Design of the first fusion experiment to achieve target energy gain G>1

A L Kritcher; A B Zylstra; C R Weber; O A Hurricane; D A Callahan; D S Clark; L Divol; D E Hinkel; K Humbird; O Jones; J D Lindl; S Maclaren; D J Strozzi; C V Young; A Allen; B Bachmann; K L Baker; T Braun; G Brunton; D T Casey; T Chapman; C Choate; E Dewald; J-M G Di Nicola; M J Edwards; S Haan; T Fehrenbach; M Hohenberger; E Kur; B Kustowski; C Kong; O L Landen; D Larson; B J MacGowan; M Marinak; M Millot; A Nikroo; R Nora; A Pak; P K Patel; J E Ralph; M Ratledge; M S Rubery; D J Schlossberg; S M Sepke; M Stadermann; T I Suratwala; R Tommasini; R Town; B Woodworth; B Van Wonterghem; C Wild

doi:10.1103/PhysRevE.109.025204

Design of the first fusion experiment to achieve target energy gain G>1

Phys Rev E. 2024 Feb;109(2-2):025204. doi: 10.1103/PhysRevE.109.025204.

Authors

A L Kritcher¹, A B Zylstra¹, C R Weber¹, O A Hurricane¹, D A Callahan¹, D S Clark¹, L Divol¹, D E Hinkel¹, K Humbird¹, O Jones¹, J D Lindl¹, S Maclaren¹, D J Strozzi¹, C V Young¹, A Allen², B Bachmann¹, K L Baker¹, T Braun¹, G Brunton¹, D T Casey¹, T Chapman¹, C Choate¹, E Dewald¹, J-M G Di Nicola¹, M J Edwards¹, S Haan¹, T Fehrenbach³, M Hohenberger¹, E Kur¹, B Kustowski¹, C Kong², O L Landen¹, D Larson¹, B J MacGowan¹, M Marinak¹, M Millot¹, A Nikroo¹, R Nora¹, A Pak¹, P K Patel¹, J E Ralph¹, M Ratledge², M S Rubery¹, D J Schlossberg¹, S M Sepke¹, M Stadermann¹, T I Suratwala¹, R Tommasini¹, R Town¹, B Woodworth¹, B Van Wonterghem¹, C Wild³

Affiliations

¹ Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808, USA.
² General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
³ Diamond Materials GmbH, 79108 Freiburg, Germany.

PMID: 38491565
DOI: 10.1103/PhysRevE.109.025204

Abstract

In this work we present the design of the first controlled fusion laboratory experiment to reach target gain G>1 N221204 (5 December 2022) [Phys. Rev. Lett. 132, 065102 (2024)10.1103/PhysRevLett.132.065102], performed at the National Ignition Facility, where the fusion energy produced (3.15 MJ) exceeded the amount of laser energy required to drive the target (2.05 MJ). Following the demonstration of ignition according to the Lawson criterion N210808, experiments were impacted by nonideal experimental fielding conditions, such as increased (known) target defects that seeded hydrodynamic instabilities or unintentional low-mode asymmetries from nonuniformities in the target or laser delivery, which led to reduced fusion yields less than 1 MJ. This Letter details design changes, including using an extended higher-energy laser pulse to drive a thicker high-density carbon (also known as diamond) capsule, that led to increased fusion energy output compared to N210808 as well as improved robustness for achieving high fusion energies (greater than 1 MJ) in the presence of significant low-mode asymmetries. For this design, the burnup fraction of the deuterium and tritium (DT) fuel was increased (approximately 4% fuel burnup and a target gain of approximately 1.5 compared to approximately 2% fuel burnup and target gain approximately 0.7 for N210808) as a result of increased total (DT plus capsule) areal density at maximum compression compared to N210808. Radiation-hydrodynamic simulations of this design predicted achieving target gain greater than 1 and also the magnitude of increase in fusion energy produced compared to N210808. The plasma conditions and hotspot power balance (fusion power produced vs input power and power losses) using these simulations are presented. Since the drafting of this manuscript, the results of this paper have been replicated and exceeded (N230729) in this design, together with a higher-quality diamond capsule, setting a new record of approximately 3.88MJ of fusion energy and fusion energy target gain of approximately 1.9.