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Fast ignition, a pivotal concept in inertial confinement fusion, presents a departure from conventional methods by implementing a two-stage process for fuel compression and ignition. This novel approach minimizes driver requirements and enhances energy efficiency. Among the primary solutions for initiating fast ignition, the utilization of light ion beams, specifically protons, generated through the interaction of high-power lasers with convertor foils, emerges as a prominent strategy. Investigation into the transport of alpha particles produced by the deuterium-tritium fusion reaction plays a vital role in the formation of a hot spot within the fast ignition framework. The self-heating effect caused by the energy deposition of alpha particles triggers ignition in the fusion fuel. Thus, this study focuses on exploring the impact of modern stopping power models, specifically BPS and MD, on the ignition criteria and hot spot formation of pre-compressed DT fuel using a two-temperature model in a non-equilibrium state. These new models are compared and contrasted with previous ones. For this investigation, a DT equimolar fuel with a density of 300 g cm–3 and an incident proton beam featuring an average energy of 4 MeV and a Maxwellian energy distribution are employed. Our calculations demonstrate that the newer BPS and MD stopping power models slightly shift the ignition criterion towards higher ρR values. Furthermore, the thermal efficiency reduction of alpha particles in these stopping power models leads to a significant decrease in hot spot temperature when compared to older models. [ABSTRACT FROM AUTHOR]

Focused Energy is a new startup company with the goal of developing laser-driven inertial fusion energy for electrical power production. The company combines the results from decades of fundamental research in inertial confinement fusion at universities and national laboratories with the flexibility and the speed of a startup company. Focused Energy has chosen the direct-drive, proton fast ignition approach to reach ignition, burn and high gain as the most promising approach. Located in Austin/US and Darmstadt/Germany, supported by the science community and private investment Focused Energy is paving the way to inertial fusion energy combining the best skill set and state-of-the-art technology from both sides of the Atlantic Ocean. In this paper we discuss the details and reasoning for the approach and the technical directions we have chosen. We will outline our roadmap for getting to a fusion pilot plant in the mid to late 2030s. [ABSTRACT FROM AUTHOR]

We present findings from an experimental tuning campaign aimed at igniting larger DT cryogenic layered implosions using a dual frustum shaped hohlraum, denoted "frustraum". The frustraum's distinctive shape reduces hohlraum wall losses while concurrently enhancing minimum capsule clearance with the hohlraum wall and sensitivity to pointing changes. Compared to current cylindrical hohlraum (6.4 × 11.24 mm), the frustraum has a wall area approximately 20 % smaller, resulting in a measured improvement in efficiency of around 12 %. Consequently, 12 % less laser energy is required to implode a capsule within the same acceleration timeframe. Conversely, directing the same laser energy into the frustraum yields higher ion temperatures within symmetry capsules, along with increased radiation temperatures and reduced implosion acceleration times compared to current cylindrical hohlraums. [ABSTRACT FROM AUTHOR]

Laser-driven "inverted corona" fusion targets have attracted interest as a low-convergence neutron source and platform for studying kinetic physics. The scheme consists of a hollow or gas-filled spherical shell made of deuterated plastic. The shell has one or more laser entrance holes (LEH), resembling a spherical hohlraum. The laser passes through the LEH's and illuminates the interior surface of the shell, ablating a plasma that travels inward towards the target center. Long ion mean free paths in the converging plasma can lead to significant interpenetration, atomic mix, and other kinetic effects. In this work we report on numerical simulations of inverted corona targets using the kinetic-ion, fluid–electron hybrid particle-in-cell (PIC) approach in 2D RZ geometry. 2D simulations suggest that shape effects do not have a significant impact on plasma evolution and observed yield trends are primarily the result of 1D kinetic mix mechanisms. Simulations are also compared against available experimental data recorded at the OMEGA laser facility. In particular, synthetic x-ray emission images show good qualitative agreement with experimental results, albeit with an apparent timing discrepancy for the two-sided vacuum target. More generally, we demonstrate the potential of hybrid-PIC simulations for full-system modeling and experimental design, including collisional absorption of laser energy, plasma evolution, mix, and fusion burn. [ABSTRACT FROM AUTHOR]

Fusion ignition by inertial confinement requires compression and heating of the fusion fuel to temperatures in excess of 5 keV and densities exceeding hundreds of g/cc. In August 2021, this scientific milestone was surpassed at the National Ignition Facility (NIF), when the Lawson criterion for ignition was exceeded generating 1.37MJ of fusion energy (Abu-Shawareb et al 2022 Phys. Rev. Lett. 129 075001), and then in December 2022 target gain >1 was realized with the production of 3.1MJ of fusion energy from a target driven by 2.0MJ of laser energy (Abu-Shawareb et al 2024 Phys. Rev. Lett. 132 065102). At the NIF, inertial confinement fusion research primarily uses a laser indirect drive in which the fusion capsule is surrounded by a high-Z enclosure (‘hohlraum’) used to convert the directed laser energy into a symmetric x-ray drive on the capsule. Precise measurements of the plasma conditions, x-rays, γ -rays and neutrons produced are key to understanding the pathway to higher performance. This paper discusses the diagnostics and measurement techniques developed to understand these experiments, focusing on three main topics: (1) key diagnostic developments for achieving igniting plasmas, (2) novel signatures related to thermonuclear burn and (3) advances to diagnostic capabilities in the igniting regime with a perspective toward developments for intertial fusion energy.

This paper provides neutronics analyses of the Xcimer Energy Corporation (XEC) HYLIFE-III Inertial Fusion Energy Power Plant concept. This design is based on the thick-liquid-wall HYLIFE-II reactor, but with much larger fusion yield, due to enhanced driver energy. Although HYLIFE-II neutronics was extensively studied, the differences between the two concepts suggested new analyses are required. Further, computational advances in neutronics calculations also motivate updating results from more than 25 years ago. The neutron spectra emitted from the much larger yield hybrid Inertial Confinement Energy (IFE) target is presented. Selected breeding materials are compared by tritium breeding ratio (TBR), activation, and first wall protection where FLiBe is proposed as the overall best choice. The first wall neutron activation and structural damage, including gas generation in the wall, is presented for various FLiBe protective wet-wall thicknesses. Final optic neutron damage is also examined and results in optics long enough lifespan with moderate annealing temperatures. Some limited comparisons of first wall damage for ICF and Magnetic Confinement Fusion relevant conditions is presented. HYLIFE-III with FLiBe as the breeding material and first wall protection provides a very robust TBR above 1.2. [ABSTRACT FROM AUTHOR]

Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity. A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide. Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition, the physics of fusion materials and advanced technologies for high-repetition-rate, high-average-power broadband lasers. We believe that the participation of the broader scientific community and the increased engagement of industry, in partnership with research and academic institutions, make most timely the construction of this infrastructure of extreme scientific attractiveness.

Fusion energy research is delivering impressive new results emerging from different infrastructures and industrial devices evolving rapidly from ideas to proof-of-principle demonstration and aiming at the conceptual design of reactors for the production of electricity. A major milestone has recently been announced in laser fusion by the Lawrence Livermore National Laboratory and is giving new thrust to laser-fusion energy research worldwide. Here we discuss how these circumstances strongly suggest the need for a European intermediate-energy facility dedicated to the physics and technology of laser-fusion ignition, the physics of fusion materials and advanced technologies for high-repetition-rate, high-average-power broadband lasers. We believe that the participation of the broader scientific community and the increased engagement of industry, in partnership with research and academic institutions, make most timely the construction of this infrastructure of extreme scientific attractiveness. [ABSTRACT FROM AUTHOR]

A simple model for the levelized cost of electricity (LCOE) of an inertial fusion power plant is developed. The model has 14 parameters. These have been designed to be technology agnostic, such that the model may be applied broadly to all variants of inertial fusion. It is also designed to allow easy use of proxies from existing technology. The variables related most intimately to the physics challenges of inertial fusion, such as gain and target cost, are treated as parameters such that requirements can be found without bringing complex physics into the model. A Monte Carlo approach is taken to explore the parameter space. The most important conclusion is that a combination of high gain (greater than 500) and high fusion energy yield per shot (greater than 5 GJ) together appear to unlock more cost competitive designs than those in the existing literature. Designs with LCOE as low as $25/MWh are found with optimistic but not obviously unrealistic inputs. This article is part of a discussion meeting issue 'Prospects for high gain inertial fusion energy (part 1)'. [ABSTRACT FROM AUTHOR]

Our research was mainly concentrated on the physics of semiconductor diodes and especially on measuring the reverse recovery times and currents. In addition, we explored the effect of the reverse bias pulses on a diode still under reverse recovery times. Therefore, we tested the diode cartridges only up to 40% of the scale of that of LANL. We utilized our Component Test Stand (CTS-I) facility modified to power two diode cartridges connected in parallel to a common load (CTS-II). We varied the charge voltage and interpulse separations between the two diode cartridges. In this article, we will describe the modifications of CTS leading to CTS-II and present and analyze the obtained results. [ABSTRACT FROM AUTHOR]

This paper investigates an analytical illustration of ignition conditions for the aneutronic reaction of proton-boron plasma in the presence of the magnetic field for fusion. In particular, the criterion for this plasma target is derived through two-temperature Lindl–Widner diagrams. Since the heating and cooling terms in the energy balance equation are affected by inequality between ions and electrons temperature combined with the impact of the magnetic field, the reduction of energy loss as well as the areal density parameter will increase the fusion rate. It will also relax the requirements of ignition conditions. Therefore, numerical derivations of ignition conditions at stagnation are performed involving the energy balance equation. The additional parameter applied other than electron and ion temperature as well as areal density is the magnetic field dependent B/ρ. It is shown that as B/ρ develops the required areal density decreases. For ions temperature of Ti < 1000 keV and electrons temperature of Te < 110 keV, the equation has real solutions for the areal density of ρR < 6 g/cm2. Furthermore, it is shown that the B/ρ parameter can be set at approximately 106 G cm3/g value. It shows the magnetic field has more effect than DT case and can reduce the driver requirements significantly. A comparison of this model with DT magnetized case shows that this model of p11B fuel is intermediate between experimental results of p11B non-magnetized and DT magnetized in the two-temperature model. [ABSTRACT FROM AUTHOR]

The supply of the required energy to achieve the fuel ignition is one of great concern in a fusion reactor. High amount of energy is needed for the ignition of 3He-3He fuel in a fusion reactor which is due to the losses of radiation and the requirement for high-temperature electrons and ions. The fast ignition (FI) approach causes a decrease in the laser power required to reach a large energy gain in an inertial confinement fusion (ICF) reactor. Ions have the benefit of having classical interaction through Coulomb dispersion with the background plasma. In this method, it is suggested to use deuteron beam for decreasing the ignition energy of the 3He-3He fuel. The deuteron particles would fuse with ions into fuel (helium-3) and produce additional energy. This excess energy has a considerable role in increasing energy gain in an 3He-3He fusion reactor. In this paper, the value of the energy efficiency coefficient (Y-value) and the total deposited energy are computed at different deuteron beam energy and electron temperature. The results show that Y-value is independent of helium-3 numerical density in the 3He-3He plasma and increases slowly with an increase in ion temperature. This fact is substantial at little deuteron energy and high electron temperature. • It is suggested deuteron beam for decreasing the ignition energy. • Depending on the conditions, the extra gain can attribute an important contribution. • The energy efficiency is independent of and increases slowly with increasing. T i. • The energy benefit of this scheme could be significant at less E D and further T e. • The energy dispersion and charge exchange must be considered for exact calculations. [ABSTRACT FROM AUTHOR]

The effects of different nuclear reactions on thermonuclear burn-up conditions of equimolar mixture of deuterium–tritium are investigated. The minimum requirements are determined by three parameters: fuel initial density, initial temperature and hot spot size. The four-temperature theory is used to calculate the critical burn-up parameter or the product of the initial density and the minimum hot spot radius. It was shown that by considering the effect of all nuclear reactions, attaining the minimum conditions required for beginning of nuclear ignitions is faster than those cases in which the effect of reactions is considered individually. [ABSTRACT FROM AUTHOR]

A recently published scheme for inertial fusion based on instantaneous heating of an uncompressed fuel is criticized. It is shown that efficient fusion and "time-like" fusion burn propagation cannot be realized due to the low nuclear reaction cross-sections. The suggested use of nanospheres inside the volume of the target to support the fast heating of the fuel is also questioned. [ABSTRACT FROM AUTHOR]

Calculations of accurate opacities in X and XUV range are of high interest for several domains such as astrophysics or inertial fusion science. Such quantities may be investigated through laser‐plasma interaction in the indirect‐drive scheme. In this work absorption properties of such plasmas are analysed using the Flexible Atomic Code. Detailed and unresolved‐transition‐array modes are investigated, and some results obtained with the mixed mode recently developed are also proposed. For a carbon plasma the present approach agrees with the results obtained with the superconfiguration code SCO. Some results are provided about the X‐ray opacity of nickel, and a comparison with data from a recent campaign on LULI 2000 facility is done. This comparison demonstrates that the Unresolved Transition Array approach may be insufficient, e.g., to determinate the accurate position and shape of the 2p–3d structure in nickel at about 25 eV. The case of non‐electric‐dipole‐type transitions, such as magnetic dipole transitions is addressed. The electric‐dipole and magnetic‐dipole transitions are studied here in the case of the 3 * n complex of five tungsten ions, with charge states similar to those found in the tokamak divertors. It is demonstrated that the unresolved transition array formulas provide a fairly accurate description of the most important absorption structures, but fail to reproduce correctly the behavior of the opacity in the wings of these main structures. [ABSTRACT FROM AUTHOR]

This paper provides a summary of recent research connected with the shock ignition (SI) concept of the inertial confinement fusion which was carried out at PALS. In the experiments, Cu planar targets coated with a thin CH layer were used. Two-beam irradiation experiment was applied to investigate the effect of preliminary produced plasma to shock-wave generation. The 1ω or 3ω main beam with a high intensity >1015 W/cm2 generates shock wave, while the other 1ω beam with the intensity below 1014 W/cm2 creates CH pre-plasma simulating the pre-compressed plasma related to SI. Influence of laser wavelength on absorbed energy transfer to shock wave was studied by means of femtosecond interferometry and measuring the crater volume. To characterize the hot electron and ion emission, two-dimensional (2D) Kα-imaging of Cu plasma and grid collector measurements were used. In single 1ω beam experiments energy transport by fast electrons produced by resonant absorption made a significant contribution to shock-wave pressure. However, two-beam experiments with 1ω main beam show that the pre-plasma is strongly degrading the scalelength which leads to decreasing the fast electron energy contribution to shock pressure. In both the single 3ω beam experiments and the two-beam experiments with the 3ω main beam, do not show any clear influence of fast electron transport on shock-wave pressure. The non-monotonic behavior of the scalelength at changing the laser beam focal radius in both presence and absence of pre-plasma reflects the competition of plasma motion and electron heat conduction under the conditions of one-dimensional and 2D plasma expansion at large and small focal radii, respectively. [ABSTRACT FROM AUTHOR]

In fast ignition research, a divergence of laser-generated hot electrons is a serious problem. Using diamond like carbon (DLC) cones is one of the realistic solutions to this problem. However, it is difficult to make a stand-alone DLC cone because it needs a thick DLC layer. In this paper, we report survey findings of preparation conditions for a thick DLC layer. DLC layers were prepared by using plasma–based ion implantation and deposition system. Acetylene gas or toluene vapor was used as a source. After trials of many deposition conditions, it is found that low gas pressure and low RF power condition is suitable for a thick DLC deposition. Properties of the made DLC layers were measured by near edge X-ray absorption fine structures (NEXAFS) and elastic recoil detection analysis (ERDA). It is found that these DLC layers have typical hydrogenated amorphous DLC properties. Based on these results, we succeeded in making stand-alone DLC cones. [ABSTRACT FROM AUTHOR]

Fast ignition is a new scheme for inertial confinement fusion (ICF). In this scheme, at first the interaction of ultraintense laser beam with the hohlraum wall surrounding a capsule containing deuterium-tritium (D-T) fuel causes implosion and compression of fuel to high density and then laser produced protons penetrate in the compressed fuel and deposit their energy in it as the ignition hot spot is created. In this paper, following the energy gain of spherical target and considering relationship of the burn fraction to burn duration, we have obtained the energy gain of conical targets characterized by the angle β, and found a hemispherical capsule (β=π/2) has a gain as high as 96% of that of the whole spherical capsule. The results obtained in this study are qualitatively consistent with Atzeni et al.'s studies of simulations.