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Doctorate in Fusion Science and Engineering 06 Oct. 2010 1 (34)
Toroidal rotation in JET and Tore Supra Tokamaks
Toroidal rotation in JET and Tore Supra Tokamaks
João Bernardo
Supervisor: Dr. Santiago Reyes Cortes
Co-supervisor: Dr. João Pedro Bizarro
JET:Y. Andrew, K. Crombé, S. Reyes Cortes,
G. Saibene, J. Lönnroth, T.M. Biewer,
J.Ferreira, N.C. Hawkes, I. Jenkins, E. de
la Luna, D. McDonald, I. Nunes, A. Salmi
Tore Supra:P. Hennequin, L. Vermare, N. Fedorczak, Ö. D.
Gürcan, E. Trier, N. Stuyck, C. Fenzi, J. Gunn,
P. Monier-Garbet, C. Bourdelle, P. Ghendrih,
X. Garbet
Doctorate in Fusion Science and Engineering 06 Oct. 2010 2 (34)
- JET / Tore Supra
- NBI
- Charge-eXchange Recombination Spectroscopy (CXRS)
- Results
- Future work and perspectives
Outline
Doctorate in Fusion Science and Engineering 06 Oct. 2010 3 (34)
Main features
JET / Tore Supra
JET Tore Supra ITER
Operation 1983 1988 -
Design (early/current) Limiter / Divertor Ergodic / Limiter Divertor
Major plasma radius 3.0 m 2.25 m 6.2 m
Minus plasma radius 0.90 m 0.70 m 2 m
Plasma Volume 100 m3 / 80 m3 25 m3 ~800 m3
Toroidal magnetic field 4 T 4.5 T 5.3 T
Plasma current 7 MA 1.7 MA 15 MA
Potential duration of the discharge
Few seconds 390 s (record)1000 s (predicted)
~400s -> Steady state
Q ~1 ~0 10
Doctorate in Fusion Science and Engineering 06 Oct. 2010 4 (34)
JET / Tore Supra
http://irfm.cea.fr/gb/iter/iter02.htm
Doctorate in Fusion Science and Engineering 06 Oct. 2010 5 (34)
Joint European Torus
Currently the only machine capable of operating with D-T plasma
Primary task : prepare construction and operation of ITER- Act as a test bed for ITER technologies and plasma operating scenarios
From 2011 onwards : FW will be of Be and W
Auxiliary heating system:Neutral Beam Injection (NBI) of 35 MWIon Cyclotron Resonance Heating (IRCH) of 10 MWLower Hybrid Current Drive (LHCD) of 7 MW
A high frequency pellet injector for plasma refuelling and for ELM pacing studies. A massive gas injection valve for plasma disruption studies.
Remote handling facilities
JET / Tore Supra
Doctorate in Fusion Science and Engineering 06 Oct. 2010 6 (34)
Superconducting field coils cooled by superfluid helium 1.8K (2)Actively cooled PFCs (water) (7)Long pulse LHCD and ICRH (14 & 15)
Was equipped with a ergodic divertor and discrete set of limitersNow equipped with a Toroidal Pump Limiter (8)
JET / Tore Supra
New generation of limiters (CIEL project in 2000) is now capable of extracting a total of 15 megawatts of power transferred by plasma particles (maximum flux density of 10 MW/m2)
7m2 "limiter" ring with:
-576 horizontal actively cooled fingers
Doctorate in Fusion Science and Engineering 06 Oct. 2010 7 (34)
JET / Tore Supra
Doctorate in Fusion Science and Engineering 06 Oct. 2010 8 (34)
- JET / Tore Supra
- NBI
- Charge-eXchange Recombination Spectroscopy (CXRS)
- Results
- Future work and perspectives
Outline
Doctorate in Fusion Science and Engineering 06 Oct. 2010 9 (34)
NBI JET / Tore Supra
Tore Supra [1]:
Neutral Beam Injection for diagnostic purpose : PDNBI ~ 700kW
JET plasma heating systemsJET plasma heating systems
• JET has 16 JET has 16 PPositive ositive IIon on NNeutral eutral IInjectors njectors (PINIs) distributed in two (PINIs) distributed in two NNeutral eutral IInjector njector BBoxes (NIB)oxes (NIB)
NIB4:NIB4: 8 PINIs 8 PINIs (4 tangential/4 (4 tangential/4 normal)normal)
NIB8: NIB8: 8 PINIs 8 PINIs (4 tangential/4 (4 tangential/4 normal)normal)
• Maximum injected power (DMaximum injected power (D22): ): ~~24 MW24 MW
• Beam pulse length : Beam pulse length : 10 s 10 s (at high power)(at high power)
• Neutral Beam Enhancement (NBE) project will give ~35MW of Total Power and double the pulse length.
[1] A. Simonin et al., Rev. Sci. Inst., 73, 2886 (2002)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 10 (34)
- JET / Tore Supra
- NBI
- Charge-eXchange Recombination Spectroscopy (CXRS)
- Results
- Future work and perspectives
Outline
Doctorate in Fusion Science and Engineering 06 Oct. 2010 11 (34)
CXRS – Diagnostic principle
Doctorate in Fusion Science and Engineering 06 Oct. 2010 12 (34)
CXRS – Diagnostic principle
Beams
Vessel
SOL -
Cold/not rotating
Lines of Sight (LOS)
Active -
Hot/rotating
Passive -
Warm/rotating slowly
Doctorate in Fusion Science and Engineering 06 Oct. 2010 13 (34)
CXRS - JETIn
ten
sity
P
h m
-2 s
r-1 n
m-1 s
-1
Pixel
CVI-CX
Active Charge eXchange (ACX)CVI passive
Passive Charge eXchange (PCX)
BeII CIII edge line
Eleonora talk
H0 + Az+ → H+ + A*(Z-1)+
D0 + C6+ → D+ + C5+ Transition between Rydberg states Δn=1 (n=8 → 7) 5290.6Å
Doppler broadening → Ti
Doppler shift → vφi/vθi
Doctorate in Fusion Science and Engineering 06 Oct. 2010 14 (34)
CXRS - JETIn
ten
sity
P
h m
-2 s
r-1 n
m-1 s
-1
Pixel
CVI-CX
Active Charge eXchange (ACX)
Ti
λobs
λT
Vφ/θ
Doctorate in Fusion Science and Engineering 06 Oct. 2010 15 (34)
- JET / Tore Supra
- NBI
- Charge-eXchange Recombination Spectroscopy (CXRS)
- Results
- Future work and perspectives
Outline
Doctorate in Fusion Science and Engineering 06 Oct. 2010 16 (34)
Results - JET
Plasma operation with Type-I ELMs to reach Q=10 for ITER [2].
Improve the understanding of the physics of ELMs
Control Type-I ELMs
- DIII-D [3]
- TCV [4]
- ASDEX-Upgrade [5]
Reports from JT-60U [6] have shown that neutral beam injection (NBI) in counter-current direction alters vφ decreasing the fELM.
Therefore, further understanding of ELM behavior and the relationship with toroidal velocity is relevant for ITER
[2] ITER Physics Basis, Nucl. Fusion, 47, S18 (2007) [3] T.E. Evans et al., PRL, 92, 235003 (2004) [4] A.W. Degeling et al., PPCF, 45, 1637 (2003) [5] H. Urano et al., PPCF 45, 1571 (2003) [6] Y. Sakamoto et al., PPCF, 46, A299 (2004) [7] P. de Vries et al., Nucl. Fusion, 48, 035007 (2008) [8] H. Urano et al., Nucl. Fusion, 47, 706 (2007)
Effect of vφ on fELM.
TF ripple breaks the axisymmetry of the magnetic field, enhancing particles losses of fast and thermal ions [7,8] affecting vφ.
JET δr = 0.08-3% ITER δr ~0.5% (FI compensation)
Varying δr
Doctorate in Fusion Science and Engineering 06 Oct. 2010 17 (34)
Results – JET (TF ripple)
Ripple in tokamaks can be compared to a ripple on the water surface
Finite number of coils
JET has 32 TF coilsδr varied by configuring different currents to the odd and even set of coils
δr = [Bmax - Bmin)] / [Bmax + Bmin)]
magnetic field along the circle for which the major radius R and the vertical coordinate Z are constant
δr ~ 0.08%-3%
contour plot of δr with the current ratio of odd/even = 0.52 (δr = 1%)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 18 (34)
Results – JET (TF ripple)
TRANSPORT AND LOSSES INDUCED BY TF RIPPLE
The toroidal field ripple enhances the transport of fast ions by modifying their guiding centre orbit. Two mechanisms:
- Ripple-trapped transport
- Ripple-banana diffusion
Operational boundaries depends on δr, plasma shape and on plasma parameters (ne and Ip)
T. Johnson et al., “HALEKAR Modelling of Fast Particle Transport and Losses with TF Ripple in JET”, 10th IAEA proceedings
Doctorate in Fusion Science and Engineering 06 Oct. 2010 19 (34)
Results - JET
I (105 A)
B (T)
ne
(1019 m-3)
Wdia
(MJ)
Dα
(1016 s-1cm-2sr-1)
Input Power (107 W)
(δr=0.08%)
NBI Norm ~9.5MWNBI Tang ~6MWICRH ~1MW
Similarity of plasma paremeters, however Dα different
Ip ~ 2.4 MA
Bt ~ 2.4 T
ne ~ 7x1019 m-3
Wdia ~ 6 MJ
NBI Norm ~9.5MWNBI Tang ~6MWICRH ~1MW
t(s)
Time windows for CXSE
measurements (Δt=50ms)
and ELM frequency
Wdia ~ 5 MJ
ne ~ 6.8x1019 m-3
Bt ~ 2.4 T
Ip ~ 2.4 MA
(δr=0.75%)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 20 (34)
Results - JET
Toroidal velocity from edge CX was extracted from pedestal location
LCFS
― Ti (edge CX)
― Te (HRTS)
- - ne (HRTS)
T (keV)
4
3
2
1
0
vφ (km/s)LCFS
Pedestal location
3.5 3.6 3.7 3.8 3.9
R(m)
3.5 3.6 3.7 3.8 3.9
R(m)
200
150
100
50
0
Doctorate in Fusion Science and Engineering 06 Oct. 2010 21 (34)
Results - JET
Increase in δr leads to a degradation in the total pedestal pressure
Doctorate in Fusion Science and Engineering 06 Oct. 2010 22 (34)
Results - JET
pped presents lower values as the rotation decrease
Doctorate in Fusion Science and Engineering 06 Oct. 2010 23 (34)
Results - JET
pped decrease as the fELM increase
It seems that ripple is not directly influencing the ELM frequency.
Doctorate in Fusion Science and Engineering 06 Oct. 2010 24 (34)
Results - JET
Results indicate that absolute vφ is influencing the fELM
Velocity amplitude seems to be linked with felm, not ripple
Why?
Doctorate in Fusion Science and Engineering 06 Oct. 2010 25 (34)
Results - JET
Er and hence the ωExB is a key factor to reduce turbulent transport and stabilization of MHD activity.
Er can be written as:
▬77078 (δr=0.08%)
▬77084 (δr=0.75%)
▬77078 (δr=0.08%)
▬77084 (δr=0.75%)
Er
105 (V m-1)
ρ ρ
Well depth:
~ 60 kV/m 77078 (δr=0.08%)
~ 40 kV/m 77084 (δr=0.75%)
Higher well depth for low ripple
~60kV/m
~40kV/m
105 (V m-1)
▬77078 (δr=0.08%)
▬77084 (δr=0.75%)
JET Pulse # 77078 (δr=0.08%) # 77084 (δr=0.75%)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 26 (34)
Results - JET
[9] T.S. Hahm, Phys. Plasmas 2 p. 1648, 1995
ωExB is higher for low ripple
[9]
Futher work required: MHD Stability
▬77078 (δr=0.08%)
▬77084 (δr=0.75%)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 27 (34)
Results - JET
A working model for ELMs is that they are intermediate toroidal mode number, n~5-30,
peeling-ballooning modes.
[10] L.L.Lao et al. 29th EPS, 2002 [11] Snyder Nucl. Fusion 47, 961, 2007 [12] S Saarelma PPCF 49, 31, 2007
vφ at the edge? MHD stability MISHKA code simulations
ELMs event occur when the growth rates of the intermediate n MHD modes become sufficiently
large [10].
Peeling-ballooning modes are affected by:
- Edge pressure gradient and edge current density [11]
- But sheared toroidal rotation has been reported as having a stabilizing effect [12].
Doctorate in Fusion Science and Engineering 06 Oct. 2010 28 (34)
Results - JET
Summary and Perspectives:
Increase in δr leads to a degradation in the total pedestal pressure.
Seems that ripple is not directly influencing the ELM frequency.
Results show that it is |vφped| that influences the fELM. As |vφ
ped| decrease the fELM increase
Preliminar results show:- Er is dominated by the vφ term- well depth is higher for low ripple- ωExB corroborate the indication that turbulence is suppressed for low ripple
Future work:MHD stability is being investigated using MISHKA code simulations(Paper under is way for publication)
Doctorate in Fusion Science and Engineering 06 Oct. 2010 29 (34)
Results - Tore Supra
SOL flows are observed to be highly asymmetric and their flow direction depend on
magnetic configuration
Such flows are known to impose boundary conditions which can affect the core
plasma rotation
Report from Alcator CMod shown [13]:
flow momentum can couple across the separatrix inducing co- or counter-current
increment in central plasma rotation of the same sign of the flow in the SOL
Doctorate in Fusion Science and Engineering 06 Oct. 2010 30 (34)
Results - Tore Supra
Study the effect of SOL flows on confined plasma rotation:
- parallel SOL flows using a Mach probe (in SOL) [14]
- perpendicular ExB velocity using Doppler reflectometry
(over SOL, edge and core) [15]
- toroidal velocity using Charge eXchange Recombination
Spectroscopy (from edge to core) [16]
[14] J. Gunn et al. , Journal of Nuclear Materials 363, 484 (2007) [15] P. Hennequin et al. , Nuclear Fusion 46, S771 (2006)
[16] C. Gil, C. De Michelis, D. Elbeze, C. Fenzi et al., Fusion Science and Technology 56, 1219 (2009)
TS operated in ohmic circular plasmas
Contact point: LFS Top or LFS Bottom of the outboard limiter
Movable Mach probe
Doctorate in Fusion Science and Engineering 06 Oct. 2010 31 (34)
Results - Tore Supra
Parallel Mach number M// (=v///cs) [14]
[14] J. Gunn et al. , Journal of Nuclear Materials 363, 484 (2007)
[15] P. Hennequin et al. , Nuclear Fusion 46, S771 (2006)
Doppler reflectometry system [15]
Turbulence has k//~0, so k ~ k┴
Doppler shift ->v┴
v┴ ~ vphase + vExB ~ vExB
P. Hennequin et al., EPS 2010
“Effect of SOL flows modifications on edge and core radial electric field and rotation in Tore Supra”
Doctorate in Fusion Science and Engineering 06 Oct. 2010 32 (34)
Results - Tore Supra
[]
P. Hennequin et al., EPS 2010
“Effect of SOL flows modifications on edge and core radial electric field and rotation in Tore Supra”
Bottom: corresponds to co-current direction.
Top: the flow is reversed (counter-current) in the whole SOL
Effect on vφ Bottom: SOL parallel flow is co-current, which induces a co-current increment of the toroidal velocity at the edge
Top: far SOL parallel flow is reversed to counter-current direction, the toroidal velocity also becomes more counter-current
Doctorate in Fusion Science and Engineering 06 Oct. 2010 33 (34)
- JET / Tore Supra
- NBI
- Charge-eXchange Recombination Spectroscopy (CXRS)
- Results
- Future work and perspectives
Outline
Doctorate in Fusion Science and Engineering 06 Oct. 2010 34 (34)
JET:
Conclude the ongoing analysis
(Paper in preparation)
L-H/H-L transition effect on rotation
(or vice-versa)
Investigate L-H transition on EFCC
discharge
Future work and perspectives
Tore Supra:
Conclude the ongoing analysis
Investigate the influence of ne and Ip on
vφ