RF2011, Newport, RI 1 June 2011 1 Long Pulse Operation with the ITER-Relevant LHCD Antenna in Tore Supra A Ekedahl 1, L Delpech 1, M Goniche 1, D Guilhem

RF2011, Newport, RI 1 June 2011 1

Long Pulse Operation Long Pulse Operation with the ITER-Relevant with the ITER-Relevant

LHCD Antenna in Tore Supra LHCD Antenna in Tore Supra

A EkedahlA Ekedahl11, L Delpech, L Delpech11, M Goniche, M Goniche11, D Guilhem, D Guilhem11, J Hillairet, J Hillairet11, M Preynas, M Preynas11, PK Sharma, PK Sharma22, J , J AchardAchard11, YS Bae, YS Bae33, X Bai, X Bai44, C Balorin, C Balorin11, Y Baranov, Y Baranov55, V Basiuk, V Basiuk11, A Bécoulet, A Bécoulet11, J Belo, J Belo66, ,

G Berger-ByG Berger-By11, S Brémond, S Brémond11, C Castaldo, C Castaldo77, S Ceccuzzi, S Ceccuzzi77, R Cesario, R Cesario77, E Corbel, E Corbel11, , X CourtoisX Courtois11, J Decker, J Decker11, E Delmas, E Delmas88, BJ Ding, BJ Ding99, X Ding, X Ding44, D Douai, D Douai11, R Dumont, R Dumont11, C Goletto, C Goletto11, ,

JP GunnJP Gunn11, P Hertout, P Hertout11, GT Hoang, GT Hoang11, F Imbeaux, F Imbeaux11, KK Kirov, KK Kirov55, X Litaudon, X Litaudon11, P Lotte, P Lotte11, , R MagneR Magne11, J Mailloux, J Mailloux55, D Mazon, D Mazon11, F Mirizzi, F Mirizzi77, P Mollard, P Mollard11, P Moreau, P Moreau11, T Oosako, T Oosako11, ,

V PetrzilkaV Petrzilka1010, Y Peysson, Y Peysson11,, S Poli S Poli11, M Prou, M Prou11, F Saint-Laurent, F Saint-Laurent11, F Samaille, F Samaille11, B Saoutic, B Saoutic11

1) CEA, IRFM, 13108 Saint Paul-lez-Durance, France.2) Permanent address: Institute for Plasma Research, Bhat, Gandhinagar, Gujarat, India.

3) National Fusion Research Institute, Daejeon, South Korea.4) Southwestern Institute of Physics, Chengdu, P R China.

5) Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK.6) Associaçao Euratom-IST, Centro de Fusao Nuclear 1049-001 Lisboa, Portugal.

7) Associazione Euratom-ENEA sulla Fusione, CR Frascati, Roma, Italy.8) Present address: ITER Organization, 13067 Saint Paul-lez-Durance, France.

9) Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, P R China.10) Association Euratom-IPP.CR, Za Slovankou 3, 182 21 Praha 8, Czech Republic.

A. Ekedahl et al RF2011, Newport, RI 1 June 2011 2

Outline

• Introduction and motivation

> LHCD system upgrade in Tore Supra > Lower Hybrid Current Drive (LHCD) for ITER> Manufacturing and installation of the new LHCD antenna

• Experimental results

> First commissioning period (Sept 2009 – March 2010)> Long pulse operation with full LHCD system (from Oct 2010)

• Summary

A. Ekedahl et al RF2011, Newport, RI 1 June 2011

New LHCD system for CW operation

~ 7 tons! ¼ ITER antenna

700kW/klystron CW

Together with the upgrade of the LHCD generator, the new antenna is a key element of the LHCD system upgrade in Tore Supra

Increased LHCD capability to ~10MW / 1000s (3.7GHz) at the generator

Extended domain of long pulse operation for Tore Supra: higher density and plasma current

Passive Active Multijunction (PAM) chosen for Tore Supra, since preferred option for ITER

PAM

3


Which mission(s) for LHCD in ITER ?

Save Volt-seconds from early plasma phase (up to 58Wb) Extend burn duration (extend burn phase to ~500s)

Help accessing and sustaining steady-state scenario Drive far off-axis current, complementarily to bootstrap

current, NBCD and ECCD.

Challenges for ITER:• Technology for long pulses• Coupling of RF waves in ITER

GT Hoang et al., Nucl. Fusion (2009)

4

Modelling of ITER LHCD antenna: J Hillairet et al., Poster B-08 Thursday


Passive Active Multijunction (PAM)

Passive Active Multijunction (PAM):

Alternance of active waveguides and passive waveguides

• Allows cooling channels close to the plasma (heat load, ITER environment)

• Low reflected power at cut-off density (far distance coupling required in ITER)

PAM Concept: Ph Bibet et al., Nucl. Fusion (1995)

Tore Supra (TS) LHCD PAM antenna

TS PAM design: J Belo, Ph Bibet et al., FED (2005)


Manufacturing of the PAM blocks

Assembly of the 17 plates with brazing material to constitute one of the two PAM blocks. The two PAM blocks are then joined together by electron beam welding.

Brazing material (Cu-Sil) 40 µm

7 days in oven (850C).Use of pressurized bellows Patented by CEA

D Guilhem et al., FED (2011)

6

0.6m


Installation of the Tore Supra PAM antenna

Insertion in Tore Supra, August 2009

7 tons, millimeter precision!

E Delmas et al.,

7


1) At low power, characterise the reflection coefficient behaviour. Validate the ALOHA coupling code.

2) Assess coupling during edge perturbations, mimicking ELM behaviour.

3) Achieve ITER-relevant power density, i.e. 25MW/m2 at f = 3.7GHz (equivalent to 33MW/m2 at f = 5GHz).

4) Full non-inductive discharges (VLoop = 0) with PAM.

Goals of the PAM commissioning in Tore Supra

First test of a PAM carried out FTU, 8GHz, short pulses (<1s): V Pericoli et al., Nucl. Fusion (2005)

Participation of 15 collaborators from 7 countries:IST Lisbon; IPP-CR Prague; CCFE Culham; ENEA Frascati; IPR India; SWIP China; ASIPP China; NFRI South Korea;

ALOHA code: J Hillairet et al., Nucl. Fusion (2010)

Fast and smooth commissioning period of PAM


Low reflected power level with PAM

Lower reflected power compared to Full Active Multijunction (FAM) at larger plasma-launcher gap: follows design specification & linear theory

PAM

FAM (1st gen.) FAM (2nd gen.)

FAM

FAM

First generation(No longer in use on TS)

Second generation (3.5MW coupled power so far)

PAM


Coupling agrees with linear theory

Computed RC with ALOHA vs density, for different gradients

Low reflection coefficient (RC< 2%) near cut-off density

Low power (~200kW) for comparison to linear theory

M Preynas et al., Nucl. Fusion (2011),Poster B-06 Thursday

ALOHA

ne (1017m-3)

A

vera

ge

RC

(%

)

nco = 1.7*1017m-3 at f = 3.7GHz


Coupling during edge pertubations demonstrated

Supersonic Molecular Beam Injection (SMBI) to mimic ELMs

• Reflection coefficient behaves according to modelling. • At least intermediate power (1.5MW) can be maintained during SMBI.

LH power deposition shape does not change during edge perturbations

PK Sharma et al., 37th EPS (2010)

11

Hard X Ray profile, 60-80 keV


ITER-relevant power density for 78s

• 2.75MW (25MW/m2) coupled with PAM for 78 seconds• Low RC (< 2%) at large plasma-launcher gap (> 10cm) • Efficient cooling: Waveguides and side protections below 270C

ELHCD = 220MJ

IR surveillance

A Ekedahl et al., Nucl. Fusion (2010)


Full CD regime (PAM alone) for 50s

Double feedback loops to maintain IP constant and VLoop=0

CD efficiency with PAM: LHCD ~ 0.75x1019A/W/m2

Similar to Full Active Multijunction antennas (GJ-discharges)

Hard X Ray profile, 60-80 keV

0.51MA, BT = 2.7T)

13

HXR profile (LH deposition profile) peaked at r/a ~ 0.25

A Ekedahl et al., Nucl. Fusion (2010)


n// spectrum from ALOHA code (using measured values of power, phase and edge density)

Ray-tracing modelling of full current drive discharge

n// spectrum (ALOHA)

Ray tracing code, C3PO, using 36 rays (6 n//-values x 6 waveguide rows)

Y Peysson and J Decker. Report EUR-CEA-FC-1739, Euratom-CEA (2008)


Good agreement with modelling, in this example

C3PO/LUKE reproduce well the HXR profile and the driven current.

Synthetic diagnostic models well the line integrated HXR emission. Y Peysson and J Decker, PoP (2008)J Decker et al., Poster A-50 Wednesday

Although good agreement in this example, robustness in LHCD modelling is still required. Y Peysson et al., Poster A-29 Wednesday

IPlasma exp: 510kAILH LUKE: 508kAILH Cronos/HXR: 443kA

ExperimentModelling

Line integrated HXR emissionLH current profile for #45534

Dfast = 0.1m2/s


M Goniche et al., PPCF (2010), Poster A-27 Wednesday

LHCD at high density: effect of fuelling method

HXR emission decays as ne-3, and

even faster above <ne> ~ 4*1019m-3.

Faster decay of HXR-signal is correlated with increase in density fluctuation rate at the antenna.

T Oosako et al., Poster A-28 Wednesday

ITPA task on LHCD efficiency at high density

Gas

Pellets

PelletsGas

ISat level and fluctuation rateHXR emission (60-80 keV)


Summary of PAM commissioning

Number of sessions Number of pulses

2009 14 (+ 2 parasitic) 240

2010 17 274

Total 31 (+ 2 parasitic) 514

Fast and smooth commissioning period2.7MW coupled after 240 pulses on plasmaAfter 500 pulses: 9.7GJ accumulated injected energyLarge fraction of time operated at high power (> 2MW)

Accumulated time at given power All in good shape after the campaign

17

25MW/m2


First half of LHCD plant equipped with CW klystrons

High power CW klystrons: L Delpech et al., Poster A-26 Wednesday

RF control system: G Berger-By et al., Poster A-25 Wednesday

Pulses with up to 3MW/43s achieved with Full Active Multi-junction antenna, fed by a set of eight 700 kW/CW klystrons

TH2013C: 700kW CW on matched load

18

#46518

PLH = 3MW


Long pulse operation with both LHCD antennas

Both LHCD antennas together 4.5MW/150s obtained (650MJ injected energy)

Opens new operational space (ne, IP) for long pulse operation

Slight increase in density due to non-optimised feedback control

PAM, FAM

Total PLHCD


Summary

ITER-relevant LHCD antenna (PAM) now in routine operation in Tore Supra.

Very encouraging results for non-inductive current drive in long pulse operation on Tore Supra:

• Fast commissioning of PAM: 2.7MW reached after 240 pulses on plasma.

• Far distance coupling: RC ~ 2% at large gap (10cm)• Good agreement with ALOHA coupling code• Long pulse capability at ITER-relevant power density:

so far 25MW/m2 / 78s.• CD capability similar to Full Active MultijunctionGives good confidence for ITER LHCD design

Next: Full CW LHCD system with eight new generation klystrons on PAM antenna.


Posters, Wednesday 1/6:

A-25: G Berger-By Tore Supra LH transmitter upgrade, RF driver for the power

spectrum

A-26: L Delpech Validation on plasma of the Tore Supra CW LHCD generator

A-27: M Goniche LHCD Experiments at high density on Tore Supra

A-28: T Oosako SOL density fluctuations in front of the Tore Supra PAM launcher

A-29: Y Peysson Effect of plasma fluctuations on lower hybrid current drive

A-50: J Decker Bremsstrahlung emission modelling and fast electron physics

A-52: D Douai Modelling of Ion Cyclotron Wall Conditioning plasmas

Posters, Thursday 2/6:

B-06: M Preynas Coupling of the ITER-relevant LH antenna in Tore Supra

B-08: J Hillairet RF modeling of the Lower Hybrid Antenna proposed for ITER

B-19: J-M Bernard TITAN: a test-bed facility for ICRH antenna and components of

ITER

B-33: J Jacquot Self-consistent non-linear RF wave propagation

B-34: M Kubic Attenuation of ICRH-induced potentials in the SOL of Tore Supra

IRFM / Tore Supra contributions at this conference

Documents

RF2011, Newport, RI 1 June 2011 1 Long Pulse Operation with the ITER-Relevant LHCD Antenna in Tore Supra A Ekedahl 1, L Delpech 1, M Goniche 1, D Guilhem