What is it about?

The work is aimed at evaluating a potential route to high "fusion energy-gain" in laser driven fusion experiments. Fusion energy-gain is a measure of energy efficiency, from laser input to fusion output, and is one of the single most important metrics for an experiment to become a future energy source. Energetic electrons generated in the so-called "shock ignition" scheme have been studied, and their effects quantified in terms of fusion energy-gain. The publication highlights the challenges due to the creation of a super thermal population of electrons (hot electrons), which are often overlooked or poorly modelled. The work also highlights potential mitigation strategies to the deleterious effects of such hot electrons, some of which are emerging in the literature/experiments.

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Why is it important?

Nuclear fusion at its core offers the ultimate energy solution. It provides a decentralized resource through Deuterium found in seawater, which helps prevent conflict zones and improve international energy security. Fusion plants do not have the large physical footprint of solar and wind and the reactants are inherently stable, making super-critical meltdown impossible. Similar to current nuclear fission reactors, they have the potential to be the zero carbon baseload or laser fusion in particular has the potential to vary output on a sub-minute timescale providing a high-value, demand dependent source. It is also one of the few energy sources renewable or otherwise capable of scaling with the predicted population growth.


Currently, there is no experimentally verified high gain method for creating fusion energy, and it is a strict requirement for energy production. Shock ignition offers potential in simulations, however it has never been tested at ignition scale. The paper uses state-of-the-art methods to highlight a potential challenge: hot electrons. Mitigation strategies are suggested in the discussion, which since/during publication are already being undertaken at experiments on the largest scales. See editorial summary by Scilight at link: https://doi.org/10.1063/10.0013820 Featured in Physics of Plasmas Early Career Collection 2022: https://doi.org/10.1063/5.0143348

Duncan Barlow

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This page is a summary of: Role of hot electrons in shock ignition constrained by experiment at the National Ignition Facility, Physics of Plasmas, August 2022, American Institute of Physics,
DOI: 10.1063/5.0097080.
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