DEVELOPMENT OF LONG DURATION PLASMA ......DEVELOPMENT OF LONG DURATION PLASMA SCENARIOS FOR WEST | PAGE 1 R. Dumont | 8th IAEA TM on Steady State Operation of Magnetic Fusion Devices

DEVELOPMENT OF LONG DURATION PLASMA

SCENARIOS FOR WEST

| PAGE 1R. Dumont | 8th IAEA TM on Steady State

Operation of Magnetic Fusion Devices | May 26-29, 2015

R. Dumont, C. Bourdelle, J.-F. Artaud, L. Colas, L. Delpech, J. Decker,

A. Ekedahl, M. Goniche, W. Helou, J. Hillairet, G. Lombard, P. Mollard,

E. Nardon, Y. Peysson, E. Tsitrone and the Tore Supra / WEST TeamCEA, IRFM, F-13108 Saint-Paul-lez-Durance, France.

OUTLINE

• WEST in support of ITER

• Long-pulse plasma operation :from Tore Supra to WEST

• Preparing steady-state scenariosfor WEST

• Summary

R. Dumont | 8th IAEA TM on Steady State Operation of Magnetic Fusion Devices | May 26-29, 2015 | PAGE 2

WEST IN SUPPORT OF ITER : MAIN OBJECTIVES


• Pave the way towards the ITER actively cooled tungsten divertorprocurement and operation • Power handling capability / lifetime of

ITER tungsten divertor components in a tokamak environment(10 MW/m2 in steady-state)

WEST divertor

ITER divertor

[D. Van Houtte, Thursday, I-2]

• Master integrated plasma scenario over relevant plasma wall equilibrium time scale in a metallic environment

• Demonstration of integrated long pulse H mode scenario (optimization of RF heating, tungsten control and plasma density…)

• Investigation of advanced scenario regimes (fully non inductive H mode operation, highly radiating scenario, …)

| PAGE 4

R. Dumont | 8th IAEA TM on Steady State Operation of Magnetic Fusion Devices | May 26-29, 2015

WEST IN SUPPORT OF ITER

LONG-PULSE PLASMA OPERATION : FROM TORE SUPRA TO WEST

PREPARING STEADY-STATE SCENARIOSFOR WEST

SUMMARY

WEST IS BUILT ON THE TORE SUPRA FOUNDATIONS


• Long pulse operation pioneered for more than 20 years (first plasma 1988)

• World record of injected/extracted energy in a tokamak (1GJ)

• Several generations of carbon PFCs designed, manufactured and operated

Tore Supra designed for long pulse operation• Superconducting toroidal coils

• Cryogenic plant

• Pressurized water loops

• 15 MW of RF power for H&CD

• Fuelling systems

• Diagnostics

GIGAJOULE PLASMA OPERATION AT INCREASING RF POWER IN TORE SUPRA


Years

• Various operational / physics issues addressed :IR monitoring of PFC, CFC limiter state of surface / conditioning, RF wave coupling

with simultaneous heating systems, MHD stability, non-linear oscillations…

[Van Houtte NF 2004, Ekedahl NF 2010, Goniche PoP 2014, Dumont PPCF 2014]

COMPLEMENTARY RF SYSTEMS KEY TOLONG-PULSE OPERATION IN TORE SUPRA


• Lower Hybrid Current Drive(LHCD)• 7MW / 1000s

• 2 launchers (FAM and PAM)

• Main current drive source to operate at Vloop ~ 0

• Ion Cyclotron Resonance Heating (ICRH)• 9MW / 30s, 3MW / 1000s

• 3 double-strap antennas

• Central plasma heating

• MHD stability (fast ion stabilization + changes of equilibrium)

[Dumont PPCF 2014]

TORE SUPRA WEST : NEW PLASMA CONFIGURATION & W ENVIRONMENT


• Full tungsten environment (bulk & coated) [D. Van Houtte, Thursday, I-2]

• Various system upgrades, e.g. cryoplant [V. Lamaison, Wednesday, P-2]

Limiter configuration Divertor configuration

WEST

Divertor coil

Divertor coil

Stabilizing plate

Stabilizing plate

• X-point cross section:• Insertion of two poloidal field coils inside the existing vacuum vessel• Minor radius reduced (a ~ 0.5m); Plasma volume reduced (15m3)• Large aspect ratio: A ~ 5 (R ~ 2.5m; a ~ 0.5m)

HEATING & CURRENT DRIVE IN WEST IS EXCLUSIVELY PROVIDED BY RF SYSTEM


• LHCD system (6-7MW / 1000s) : non-inductive operation• Adaptation to WEST : modification of FAM launcher toroidal curvature

• Challenges : RF power coupling, efficient current drive at high density

• ICRF system (9MW / 30s, 3MW / 1000s) : central plasma heating• Adaptation to WEST : Three new ELM-resilient antennas under

fabrication in collaboration with ASIPP [J. Hillairet, Friday, O-10]

• Challenges : RF power coupling, operation in W environment

Expected L to H power threshold: ~1.5-5 MW depending on plasma parameters

| PAGE 10





SUMMARY

METIS SIMULATIONS OF WEST SCENARIOS


• Dynamic modelling using METIS code, 0D version of CRONOS [Artaud NF 2010]• Constraints on heat flux, maximum target temperature, H factor• Existing models for nsep, density peaking, W cooling rate, Wped…[Bourdelle NF 2015]• METIS simulations tuned and tested on JET-ILW and ASDEX Upgrade pulses

• Ongoing sensitivity studies, consistency checks against advanced modules

VARIETY OF EQUILIBRIUM / PROFILESWITH H=1 ARE CONSIDERED


Te (keV) ne (m-3) q

Scenario for METIS simulations (BT = 3.6T) High power Standard High fluenceIp (MA) 0.8 0.6 0.6ne (1019m-3) 8 7 6.7 fGW 64% 75% 72%Padd (MW) 15 12 10

ne,ped ~ 5×1019 m-3

ne,ped , Ttarget compatible with divertor and LHCD operation

[Bourdelle NF 2015]

FREQUENCY CHOICE FOR OPTIMAL H-MINORITYICRH SCENARIO


55.5MHz

RF power on H ions [kW/m3]

Optimizedfast ion confinement

54.0MHz

Maximum central heating, narrowest deposition

Two pre-set frequency bands at generator (55.5 ± 2MHz and 53.0 ± 2MHz)

EVE/AQL simulations: [Dumont NF 2013]

IMPACT OF ION / ELECTRON HEATING RATIO ON CORE W TRANSPORT STILL UNCLEAR


nH/ne=6%, PICRH = 6MW

Additional flexibility is desirable within D(H) heating scenario

• Higher ICRH power increases electron heating fraction

• Higher H-minority concentration favors ion heating

PICRH=6MW

nH/ne=6%

LHCD MODELLING FOR WEST DIFFERS FROM PAST TORE SUPRA RESULTS


Te (keV)

ne (m-3)

LUKE/C3PO simulations: [Decker PoP 2014]

• 6MW coupled by two launchers: FAM & PAM, n//0 = 2.0.

• Ray propagation limited by accessibility, then upshift due to X-point, large aspect ratio.

High power High fluence

THE TAIL LH MODEL PREDICTS CENTRAL LH POWER DAMPING WITH GOOD EFFICIENCY


• Tail LH model has successfully reproduced Tore

Supra and EAST discharges.

• 50% of LH power in main lobe to higher n//.[Decker PoP 2014, Peysson EPS 2015]

η = 1.23 1019 A/W/m2η = 1.46 1019 A/W/m2

• Central LH power damping; good CD efficiency

• Weak effect of radial transport (< 4m2/s).

High power High fluence

SEVERAL SCENARIOS COMPATIBLE WITH LONG PULSE OPERATION AT HIGH PEDESTAL DENSITY


Scenario (BT = 3.6T) METIS simulations, H98 = 1.0 High power Standard High fluence,

less LHCD

Ip (MA) 0.8 0.6 0.6ne (1019m-3) 8 7 6.7 fGW 64% 75% 72%LHCD (MW) 6 6 6.3ICRH (MW) 9 6 3Tped (keV) 0.6 0.4 0.3nped (1019m-3) 5.3 4.8 5.0Bootstrap fraction (%) 19 30 29LHCD fraction (%) 53 63 73LHCD eff. (1020A/W/m2) 0.14 0.11 0.12Loop voltage (mV) 78 23 6Pulse length (s): 14 Wb or ICRH generator limit 30s 60s 1000s

Long pulse operation achievable at ne,ped compatible with divertor operation

| PAGE 18





SUMMARY

SUMMARY


• WEST aims at testing ITER PFC in steady-state conditions (10MW/m2)• Built on the Tore Supra experience

• Circular → X-point plasma cross section, H mode

• New set of PFC adapted to steady-state operation

• First assembly phase completed – First plasma : mid-2016

• Heating and current drive exclusively provided by RF systems• ICRF in D(H) scenario with frequency range suited for central/HFS

deposition, additional flexibility by varying nH/ne

• LHCD predicted to be central, with efficiency 0.10-0.15x1020A/W/m2

• Long-pulse scenarios being prepared with integrated modelling tools• High power (30s), standard (60s), high fluence (1000s)

• Sustainment of ELMy H-mode with 10-20MW/m2 achievable

• All collaborations welcome. Call for participation : 2nd semester 2015

DSMIRFMSCCP

Commissariat à l’énergie atomique et aux énergies alternativesCentre de Cadarache | 13108 Saint Paul Lez Durance CedexT. +33 (0)4 42 25 46 59 | F. +33 (0)4 42 25 64 21

Etablissement public à caractère industriel et commercial | RCS Paris B 775 685 019

| PAGE 20


WEST RF CAPABILITIES SHOULD BE SUFFICIENTTO ENSURE ACCESS TO H-MODE REGIMES


[Bourdelle NF 2015]

Some remaining uncertainty related to aspect ratio, magnetic ripple level

X-POINT HEIGHT FLEXIBILITY TO ENSUREOPERATION AT 10-20MW/M2


Accessible Ip and X–point height depend on regime of operation(CEDRES++ equilibria, Bt=3.7T)

[Bourdelle NF 2015]

FLEXIBLITY ON HEAT FLUX ON DIVERTOR TARGETSFROM X-POINT HEIGHT, ADDITIONAL POWER


[Bourdelle NF 2015]

PREDICTION OF TARGET TEMPERATURE VERSUS DENSITY AT SEPARATRIX


[Bourdelle NF 2015]

Documents

DEVELOPMENT OF LONG DURATION PLASMA ......DEVELOPMENT OF LONG DURATION PLASMA SCENARIOS FOR WEST | PAGE 1 R. Dumont | 8th IAEA TM on Steady State Operation of Magnetic Fusion Devices