Speaker
Descrizione
To achieve laser driven nuclear fusion, a pellet of hydrogen isotopes is
imploded in reaction to an expanding plasma, ablated by the laser. The
implosion is subject to hydrodynamic instabilities, while laser-plasma
instabilities (LPI) occur in the expanding plasma. These instabilities
are two of the greatest challenges faced when designing suitable
implosions for laser fusion experiments. Each instability can be
evaluated numerically but requires expensive computations that can
become prohibitive on the timescales required by the implosion. A new
methodology employs temporally discretised evaluations and simple
physics based approximations to enable fast and accurate illumination
design of experiments at existing laser facilities [1].
Major breakthroughs in laser fusion experiments have led to significant
public and private funding around the world [2]. Within France, the
Taranis project led by Genf is aiming to create a laser fusion reactor
to produce electrical energy. In order to achieve the necessary
implosion stability, a reactor would require hundreds or thousands of
laser beams, each with carefully selected parameters. The enormous
parameter space and the expense of numerical evaluation is a significant
challenge for design of future facilities.
This talk presents a new methodology for creating and evaluating the
drive configuration of beams for future laser facilities. A
state-of-the-art ray-tracing tool [3] is employed alongside automated
optimization to create novel illumination geometries while considering
the impact of the LPI cross-beam energy transfer, beam spot shapes,
bandwidth and wavelength. This technology is a critical step towards
fusion energy, furthermore it creates opportunity for designing a
greater variety of experiments at current facilities, and evaluating LPI
thought too computationally expensive for prior methods.
References:
[1] Barlow, D. et al. “Optimization Methodology of Polar Direct-Drive
Illumination for the National Ignition Facility” Physical review
letters 133, (2024) 175101.
[2] Abu-Shawareb, H., et al. "Lawson criterion for ignition exceeded in
an inertial fusion experiment." Physical review letters 129.7 (2022):
075001.
[3] Colaïtis, A, et al. "Adaptive inverse ray-tracing for accurate and
efficient modeling of cross beam energy transfer in hydrodynamics
simulations." Physics of Plasmas 26.7 (2019).
