Y. Kamada

JAEA

TCM-8 meeting, 2010, April 14 ENEA Frascati, Italy

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JT-60SA Plasma Regimes and Research Plan

The JT-60SA Project The JT-60SA project is conducted under the BA Satellite Tokamak Programme by Europe and Japan, and the Japanese National Programme.

JT-60SA and ITER should be operated as a ‘set’, in order to realize the Fusion Energy for both * science and technology * scientists

The project mission is to contribute to early realization of fusion energy by supporting exploitation of ITER and by complementing ITER with resolving key physics and engineering issues for DEMO reactors.

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JT-60SA Plasma Regimes

JT-60SA is a fully superconducting tokamak capable of confining break-even equivalent class high-temperature deuterium plasmas (Ip-max=5.5 MA) lasting for a duration (typically 100s) longer than the timescales characterizing the key plasma processes, such as current diffusion and particle recycling.

JT-60SA should pursue full non-inductive steady-state operations with high N (> no-wall ideal MHD stability limits).

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Sustainment Time (s)

0

1

5

6

4

3

2

0 3000400

JT-60SA Target

10020 40 60 80

DEMO reactors

ITER

ITER

NExisting Tokamaks

JT-60U Steady-state

Inductive

EU & JA Share ProcurementsEU & JA Share Procurements

Design of the key components has been almost completed.The JT-60SA project has been entered its manufacturing stage.

Laser scattering Cryostat

TF coils&Testing

Assembly

NBI

In-vessel Components

Remote Handling

Vacuum Vessel

Diagnostics

CS, EF coils

Disassembly

Rad. safety

Cont/data

Magnet Interface

Power Supplies

Cryogenic System

ECRF

Compressor Building

Water Cooling System

Naka site

16m

Base: 260t

Body: 350t

150t

700t

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Project Schedule

JT-60SA: Highly Shaped Large Superconducting Tokamak

• A wide range of plasma equilibrium covering a high plasma shaping factor of S=q95Ip/(aBt) ~7 and a low aspect ratio of A~2.5 with a sufficient inductive plasma current flattop and additional heating up to 41 MW during 100 s.

The plasma size is ~ 0.5 x ITER = between ITER and other superconducting tokamaks. An integrated knowledge of superconducting tokamaks SST-1, EAST, KSTAR, TORE-SUPRA, JT-60SA and ITER will establish a reliable nuclear fusion science and technology towards DEMO. 6

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Typical Plasma Parameters

Ip=5.5MA, Double Null

Ip=4.6MA ITER-shape

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Ip=5.5MA Discharge Example

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High N , high bootstrap Steady-state operation

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High N steady-state operation space

Research needs for ITER & DEMO

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 Fully Superconducting Large Tokamak Highly Shaped Plasma Configuration  Strong Heating and Current Drive Power with Variety & Long Pulse

Large Capability of Stability Control  Large Capability of Divertor Power Handling and Particle Control Variety of High Resolution Diagnostics

JT-60SA device has been designed in order to satisfy the central research needs for ITER and DEMO

JT-60SA device

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41MWx100s High Power Heating with Variety

Positive-ion-source NB85keV12units x 2MW=24MWCOx2u, 4MWCTRx2u, 4MWPerpx8u, 16MW

Negative-ion-source NB500keV, 10MWOff-axis for NBCD

variety of heating/current-drive/ momentum-input combinations

ECRF: 110GHz, 7MW x 100s 9 Gyrotrons, 4 Launchers with movable mirror >5kHz modulation

NB: 34MWx100s

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ECRFNB

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In-vessel components for stability control

RFX

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Divertor Structure for heat & particle control

Research phases and status of key components

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JT-60SA operation starts earlier than ITER’s hydrogen operation by ~5 years. The tight schedule of ITER up to DT1 requires sufficient explorations of the key physics and operational techniques in satellite devices. => Experiences and achievements in JT-60SA are indispensable for smooth and reliable progress of ITER.

Divertor & Wall Material Research for DEMO

Extended Research Phase:Installation of the metallic divertor targets and first wall together with an advanced shape divertor will be conducted based on progress of the research in the world tokamaks including ITER. 

Integrated Research Phase:The material of the divertor target and the first wall is now considered to be carbon before achievement of the JT-60SA’s main mission of the high- steady-state. However, possibility of replacement to metallic materials will be discussed based on the results in JET, ASDEX-U, FTU.

Replaceable Divertor Cassette

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JT-60SA Research Plan

ITER & DEMO-relevant non-dimensional regime

JT-60SA allows explorations in the ITER- and DEMO-relevant plasma regimes in terms of non-dimensional plasma parameters at high plasma densities in the range of 1×1020/m3.

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ITER & DEMO-relevant heating condition / scan

ECH (110GHz, 7MW) N-NB (500keV, 10MW) => Electron Heating dominant Low Particle input Low Torque input

P-NB (85keV, 24 MW) => Ion Heating dominant

Perp-NB & balanced CO/CTR-NB => low torque input ( torque input scan)

JT-60SA allows dominant electron heating, scan of power ratio to electron high power heating with low central fueling high power heating with low external torque input ( incl. scan of rotation)

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Study on highly self-regulating plasmas for DEMO

High beta & high bootstrap fraction => strong linkages among j(r), p(r), Vt(r)+ Global linkage / Global structure including core & pedestal+ Linkage among transport coefficients & roles of MHD activities=> JT-60SA allows understanding & control of this plasma system at ITER- & DEMO-relevant non-dimensional parameters (*,*, N, p, q95…)

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JT-60SA plasma actuator system allows separated controls for heating, current drive, rotation drive & fueling.

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RWM control coils

Stabilizing plate

JT-60SA allows exploitations of high beta regimes with the high shape factor S up to 7, the stabilizing shell, the RWM control coils, the error field correction coils, and the high power heating & CD & momentum-input.

Demonstration & Study of High Beta (>non-wall limit) for DEMO

For DEMO, minimum rotation for RWM stabilization has to be studied => w/o control coils.Identification of the disruption limits at high N.

Ncritical = 4.32

Nno-wall = 3.12 N

ideal-wall =4.40

JT-60SA supports ITER’s main mission & commissioning with high Ip, high power, high density plasmas

* H-mode operations towards Q=10 L-H transition Pedestal Structure H-mode confinement ( incl. compatibility with radiative divertor, RMP, etc.)•Disruption behavior, and disruption prediction & mitigation using the same techniques planed in ITER.

•Operation scenario optimization with superconducting PF coils.

•Divertor heat load mitigation ( incl. ELMs) and particle controllability

JT-60SA has sufficient power for L-H transition & H-mode confinement studies at Ip=5.5MA & ne=1020m-3.

JT-60SA provides data & techniques for

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0102030400.50.60.70.80.911.11.21.3P-LH1.5*P-LH2*P-LHLine Average Electron Density (1020m-3) Scenario 3: Ip=5.5MA, Bt=2.25T 0.4 x nGW nGW total injection power for Extended Reseach Phasetotal injection power for Initial Reseach Phase (II)

•with 10MW high energy (500keV) N-NB; NB Current Drive studies (incl. off-axis NBCD), AE mode stability & effects on fast-ion transport, Interactions between high energy ions and MHD instabilities

0

0.05

0.1

0.15

0.2

0.25

0

0.05

0.1

0.15

0.2

0.25

0.01 0.1 1 100.01 0.1 1 10

DIII-DJETASDEX-Usmall(co)small(bal)small(ctr)middle(co)middle(bal)middle(ctr)large(co)large(bal)large(ctr)

DIII-DJETASDEX-Usmall(co)small(bal)small(ctr)middle(co)middle(bal)middle(ctr)large(co)large(bal)large(ctr)

with FSTs[small(co)]with FSTs[large(co)]

with FSTs[small(co)]with FSTs[large(co)]

WE

LM

/ W

ped

e

5.5MA (DN, LN) ITER

4.6MA (ITER-like)

2.3MA (SS)

ELM mitigation for ITER and DEMO

JT-60SA’s high Ip high power H-mode plasmas allow type I ELM studies at sufficiently low edge collisionality.

JT-60SA

ELM

ene

rgy

loss

frac

tion

Error field correction / generation coils are used for RMP

2) JT-60SA’s high triangularity plasmas allow small ELM regimes ( i.e. grassy ELM) for DEMO. (DEMO-equivalent shape )=> ELM mitigation without RMP.

1) ELM mitigation by RMP & pellet inj. for ITER.

collisionality 25

JT-60SA

JT-60SA allows exploitations of NB Current Drive studies (incl. off-axis NBCD), AE mode stability & effects on fast-ion transport, Interactions between high energy ions and MHD instabilities with 10MW high energy (500keV) N-NB.

High Energy Particle Studies for ITER & DEMO

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• The peak heat flux can be suppressed within the mono block capability (15 MW/m2) by gas puffing for 41 MW injection. (ne,ave~1x1020 m-3 at fGW=0.8).

Divertor Power Handling for ITER & DEMO

Radiation map

== SONIC code simulation ==

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-0.05 0 0.05 0.1 0.15 0.2 0.25Distance from the separatrix [m]

10.4 MW/m2

Heat flux density on the LFS target

The ITER-like W-shaped divertor with a V-corner enhances divertor radiation.

CFC monoblock divertor target allows 15MW/m2.

Test at JEBIS at 15MW/m2 for 12 full-size mock-ups of monoblock target with 10 CFC blacks.

About half of mock-ups satisfied the requirements

• At lower ne compatible with lower Ip plasmas, qpeak = 8.6 MW/m2 is obtained with impurity seeding.

(30x30x30mm)

Qualified targets survived 2000 heat cycles

Divertor condition can be controlled from attached to detached conditions with constant main plasma density.

Divertor pumping with cryopumps allowsPumping speed of 0 -100m3/s by 8 steps.

Fuel & Impurity Particle Control for ITER & DEMO

Compatibility of the radiative divertor with impurity seeding and sufficiently high fuel purity in the core plasma should be demonstrated.

The key point is to clarify whether a wide range of the divertor plasma controllability can be realized independently of the main plasma operation condition.

JT-60SA demonstrates particle controls under saturated wall condition by utilizing variety of the fuelling and pumping systems (gas-puffing from man and divertor, pellet injection, divrtor pumping).

0246810020406080100120Pumping Speed (m 3/s)Divertor Electron Temperature (eV)Divertor Electron Density (1020m-3)05101520Divertor PeakHeat Load (MW/m2)Detached Divertor Attached Divertor monoblock CFC limit

High Integrated Performance for DEMO

‘Simultaneous & steady-state sustainment of the key performances required for DEMO’has never been achieved => the goal of JT-60SA.

Example of JT-60SAat Ip=2.3MA.

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Integrated Control Scenario Development Understanding & Control of the highly self-regulating

combined plasma system for DEMOHigh-beta, high-bootstrap fraction plasma => a highly self regulating non-linear system governed by strong linkages among j(r), p(r) and Vt(r) in core & pedestal.Strong spatial linkage : Core – Pedestal – SOL – Divertor plasmas

Study controllability & Plasma response

Determine the minimum suitable set of actuators & logic. +control marginagainst operation boundaries

(In particular disruption limits )

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main plasmaSOL/ divertorexternal heatingexternalpedestal plasmarecyclingneutralimpuritieionsParticle Control Current ProfileGlobal LinkageFlow Drive intrinsicPressureprofileFlow & Electric Field profile

Summary

The project mission of JT-60SA is to contribute to early realization of fusion energy by supporting exploitation of ITER and by complementing ITER for DEMO.

JT-60SA device has been designed in order to satisfy all of the central research needs for ITER and DEMO,

in particular, ‘Simultaneous & steady-state sustainment of the key performances required for DEMO’ & ‘Integrated Control Scenario Development ‘.

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JT-60SA is indispensable for ITER & DEMO JT-60SA operation starts earlier than ITER’s hydrogen operation by ~5 years. The tight schedule of ITER up to DT1 requires sufficient explorations of the key physics and operational techniques in satellite devices. => Experiences and achievements in JT-60SA are indispensable for smooth and reliable progress of ITER. For DEMO, an integration of achievements in JT-60SA high- steady-state plasmas and ITER burning plasmas is required to make DEMO designs more realistic and attractive. For early realization of DEMO, such integrated exploitation of JT-60SA and ITER is necessary.

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