On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. As recently reported, a burning plasma state, where the alpha-heating in the plasma is the primary source of heating, was achieved in laboratory experiments. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin ``burn propagation'' into surrounding cold fuel, enabling the possibility of high energy gain. While ``scientific breakeven'' (i.e. unity target gain) has not yet been achieved, this talk reports the first controlled fusion experiment on the National Ignition Facility to produce capsule gain greater than unity (here 5.8) and reach ignition by many different formulations of the Lawson criterion. In the talk, we will discuss some key basic physics inertial confinement fusion (ICF) principles behind the burning plasma and ignition results as well as discuss future challenges.

In this update lecture we focus on laser-driven instabilities in long scalelength underdense plasmas. Particular attention is given to some recent experiments on Raman scattering of intense laser light. Many important features are in accord with theoretical expectations. These features include a correlation of hot electron generation with Raman scattering, an increase in this scattering as the density scale length increases, and collisional suppression of the instability. Some challenging aspects of the growing data base as well as various deficiencies in the understanding are discussed. The role of the plasmon decay instability 2..omega../sub pe/, Brillouin, and filamentation instabilities is also briefly considered.

A new hohlraum geometry or “Frustraum” is proposed that may enable 2–3× higher capsule absorbed x-ray energy than for nominally sized capsules in standard cylinders. The Frustraum geometry comprises two truncated conical halves (or “frusta”) joined at the waist. An associated larger waist volume above the capsule allows fielding ∼50% larger capsules than the nominal 1 mm (radius) scale. A key feature of the Frustraum is that the outer laser cones strike the Frustraum ends at a higher glancing angle (by ∼23°) compared with a cylinder and generate more specular reflection. A scenario for boosted symmetry control from the outer cones reflecting off a glancing angle hohlraum wall depends on the choice of electron flux limit in the simulations. Recent data from the National Ignition Facility using oversized aluminum shells in rugby-shaped hohlraums [Ping et al., Nat. Phys. 15, 138 (2019)] come closest to approximating a Frustraum and are consistent with a flux limit of 0.03–0.04 in matching the simulated Dante drive history, the backlit trajectory of the Al shell, neutron yield, and implosion time. Applying this simulation methodology to hot-spot ignition designs in a Frustraum shows effective symmetry control and sufficient drive (∼290 eV) to enable high yield, moderate convergence implosions. Simulations suggest that adjusting the obliquity of the Frustraum wall is a robust lever for symmetry tuning. A high adiabat (α = 4.6) ignition design with a shortened laser pulse (<7 ns) is proposed to provide further margin to potential late-time loss of symmetry control from hohlraum filling and anomalous sources of fuel preheat.

Based on a graduate course in plasma physics taught at University of California, Davis, this classic book provides a concise overview and a physically-motivated treatment of the major plasma processes which determine the interaction of intense light waves with plasmas. It also includes a discussion of basic plasma concepts, plasma simulation using particle codes, and laser plasma experiments. This is the most elementary book currently available that successfully blends theory, simulation, and experiment, and presents a clear exposition of the major physical processes involved in laser-plasma interactions. This was also the first book on the topic by anyone involved in the United States Laser Fusion Program. Dr. Kruer has more than 30 years of active participation in this field.

Stimulated Raman scattering from multiple laser beams arranged in a cone sharing a common daughter wave is investigated for inertial confinement fusion (ICF) conditions in a inhomogeneous plasma. It is found that the shared electron plasma wave (EPW) process, where the lasers collectively drive the same EPW, can lead to an absolute instability when the electron density reaches a matching condition dependent on the cone angle of the laser beams. This mechanism could explain recent experimental observations of hot electrons at early times in ICF experiments, at densities well below quarter critical when two plasmon decay is not expected to occur.

We propose a novel method to minimize laser–plasma instabilities and improve laser–plasma coupling by the use of multi-beam laser architecture with a large system frequency bandwidth and many beamlets per unit solid angle. The StarDriver™, laser driver is constructed from 104 to 105 individual lasers, each delivering nominally 100 J in pulses of ~3–30 ns at a nominal wavelength of ~355 nm with better than 3–5 diffraction-limited performance. The beamlets are individually relatively narrowband to facilitate maximum laser performance, but the ensemble of beamlets span a wide frequency range. Currently available laser media enable Δω/ω ~ 2 % at 355 nm with the possibility of system bandwidths approaching 10 % in the future. The many beamlets of StarDriver™ provide optimal asymptotic smoothing for hydrodynamic instabilities (0–1 %), innovative focusing strategies including zooming, and the large bandwidth enables extremely rapid hydrodynamic smoothing times ~30 fs. The distribution of frequencies among the beamlets allows flexibility for fine control of the seeding of the Rayleigh–Taylor instability. The ultra-broad bandwidth combined with the large total k-spectrum of the laser drive in the plasma corona may enable complete suppression of the most problematic laser–plasma instabilities such as stimulated Brillouin backscatter, stimulated Raman scatter, cross-beam energy transfer, and the two plasmon decay instability. StarDriver™ offers potentially superior flexibility in laser drivers for inertial confinement fusion, enabling almost arbitrary sequencing of wavelength, polarization, focus, and fine control of the spatio-temporal properties of the drive in the corona. The highly modular strategy of StarDriver™ should enable an attractive development pathway as well as maximizing overall system efficiency.