Energy gain of wetted-foam implosions with auxiliary heating for inertial fusion studies

R. W. Paddock*, T. S. Li, E. Kim, J. J. Lee, H. Martin, R. T. Ruskov, S. Hughes, S. J. Rose, C. D. Murphy, R. H.H. Scott, R. Bingham, W. Garbett, V. V. Elisseev, B. M. Haines, A. B. Zylstra, E. M. Campbell, C. A. Thomas, T. Goffrey, T. D. Arber, R. AboushelbayaM. W. Von der Leyen, R. H.W. Wang, A. A. James, I. Ouatu, R. Timmis, S. Howard, E. Atonga, P. A. Norreys*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Low convergence ratio implosions (where wetted-foam layers are used to limit capsule convergence, achieving improved robustness to instability growth) and auxiliary heating (where electron beams are used to provide collisionless heating of a hotspot) are two promising techniques that are being explored for inertial fusion energy applications. In this paper, a new analytic study is presented to understand and predict the performance of these implosions. Firstly, conventional gain models are adapted to produce gain curves for fixed convergence ratios, which are shown to well-describe previously simulated results. Secondly, auxiliary heating is demonstrated to be well understood and interpreted through the burn-up fraction of the deuterium-tritium fuel, with the gradient of burn-up with respect to burn-averaged temperature shown to provide good qualitative predictions of the effectiveness of this technique for a given implosion. Simulations of auxiliary heating for a range of implosions are presented in support of this and demonstrate that this heating can have significant benefit for high gain implosions, being most effective when the burn-averaged temperature is between 5 and 20 keV.

Original languageEnglish
Article number025005
Number of pages10
JournalPlasma Physics and Controlled Fusion
Issue number2
Early online date27 Dec 2023
Publication statusPublished - Feb 2024

Bibliographical note

Funding Information:
The authors gratefully acknowledge the support of the staff of the Central Laser Facility and Scientific Computing Department, UKRI-STFC Rutherford Appleton Laboratory and the Orion laser facility at AWE plc in support of this work. They would also like to thank R S Craxton for his detailed comments on the manuscript, along with with T J B Collins, V N Goncharov, J T Larsen and R Manson-Sawko for a number of useful discussions. This work was supported by the 0014023 STFC IAA Starter/Accelerator Fund grant and the John Adams Institute Grant ST/V001655/1.

Publisher Copyright:
© 2023 The Author(s). Published by IOP Publishing Ltd.


  • auxiliary heating
  • inertial fusion
  • low convergence ratio

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