contribution from previous experiments (history), achieve a high accuracy (~1.2%)
Pulse
type
Injection
(Ds-1)
Heating
Long term
Divertor
phase (s) retention (Ds-1) phase (s)
Long term
-1
retention (Ds )
L-mode
~1.8×10
81
2.04×1021
21
126
1.27×10
Loarer, PSI 2008
- Long term retention increases from L-mode to H-mode
Increased C erosion and transport due to increased recycling and effect of
ELMs  enhanced C erosion  enhanced co-deposition and retention
Confirm the strong concerns about fuel retention in a carbon tokamak
Future Beryllium wall and Tungsten divertor in JET
should confirm low retention properties
F. Romanelli 23 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 24 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
• Existence of ITG
threshold verified
experimentally
• Ions very stiff in
low rotation
plasmas while
less stiff in high
rotating plasmas
Normalised ion heat flux at r/a=0.33
Ion heat transport studies
threshold
Mantica EX/2-4, Tue. PM
F. Romanelli 25 (31)
R/LTI
Ryter EX/P5-19, Wed. PM
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Momentum transport studies
• Steady-state analysis cannot separate the diffusivity and pinch
terms in the momentum flux
=> modulation of rotation is needed
By modelling and fitting the
amplitude and phase of the
modulated toroidal rotation
together with the steady-state,
the momentum diffusivity and
pinch can be determined.
• Inward momentum pinch velocity of about 20m/s experimentally
found on JET
φ
•
i
Tala EX/3-3, Wed. AM
Prandtl number χ /χ is
around 1, in agreement
with present
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
F. Romanelli 26 (31)
OUTLINE
• Impact of ELMs on plasma facing components and their
active mitigation
• Developments of ITER hybrid/ advanced scenarios
• Test of the ITER-like antenna
• Effect of toroidal field ripple on H-mode plasmas
• First wall power and particle loading
– Head loads on PFCs from disruption
– Material erosion, migration & fuel retention
• Stability and transport studies
• Outlook
F. Romanelli 27 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
Enhancement Programme 2 in the
procurement phase
ITER
ITER-like wall
Neutral Beam Enhancement
Plasma Control Upgrade
High-Frequency
Pellet Injector
Diagnostics
ICRH horizontal private limiter
W coating at MEdC
JET
Bulk tungsten tile
F. Romanelli 28 (31)
22nd IAEA FEC
Extended Octant 1 boom
Geneva, Switzerland
13 October 2008
Next 10 years schedule
Original investment in and subsequent
upgrades of the JET Facilities (M€ of year)
1977-81
2009
1983
2010
2011
2012
2013
2014
2015
2016
2017
2018
1985
1987
Construction
ITER
1989
1991
Construction
EVEDA
IFMIF
1993
During the next few years JET will
be the only device of its class in the world.
JET will be the best machine to prepare the ITER
joint exploitation.
DT
1995
1997
1999
experiment
2001
2003
2005
Shutdown
JET
JT60SA
EP2 exploitation
Commissioning and
Joint experiments
Other supporting activities (physics and technology)
2007
Construction
2009
2011
Launched
100M€
F. Romanelli 29 (31)
22nd IAEA FEC
Geneva, Switzerland
Proposed
13 October 2008
25 years of research at JET
F. Romanelli 30 (31)
22nd IAEA FEC
Geneva, Switzerland
13 October 2008
JET contributions at this conference
TUESDAY
AM
THURSDAY
AM
F.G. RIMINI
(EX/1-2)
R.J. BUTTERY
(IT/P6-8)
E. JOFFRIN
(EX/1-4RA)
M. GONICHE
(EX/P6-22)
J. ONGENA
(EX/P6-33)
V. PARAIL
(IT/P6-7)
(IT/P6-14)
TUESDAY
G. SAIBENE
PM
(EX/2-1)
P. MANTICA
(EX/2-4)
P.B. SNYDER
M.N.A. BEURSKENS
(EX/P3-4)
THURSDAY
WEDNESDAY
T. TALA
AM
(EX/3-3)
WEDNESDAY
PM
PM
I.T. CHAPMAN
(TH/4-1)
N.N. GORELENKOV
(TH/5-2)
FRIDAY
AM
Y. LIANG
(EX/4-2)
G. ARNOUX
(EX/7-2RA)
W. FUNDAMENSKI
(EX/4-3RA)
V. RICCARDO
(EX/7-2RB)
T. EICH
(EX/4-3RB)
A.C.C. SIPS
(IT/2-2)
J. RAPP
(EX/4-4RB)
V. KIPTILY
(EX/P8-8)
P. LANG
(EX/4-5)
A.Yu. DNESTROVSKIJ
(TH/P8-23)
F. RYTER
(EX/P5-19)
D. Del-CASTILLO-NEGRETE
(TH/P8-38)
M. MASLOV
(EX/P5-20)
FRIDAY
PM
P.C. De VRIES
(EX/8-3)
Y.Q. LIU
(TH/P9-26)
SATURDAY
M. NIGHTINGALE
F. Romanelli 31 (31)
22nd IAEA FEC
Geneva, Switzerland
AM
(FT/4-RA)
13 October 2008