ELI summer school, August 26 – 30, 2019
Academic research on the inertial confinement thermonuclear fusion in Europe
V. T. Tikhonchuk Centre Lasers Intenses et Applications, University of Bordeaux – CNRS – CEA, Talence, France ELI-Beamlines, Institute of Physics, CSR, Dolní Břežany, Czech Republic Principles of initial confinement fusion for energy production (IFE)
IFE is a pulsed process: the energy is released in periodic pellet explosions • Standard power plant produces 1 GW = 1 GJ/s: 1 GW = 10 explosions in 1 s = 250 kg TNT/s = 3 mg DT/s • Typical target mass is 1 mg corresponds to a sphere R = 1 mm at normal density ρ = 0.25 g/cc
Ignition conditions are imposed by the Lawson criterion: ρR > 0.3 g/cm2 at T = 5 keV It cannot be satisfied at normal conditions: compression and heating are needed • compression of the total fuel mass by using the ablation pressure: recoil effect • heating of a small part of the fuel: creation of a spark (hot spot) • combustion of the residual fuel
August 30, 2019 Academic research on ICF in Europe 2 Three steps of the ICF process:
• compression of the total fuel mass by using the ablation pressure: recoil effect • heating of a small part of the fuel: creation of a spark (hot spot) • combustion of the residual fuel
• implosion time 10 ns • driver energy 1 MJ • ignition time 30 ps • gain 300 • acceleration 1013g • final energy 50 kJ • radius 100 µm • fusion energy • pressure 100 Mbar • efficiency 5% • pressure 300 Gbar 300 MJ • implosion velocity ~ • energy 10 kJ 400 km/s
August 30, 2019 Academic research on ICF in Europe 3 Two basic approaches: direct and indirect drive
direct drive indirect drive
ablator DT ice DT gas R
R ~ 1 mm ~ 0.2 mm
• indirect drive is motivated by the national defence programs: less efficient but considered to be more reliable • direct drive: academic program is motivated by energy production and modelling extreme states of matter in laboratory
August 30, 2019 Academic research on ICF in Europe 4 Only few large scale laser installations exist in the world
direct drive indirect drive
OMEGA LMJ NIF 60-beams, 30 kJ, 30 TW 176-beams, 1.4 MJ, 400 TW 192-beams, 1.8 MJ, 500 TW
direct drive: fast ignition Academic programs benefit a free access to the national MJ facilities on a competitive basis within ~15% of the
GEKKO XII available shots 12-beams, 10 kJ, 10 TW SHENGUANG-III 48-beams, 180 kJ, 60 TW August 30, 2019 Academic research on ICF in Europe 5 Update on the indirect drive experiments Indirect Drive ignition experiments are conducted on NIF since 2009 Several approaches are considered: Major problems: • low adiabat (low foot) implosions (2010 – 2012) • low energy coupling to the hot spot • medium adiabat (high foot) implosions with plastic • hydrodynamic instability of the and HD carbon ablators imploding shell • low gas fill hohlraums (symmetry control) • low energy coupling to hohlraum
O Hurricane et al, Phys Plasmas 2019 Significant progress but still far from ignition
August 30, 2019 Academic research on ICF in Europe 6 Outline
. Direct drive ignition program and role of the European scientific community . Alternative approaches to inertial fusion: fast and shock ignition . Recent developments in the fast ignition approach: magnetic guiding of electrons . Strong shock generation experiments in the planar and spherical geometry: role of hot electrons . Near future plans
August 30, 2019 Academic research on ICF in Europe 7 Direct drive approach: more efficient energy deposition
The ignition conditions impose a relation between the hot spot pressure and energy . ⁄ By using relations between the energy pressure and radius: