Principles of Nuclear Fusion & Fusion research in Belgium R. R. Weynants Laboratorium voor Plasmafysica - Laboratoire de Physique des Plasmas Koninklijke Militaire School - Ecole Royale Militaire 1040 Brussels 1
Nuclear Fusion Is the energy-producing mechanism in the stars Each second about 600 million tons of hydrogen fuse in the Sun according to the net reaction 4 1 H 4 He + 2 e + + 2ν yielding 26.7 MeV / reaction (1 MeV = 1.6 10-13 J) This reaction asks for a temperature of 15 10 6 K. The power density of the sun is only 0.3 W/m 3. 2
Why is making a sun on earth so difficult? 1. To limit the reactor size a minimum power density of 1-10 MW/m 3 is required. Temperature T of order 100 million K Fuel density n high enough 2. The plant should deliver, at acceptable size, much more power P out than what it needs to run P in. Keep P in down by good thermal insulation of the reactor: Confinement time of energy τ Power amplification factor Q (=P out /P in ) should be high enough The Lawson criterium gives a necessary condition between T, n, τ and Q. 3. Harsh conditions (neutrons, heat) challenge technology, at high system complexity and capital cost. --> Continuing R&D (ITER, IFMIF) 3
Lawson Criterium A condition for energy economy Combines the parameters T, n, τ (triple product) and Q in a simple manner: n τ 60 k T 2 / ( <k r > E fus (1+5/Q) ). Q: power amplification factor k r : reaction rate coefficient Q = 1, breakeven, needs minimum nτ= 1x 10 28 m -3 sk, Q, ignition, needs minimum nτ= 6 x10 28 m -3 sk. 4
Why is it necessary/important to be pursued? Abundance and high energy density of fuels No greenhouse gases No critical or meltdown situations; accidents are self-limiting; public evacuation not necessary No long-lived radioactivity after shutdown (with inventory comparable to fission reactor) Ideal source for future base-load electricity 5
Fusion Fuels for D - T reaction : deuterium from water (0.02 % of all hydrogen is deuterium) -> unlimited lithium in the Earth s crust / in oceans -> reserves 2000 y / unlimited D + T 4 He + n 6 Li + n 4 He + T 7 Li + n 4 He + T + n Deu terium + Lithiu m Helium + Energy 1 gram of D-T gives 26000 kwh of electricity; 1 gram of coal gives 3Wh. 6
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HOW DOES IT WORK? Magnetic confinement provides insulation TOKAMAK 8
HOW DOES IT WORK? 8
HOW DOES IT WORK? Magnetic confinement provides insulation nt = τ = a 2 D β 2µ o B 2 nt τ B 3 a 2 E mag 1. E+0 1 1.E-0 1 1.E-0 3 Triple produ ct START ALC-C AUG ASDEX FT DIII-D ALC-A TEXTOR LHD W7-AS PLT TFR T10 COMPASS PULSATOR T3 JET C-MOD DIII-D TS JT-60 TFTR ITER ERASMUS Magnetic energy [J] 1.E-0 5 1. E+0 4 1. E+0 6 1. E+0 8 1. E+1 0 8
Fusion Research in Belgium Associatie EURATOM-Belgian State Physique Statistique et Plasmas (ULB) Staff : 14 Instit. f. Plasmaphysik Forschungszentrum Jülich (D) Staff : 100 LPP-ERM/KMS Staff : 35 SCK - CEN (Mol) Staff : 35 FOM -Rijnhuizen Nieuwegein (NL) Staff : 65 Trilateral Euregio Cluster 11
LPP-ERM/KMS specializes in heating by RF waves : Electric poloidal real Designs antennas and heating systems Optimises them Simulates their effects Constructs them for JET Plans them for ITER 10 (consortium led by LPP-ERM/KMS) (CYCLE consortium)
SCK CEN assesses fusion reactor materials under radiation Studies wall and structural metals under neutron fields Reduced activation steels Beryllium tiles and pebbles Copper cooling ducts Has a unique high flux material testing reactor, BR2 Broad capability in activated material testing Conducts Socio-Economics studies on public perception acceptability criteria Manages fusion waste Detritiation Disposal Makes radiation hardened instrumentation for diagnostics for remote handling units Conducts safety studies corrosion on structure hydrogen hasards 11
PSP- ULB studies transport processes in fusion plasmas Simulation of turbulent MHD flows (energy levels: red=high, blue=low) Particle trajectory simulations The particles are influenced by local electric&magnetic fields computed from magneto-hydrodynamic simulations Parallel computing: 100 interconnected desktop computers 12