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

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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

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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

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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

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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%)

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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

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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%)

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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”

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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