NIF Invited: Design of first fusion experiment to achieve target gain >1*

Andrea KRITCHER 

Lawrence Livermore National Laboratory, Livermore, CA 94550, USA

 

On August 8, 2021, ignition was finally demonstrated in the laboratory [1-3] on the National Ignition Facility (NIF) in Northern California in the HYBRID-E platform [4-5]. The experiment, N210808, produced a fusion yield of 1.37 MJ from 1.9 MJ of laser energy and has crossed the tipping-point of thermodynamic instability according to several ignition metrics.  N210808 burned about 2% of the initial DT fuel and showed variability to unintentional perturbations from changing capsule quality and odd mode asymmetries in follow-on experiments.  

 

Further improvements to the design on Dec 5th 2022 led to the first experiment to achieve fusion energy target gain >1 (N221204) and the highest neutron yield on NIF to date > 1x10¹⁸ and >3MJ of fusion energy produced.  These modifications include using ~8% more laser energy (2.05 MJ) to drive a thicker diamond ablator which provides more margin for ignition in the presence of perturbations [6-7], as well as higher fuel burn-up fraction by increasing the areal density of the DT fuel and ablator.  This talk will outline the design details of the first ever fusion experiment to achieve target gain > 1.          

 

 

[1] NIF collaboration, PRL, 129, 075001 (2022)

[2] Kritcher, et al., PRE, 106, 025201 (2022)

[3] Zylstra, et al., PRE, 106, 025202 (2022)

[4] Zylstra et al., Nature 601, 547 (2022)

[5] Kritcher et al., Nature Physics volume 18, 258 (2022)

[6] Kritcher et al, in progress (2023) 

[7] Hurricane et al., Phys. Plasmas 29, 012703 (2022