Abstract
Indirect drive inertial confinement fusion experiments with convergence ratios below 17 have been previously shown to be less susceptible to Rayleigh–Taylor hydrodynamic instabilities, making this regime highly interesting for fusion science. Additional limitations imposed on the implosion velocity, in-flight aspect ratio and applied laser power aim to further reduce instability growth, resulting in a new regime where performance can be well represented by one-dimensional (1D) hydrodynamic simulations. A simulation campaign was performed using the 1D radiation-hydrodynamics code HYADES to investigate the performance that could be achieved using direct-drive implosions of liquid layer capsules, over a range of relevant energies. Results include potential gains of 0.19 on LMJ-scale systems and 0.75 on NIF-scale systems, and a reactor-level gain of 54 for an 8.5 MJ implosion. While the use of 1D simulations limits the accuracy of these results, they indicate a sufficiently high level of performance to warrant further investigations and verification of this new low-instability regime. This potentially suggests an attractive new approach to fusion energy.This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 2)’.
Highlights
Inertial confinement fusion (ICF) experiments, through extreme compression of deuterium– tritium (DT) fuel capsules, produce some of the most extreme conditions ever seen on Earth
In order to achieve fusion conditions, typical ICF experiments aim to compress the fuel as much as possible; in the National Ignition Campaign (NIC) at the National Ignition Facility (NIF), convergence ratios in the range of 30 < CR < 40 were targeted [3]. This resulted in the onset of significant hydrodynamic instabilities, which meant that fusion performance was significantly worse than expected from the campaign based on simulations
These instabilities were a key reason the NIC was unsuccessful in achieving ignition, and continue to be a major challenge in ICF experiments [4]
Summary
Inertial confinement fusion (ICF) experiments, through extreme compression of deuterium– tritium (DT) fuel capsules, produce some of the most extreme conditions ever seen on Earth. In order to achieve fusion conditions, typical ICF experiments aim to compress the fuel as much as possible; in the National Ignition Campaign (NIC) at the National Ignition Facility (NIF), convergence ratios in the range of 30 < CR < 40 were targeted [3] This resulted in the onset of significant hydrodynamic instabilities, which meant that fusion performance was significantly worse than expected from the campaign based on simulations. These instabilities were a key reason the NIC was unsuccessful in achieving ignition (along with fill tube, tent and capsule imperfections, all of which are exacerbated by high convergence ratio), and continue to be a major challenge in ICF experiments [4].
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