- The ITER project - thermonuclear fusion for energy · tokamak regime at low plasma current (9MA...

1 University of Pavia, Italy, 4th March 2011

- The ITER project - thermonuclear fusion for energy!

Y. Peysson!

CEA/IRFM, France!

Email: yves.peysson@cea.fr! Thanks to J. M. Ané, J.F. Artaud, J. Decker!

Outline!

§  Energy and environmental issues!

§  Thermonuclear fusion basics!

§  From the tokamak concept to ITER!!§  ITER and the international fusion program!

§  Physics and integrated modeling!

- Energy and environmental issues -!

Prehistory! Middle age! Yesterday! (1975)!

! Tomorrow! (2020)!

24 TW!

Reference: 16 TW (2008) !

Industrial!revolution!

0.5 TW!… TW!

… TW!

e) “South”

“North”

6 billion inhabitants

8 to12 billion inhabitants

The challenge of the 21st century ?

Is fusion, too late ?

Fossile energies ! Reserve (10+22 J)! Ressources (year)!

Oil/Gas! 3.5! ≤ 70!Coal! 20! ≤ 400!

Fission (PWR)! 10 (250)! ≤ 200 (5.000)!

Fast Breeder! 200 (5.000)! ≤ 4.000 (100.000)!

Fusion D-T (*)! 60 (1.000.000)! ≤ 1.200 (20.000.000)!

Fusion D-D! (1.500.000.000)! (30.000.000.000)!

Renewable Energies! Power (TW)!

Hydroelectricity! 2.8!Wind mills! 2.8!

Geothermy! 1.8!

Sea heat! 0.9!

Tide/Waves! 0.04!

Averaged energy consumption ≈ 16 TW!

Ground (sea) !

Total solar power!170.000 TW!Solar power flux (equator)!0.3 kW/m2!Usable solar power flux ground!0.1 kW/m2!Photovoltaic conversion rate!max 10%!Conversion rate by photosynthesis

(biomass)!1%!!!!Installations of very large surface !(1.600.000 km2 = 4xFrance !)!Minimum duration to refund !the energy for manufacturing!photovoltaic cells!35 years!

Solar energy!

(*) Lithium !

Use of very large structures.!

Power density per unit of mass!

Renewable energy!

Nuclear energy!

Fossile energy!

Carbon dioxide emissions: CO2 !

The CO2 emission results mainly from the manufacturing of structural materials !!

Zoom on renewable energies, fission and fusion!

Coal Gas Solar Hydraulic Biomass Wind Fission Fusion!

Tons of CO2 per GWh Tons of CO2 per GWh! Tons of CO2 per GWh Tons of CO2 per GWh!

Distribution of energy consumption !

Transformation!

Solar! Others!Inhabitation! Transportation!

The recourse to the fusion energy seems not highly critical for short term energy needs taking into account of green house effect issues: the fission energy makes it possible to ensure the energy transition BUT waste and proliferation are unsolved problems at a large scale use. Fusion is therefore the unique alternative !

Electricity ? ! Hydrogen ?!

- Thermonuclear fusion basics -!

Francis Aston: nuclear binding energy!

Arthur Eddington: thermonuclear fusion is the energy of the stars!

Anton Gamow: first attempts of fusion experiments in labs!

Edward Teller: « father » of the H bomb on a suggestion of Enrico Fermi!

1940-1950!

1946-1958: time of the pioneers seeking the good magnetic configuration (~ bottle)!1958-1968: time of the international cooperation in spite of the cold war. Key role played by Lev Artsimovitch.!1968: era of the “Tokamaks” opened by russians physicits of the Kurchatov institute !!

Tokamak T1 (1960)!

toroïdalnaïa kamera s magnitnymi katushkami

Nuclear energy!

Fission!

Fusion!

Stability ↑!

Aston diagram!

The fusion energy is 4 times more effective than fission energy with equal fuel mass !!

Nuclear reaction of fusion of reference

T+!D+! He++ (3.6 MeV)!

n (14 MeV)!

Other types of reactions :

P + P 2,2 10-50! " ! ! ! ! ! D + e+ + V + 0,164 MeV

D + T 1,6 10-24! " ! ! ! ! ! 4He + n + 17,59 MeV (voir Figure 1a)

D + D1,1 10-26

! " ! ! ! ! !

1,2 10-26! " ! ! ! ! !

3He + nT + P

+ 3,27 MeV+ 4,03 MeV

! " ! ! ! ! ! 4He + 2n + 11,33 MeV3He + D ! " ! ! ! ! ! 4He + P + 18,35 MeV

7Li + n ! 4He + T + n - 2,5 MeV (93 % of natural lithium) ou : 6Li + n ! 4He + T + 4,8 MeV (7 % of natural lithium)

Tritium cycle :

No chain reaction and no radioactive waste (fuel) but activation possible (n)!

20 keV ~ 200.000.000° K!

  “The D-T mixture must be maintained at a temperature of 200 million degrees to improve the p robab i l i t y o f fus ion reactions between two nuclei. The charged particles must have enough kinetic energy to counterbalance the Coulomb repulsion.”!

Probability of fusion reaction

1 electron-Volt (eV) ~ 10.000° K!

The plasma: the 4th state of the matter

Positive power balance : Lawson criterion (1955) • Pfus = Pneut + Pα

• Pinj + Pα - Ploss = 0 et Ploss= W/τE

• Q= Pfus / Pinj

Break-even Q = 1 Pfus ≈ Pinj

Ignition Q = ∞ Pα ≈ Ploss

Pinj = 0

n T τE > 3×10+21 (keV. m-3.s)!

Pression !

Energy confinement!

Temperature!Density!

Magnetic fusion : low plasma pressure(~ 2 atm.), long confinement time (τE ~ 4s). High magnetic pressure by external windings (10 T ~ 400 atm.) → TORE SUPRA, JET,… ITER!

Inertial fusion : extreme plasma pressure (~ 3 billions atm., density ≥ 1000 solid density), short confinement time (residence of ions in the configuration, a ~ 0.1 mm, τE ~ 0.3 ns ). Confinement ensured by dynamic compression (laser lighting)→ LMJ!

Cold fusion: muons (mm = 207×me). Muonic hydrogen molecule is more compact, nucleus distance is 7 × 10-13 m (instead of 1.5 × 10-10 m). But only 150 reactions of fusion are catalysed by one muon before it disintegrates or before it is captured by a 4He. Balance energy reached beyond 1000 reactions only… !

n ~ 10+20 m-3 << nair ~ 3 ×10+25

m-3 !Almost vacuum ! !

Fusion beats Mooreʼs law!

Break-even!Ignition!

The key question: immaterial confinement

Mean free path between two collisions!

vth/ν ~ 10-30 km !!

@ 200 millions K!

Toric magnetic bottle!

Closed magnetic tracks!

Rectilinear magnetic bottle!

Open magnetic tracks+ stopper at the ends ! (magnetic mirror)!

Charged particle trajectory in a magnetic field!

Without magnetic field!

With magnetic field!

Cyclotronic motion and guiding-center!

- From the tokamak concept to ITER -!

Magnetic equilibrium jxB = ∇p!

!Compensate vertical drift by alternate up/down position!

Convective to diffusive process!

Ip - Ini

Circuit primaire Plasma

From pulsed operation to steady-state regime!

TOKAMAK = transformer!Plasma = secondary circuit!

Basic operation: inductive pulsed mode!

Non-inductive source of current!

!Additional heating power: Rp ~ Te

-3/2 !Primary cicuit!

Tokamak confinement time scaling law!

!Performances scale roughly like plasma current Ip, P-1/2, R3/2!

Gigantism of the machines for reaching ignition!

!TORE SUPRA!

JET!ITER!

The tokamak: advantages & disadvantages!+ Best achieved performances in terms of energy confinement!!-  Strong magnetic field (40000-120000 Gauss !): very large cost of the toroidal field coils (commercial competitiveness with this concept)!

-  Intrinsic complexity with helical magnetic field lines: plasma must enter into a highly non-linear self-consistent regime of stability: difficulty for an accurate feedback control of the plasma plasma by external means (performance/stability), in particular in the flat top regime (long current resistive diffusion time)!!- Pulsed regime (transformer): continuous operation requires to design additional heating and current drive systems (rf waves, neutral beams): efficiency and recycled fusion power!!-  Enormous amount of magnetic energy stored in the plasma: risk of severe degradation in the event of brutal loss of confinement (disruption). !!

Two main axes of research !

Duration!

La performance !

JET (JT-60U)

Iplasma B

Performances!TORE SUPRA

ITER-FEAT Ip ≤ 2.1 MA!Bt ≤ 3.9 T!ap ≤ 0.8 m!Rp ≈ 2.4 m!

Ip ≤ 7.0 MA!Bt ≤ 3.8 T!ap ≤ 1.3 m!Rp ≈ 3.1m!

ε ≤ 1.6!δ ≤ 0.5!

!Superconductors in superfluid helium at 1.8K!!Copper technology!

Current diffusion

Erosion

Millisecond Second Minute Hour

MHD Transport Plasma/wall Equilibrium

TFR! JET! TORE SUPRA! ITER !

Time scales and physical processes!

Fusion power on the JET tokamak!

• 16 MW of fusion power, limited by MHD. Close to break-even : Pα ~ Ploss

• 4 MW in stationnary regime (H mode) which is the reference opertaion for ITER-FEAT.

• The heating and the confinement of the α particles are not affected by instabilities (so far…)

ITER: Q=5-10 plasma dominated by α-particle heating !!

Tore Supra 25 m3

~ 0 MW Self-heating:0%

JET 80 m3

~16 MWth

ITER 830 m3

~ 500 MWth 70%

DEMO reactor ~ 1500 - 2000 m3

~ 4 500 MWth 80 - 90%

Plasma cores better and better insulated…

TORE SUPRA : CIEL configuration!

CIEL allows to extract continuously 15 MW of convected power and 10 MW radiated power!

!CIEL give access to the

physics and the technology of the long discharges: ~ 1000 seconds.!

8 to 12 MW / m2!

Pomped toroidal limiter!

First wall!

Plasma duration (s)!Plasma duration (minutes)!

ITER: long pulse operation (400s) but true steady-state regime ?!

•  Resistive time scale !

•  Fondamental eigenmode time scale! with λ1 ≈ 3.83.!!•  For ITER (Te0 = 15 keV, a = 2 m), τR

* ≈ 716 s !!

•  Very bad current drive efficiency because of the large size of the machine (R-1) besides the high plasma density: advanced tokamak regime at low plasma current (9MA instead of 21MA), with ITB to compensate the reduction of the confinement (∝Ip)!

•  Complex scenarios for pre-shaping the current density profile in the early phase of the ramp-up (physics of existing tokamak valid for ITER)!

ITER: current drive issues!

Rebut P.H., et al., Plasma Phys. Controlled Fusion 35 , A1 (1993).

!The CD efficiency (A/W) is too low to consider an operation of ITER tokamak completely based on a current generated by external means.!

!!A completely steady-state operation implies the existence of a low plasma current regime with an excellent confinement of energy: Advanced tokamak regime with a high fraction of the self-generated bootstrap (high ∇p, neoclassical effects). Highly non-linear regime !!

Ip = 18 MA, R = 8m!

ITER: non inductive current drive!

TORE SUPRA #30067: 4 minutes long discharge!

ITER : Indissociable physics & technology!•  Operation of superconducting tokamaks TORE SUPRA!

–  Control of transient events (disruptions).!•  Control of tritium cycle JET!

–  100 g injected and recovered!–  co-deposition: unsolved problem!

•  Development of robotics in vivo JET!•  Heating and current drive TORE SUPRA!

–  Neutral beam injectors!–  Development of rf sources, waveguide and antennas optimized at the

frequencies ICRF (Tetrodes), LH (klystrons/grill) et ECRF (gyrotron/mirrors).!

•  Plasma facing components (divertor, limiter, antenna protections) TORE SUPRA!

–  Development of materials having mechanical and thermal behaviors very different which are able to hold 5 to 10 MW.m-2 in continuous mode and up to 10 times more in transient (ELMs)… Behavior with extreme neutron fluences (IFMIF)

–  Breeder material facing the plasma (solid state physics problem), radioactive waste problem!

–  extraction of heat for the electrical production –  Extraction of Tritium from Lithium cycle!

LHCD and hot spots! LHCD and disruption!

Multimachine confinement time scaling !

15 G€!

ITER objectives !

• Q = 10 during 400 s (50 MW injected, 500MW fusion power)!• Continuous operation with Q = 5!• Show the reliability and the integration of essential

technologies for a fusion reactor (like the superconductive magnets and robotized maintenance)

• Test prototypes for tritium production (but no tritium production)

• Test new plasma facing components under high neutron fluence with low activation

ITER technology developments !

- ITER and the international fusion program -!

Elysée, Paris Novembre 21st

Iter in France

•  Participation in the construction and the operation of tokamak JT-60SA (in Naka, Japan)!

•  An international research center on fusion in Japan (IFERC: International Fusion Energy Research Center in Rokkasho) (studies and R & D for DEMO, center of simulation for Sciences of Fusion, center for ITER data processing)!

•  development of a neutron source of 14 Mev in Japan (IFMIF) !

•  ITER cost: Europe (50%), others contributors 10%!!!

ITER broad agreement !

January 2020 Iter in Cadarache…

January 2010

September 2010

January 2011

D+ Accelerator

Liquid Li Target

Neutrons (~1017n/s) Li Free

Surface

D+ Beam (10MW)

Specimens

IFMIF a 14 MeV neutron irradiation facility (International Fusion Material Irradiation Facility)

Radiation Damage in Fusion Materials

Neutrons Fusion Fission 14 MeV 2 MeV

Threshold reactions : ~100 times more hydrogen, helium

Swelling, embrittlement

59 University of Pavia, Italy, 4th March 2011 December 2009

IFMIF in Rokkasho

Septembre 2010 IFERC Rokkasho

New (Bucharest)

(Budapest)

(Prague)

Toroidal coil!

Central solenoid!

Chamber!

Blanket!Module + divertor!

Blanket + divertor! maintenance!

ITER: the industrial adventure is already started!

- Physics and integrated modeling -!

The modeling needs for Magnetic Fusion Devices (present tokamaks (RFP, stellarators), ITER, DEMO reactor) are manifold:!

•  « first principles » modeling:!•  Understanding the fundamental mechanisms!

•  « ad-hoc » modeling: !•  Developing simplified models, parameterized and adjusted both on experimental observations and first principle results. !•  Interpreting/predicting complex experimental behaviour. !•  Towards « integrated modeling »!

•  « real time » modelling: !•  Developing « ultra fast » modules for device control & operation!

•  « modeling technologies »!

L mode!–  Standard mode without divertor!

H mode (with divertor)!–  Edge transport barrier!–  Reference operation for ITER.!

Advanced modes!–  Specific pressure profiles

associated to appropriate safety factor profiles (q) lead to internal transport barriers (ITB)!

Pressure profile and plasma regime!

bootstrap

q-profile

Jbootstrap

pressure Jplasma

•  Non-inductive operation •  High Bootstrap current •  High confinement •  Real Time control

ITER Steady-State regime

•  Inon-inductive/Ip =100% •  Ibootstrap/Ip ≥ 60%

•  HH≥1.5 βN≥ 3.5

•  Reduced plasma current operation!•  Plasma self-generates most of its current needs : bootstrap current from steep pressure gradient (high βp regime, ITB)!•  Improved confinement: τE ∝ H×Ip!•  Self-organized regime: j ∝∇p!

Advanced tokamak concept for CW operation

Strong link between physics and numerics for fast and robust codes + advanced physics because of high ∇p (neoclassical theory, full wave, turbulence,etc)!

The plasma cannot be modelled without the systems that surrounds it: heating, current drive, injection of matter, wall, etc !!

+ !!To simulate the course of the experiment, implies to include controls !

Numerical tokamak

Plasma edge!(radiations, atomic physics, recycling)!

Wall/divertor!(Heat load,

chemistry, erosion, neutrons)!

Sources!(matter, current, heat, moment)!

Plasma core!(heat transport,

momentum transport, rotation)!

Current diffusion!+!

Magnetic equilibrium!!

Fusion power!

α particles modeling !

MHD (limits)!

Physical problems are strongly coupled

Integrated modeling (CRONOS, ASTRA, JETTO, ITM)!

Integrated modeling structure (CRONOS, ITM)

•  Modular organisation (separability approximation, time ordering) around transport solvers (particle, current, energy, three firt moments of the distribution)!

•  Several different levels of approximations for each module!

Self-consistent RF current drive C3PO/LUKE

The ray-tracing C3PO!

§  Separation between plasma dispersion models and the metric associated to the magnetic equilibrium!

∂Xsij

∂n⊥

∂n⊥∂Y

+∂Xs

∂n∂Y

+∂Xs

∂βTs

∂Xsij

∂ωps

∂Xsij

∂ωcs

Y = (X,k, t,ω)

∂Xsij

∂n⊥

∂n⊥∂Y

+∂Xs

∂n∂Y

+∂Xs

∂βTs

∂Xsij

∂ωps

∂Xsij

∂Ωs

kTs/msc2

ωps = ωps/ω Ωs = Ωs/ω

The Fokker-Planck solver LUKE!

§  Fully 3-D conservative formulation!

∂f (0)/∂t +∇ · S(0) = s(0)+ − s(0)

∇ ·S(0) =B0

B0∇ψS(0)

p2S(0)

∂ξ0

1− ξ20S(0)

∇ ·S(0) =B0

B0∇ψS(0)

p2S(0)

∂ξ0

1− ξ20S(0)

momentum space!

configuration space!

S(0) = −D(0) ·∇f (0) + F(0)f (0)

§  Linearized relativistic collision operator!§  Kennel-Engelman-Lerche rf diffusion operator!§  Non-uniform grids (f and fluxes)!§  Fully implicit time scheme: large time step Δt!§  Usual Chang & Cooper interpolation for p grid (fM)!§  Linear interpolation for radial and pitch-angle grids!§  Discrete cross-derivatives consistent with boundary conditions (stable scheme for Dql >> 1)!§  Generalized incomplete LU factorization technique for an arbitrary number of non-zero diagonals (highly sparse L and U matrices, low memory consumption)!§  written in MatLab!§  Iterative or direct inversion methods (MatLab build-in or external solvers MUMPS, PETSc, SUPERLU)!§  Distributed and parallel computing!

r2 > r1

r3 > r2

15d Radial dynamics

Momentum dynamics

Y. Peysson, J. Decker, and R. Harvey, 15th Top. Conf. on Radio Frequency Power in Plasmas, 2003, vol. 694 of AIP Conf. Proc., pp. 495–498.!

Linear limit validation (LH, EC)!

In the limit of low RF power level (D≈0), the result from the relativistic linear theory is well recovered!

LHCD in ITER (Scenario IV)!

-  n|| = 1.9!- n|| = 2.0!- n|| = 2.1!

GENRAY - CQL3D: 80 rays! C3PO - LUKE: 3 rays!

v||/c ∝ 1/n|| !

! Bonoli, P. T. et al., Proc. of the 21st IAEA Conference, Chengdu, 16-21 October 2006, 2006!

LHCD in ITER (Scenario IV)!

Almost linear single pass absorption leads to results that are almost independent of the number of rays ! (reduced computational effort)!

Integrated modeling of ITER steady-state scenarios (C3PO+LUKE in CRONOS)!

Garcia, J. et al., Plasma Phys. Control. Fusion, 2008, 50, 124032 !

§  More physics must be incorporated in simulations: fluctuations (turbulence), runaway avalanches in disruption, MHD driven by fast particles (e,α), etc!§  Beyond ray-tracing approximation → full-wave description for the LH wave (TORIC, ELECTRE-T)!§  bounce averaging → orbit averaging (Lie transform)!§  Kennel-Engleman-Lerche quasilinear operator should be replace by a full toroidal operator (Kaufman): wave-induced radial transport, consistent description of the rf and bootstrap currents, ion physics,…!§  electron back current calculations from non-Maxwellian ion distribution!§  LUKE 4-D for edge current drive physics ?!!

Heating current drive prospect!

- The ITER project - thermonuclear fusion for energy · tokamak regime at low plasma current (9MA...

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