Preheat in laser-driven experiments can have negative impacts on inertial confinement fusion (ICF) and hydrodynamic experiments. While many groups employ the use of dopants to reduce or block preheat, direct quantification has not previously been explored. We developed a planar platform and a series of ablator targets to measure the electron and x-ray spectra generated by laser-plasma interactions

This manuscript presents verification cases that are developed to study the electrothermal instability (ETI). Specific verification cases are included to ensure that the unit physics components necessary to model the ETI are accurate, providing a path for fluid-based codes to effectively simulate ETI in the linear and nonlinear growth regimes. Two software frameworks with different algorithmic approaches

We examine the performance of pure boron, boron carbide, high density carbon, and boron nitride ablators in the polar direct drive exploding pusher (PDXP) platform. The platform uses the polar direct drive configuration at the National Ignition Facility to drive high ion temperatures in a room temperature capsule and has potential applications for plasma physics studies and as a neutron source. The

The Marble campaign on the National Ignition Facility investigates the effect of heterogeneous mix on thermonuclear burn for comparison to a probability distribution function (PDF) burn model. Marble utilizes plastic capsules filled with deuterated plastic foam and a fill gas containing tritium. As the capsules implode, the deuterium in the foam mixes with the tritium gas, and DT neutrons are produced

The modeling of non-local-thermodynamic-equilibrium plasmas is crucial for many aspects of high-energy-density physics. It often requires collisional–radiative models coupled with radiative-hydrodynamics simulations. Therefore, there is a strong need for fast and as accurate as possible calculations of the cross-sections and rates of the different collisional and radiative processes. We present an

A long-standing ambiguity in spectral line broadening theory related to the electric field divergence in the quadrupole term of the screened Coulomb radiator-plasma interaction is examined. This is accomplished with multipole expansions from a Taylor series as well as a partial wave analysis of the screened Coulomb interaction. It is explicitly shown that the two approaches agree up to the octupole

The interaction of high-power short lasers with solid density targets is an important application of modern solid state lasers. However, uncertainties in measurements due to lack of information on the laser pedestal-to-peak contrast limits the validity of many conclusions. We show that X-ray spectral measurements can provide a straightforward way for accessing the laser pedestal-to-peak contrast. The

Radiation reaction (RR) is the frictional effect of a relativistically energetic and radiating electron. This situation can be created when the energetic electron collides with an ultra-intense laser pulse. We propose a RR experiment by making use of the collision of a 600 MeV electron beam from the linear accelerator and an ultra-intense laser pulse focused to 1022W/cm2 at ELI-NP. Its purpose is to

In fast ignition laser fusion, a high-intensity picosecond laser heats a compressed dense core to achieve ignition. It is theoretically expected that the energy coupling efficiency from the heating laser to the compressed core becomes higher as the wavelength of the heating laser is shorter. This prediction is ready to be experimentally demonstrated using second harmonic generation at Institute of

From experiments, we analyzed the spatiotemporal characteristics of a laser pulse in the Fourier plane in the 4-f arrangement. Based on these characteristics, we demonstrated two-stage frequency domain optical parametric amplification (FDOPA). The 275-fs signal seed pulse of the 1054-nm central wavelength was amplified in Type I β-BaB2O4 crystals pumped by a 180-ps pulse of 532-nm wavelength 532 nm

We present the results of the first Charged-Particle Transport Coefficient Code Comparison Workshop, which was held in Albuquerque, NM October 4–6, 2016. In this first workshop, scientists from eight institutions and four countries gathered to compare calculations of transport coefficients including thermal and electrical conduction, electron–ion coupling, inter-ion diffusion, ion viscosity, and charged

Laser fusion rocket can achieve large thrust and high specific impulse by utilizing huge amount of fusion energy to heat up a propellant. One of the issues of this system is heavy neutron shields which are heated by neutrons. The propulsion performance of a conical target that can reduce neutron radiation to the coil is calculated by numerical analysis. The impulse bits of the spherical and the conical

We conducted fast heating of a core plasma produced by counter-illumination of two beam bundles of implosion lasers for two incident directions of the heating laser. For the axial heating configuration, wherein the heating laser was incident along the coaxial direction of the implosion lasers, the size and density of the counter-imploded core plasma were estimated. The incident timing of the heating

A Ti:sapphire femtosecond laser with a relativistic intensity is focused onto a four-loop solenoid target to produce an ultrafast pulsed magnetic field. The magnetic field is generated due to a cold electron bunch which flows toward the laser focal spot to neutralize the remaining positive charge from the escaping hot electrons. The temporal evolution of the magnetic fields is evaluated by an improved

We evaluated the reconstruction quality from a conventional compressed ultrafast photography (CUP) system and demonstrated a multi-directional high-speed imaging system based on the CUP system. We evaluated the defect rate as a function of the reconstruction quality. The results showed that the dependence of the defect rate on the reconstruction quality is similar to that from numerical experiments

On shock ignition (SI) scheme of inertial confinement fusion (ICF), a spherical shell target is compressed by relatively low intensity laser pulse irradiation, and hot spot is ignited by converging shock waves by high intensity laser pulse called “spike pulse”. The SI scheme is considered as a promising scheme to reduce the required drive laser energy for ignition. On the SI scheme, the strong shock

Partition functions of a canonical ensemble of non-interacting bound electrons are a key ingredient of the super-transition-array approach to the computation of radiative opacity. A few years ago, we published a robust and stable recursion relation for the calculation of such partition functions. In this paper, we propose an optimization of the latter method and explain how to implement it in practice

The power and efficiency of terahertz radiation (THz) in a rippled density plasma by dark hollow laser beams are very small due to the collisional effect. We show that when a magnetic field is applied perpendicularly to the plasma, the THz radiation power and efficiency significantly enhance. Also, the magnetic field changes the THz radiation profile to a profile similar to a dark hollow laser beam

Ion acceleration with linearly polarized 1 petawatt (PW) intense laser pulses interacting with near critical density (NCD) gas targets was demonstrated by using two-dimensional (2D) particle-in-cell (PIC) simulations. The laser parameters considered are comfortably within the capabilities of PW laser facilities, e.g., Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Shanghai Superintense Ultrafast

Collisional effects on relativistic electron beam transport through high-density magnetized plasma are studied numerically and theoretically. An electron beam injected into cold high-density plasma induces the Weibel instability generating magnetic field components transverse to the direction of beam propagation. This field scatters the beam electrons. While an applied magnetic field suppresses the

Many experiments have been conducted at the National Ignition Facility to measure the equation of state Hugoniot of plastic, boron, and diamond at extreme pressures up to a Gbar. The “Gbar” design employs a strong spherically converging shock launched through a solid ball of material using a hohlraum radiation drive. The shock front conditions are characterized using X-ray radiography, typically at

Fuel areal density (ρR) of all recent indirectly driven, cryogenically-layered DT implosions at the National Ignition Facility (NIF) show a deficit when compared to simulations. Across all designs, experimental ρR is lower than in 1D simulations without alpha energy or momentum deposition. A series of layered implosions were fielded at NIF to assess the impact of fuel-ablator instability, as caused

An experiment has been conducted at the Shenguang-Ⅲ prototype laser facility, demonstrating the application of x-ray fluorescence imaging (XRFI) in diagnosing laser-driven hydrodynamic instability systems in planar geometry. An aluminum (Al)-foam target was used, including a modulated Al disk followed by a low density poly-4-methyl-1-pentene foam cylinder which was doped with titanium (Ti) dioxide

An iterative forward modeling approach has been developed and applied to the analysis of radiography data from cylindrical Rayleigh-Taylor instability studies performed at the Omega laser facility. Synthetic radiographs are generated and iterated using the Bayes’ Inference Engine [1] to produce maximum likelihood estimates for the time-dependent amplitude of deceleration-phase Rayleigh-Taylor modes

A laser-driven accelerator generates protons with tens of MeV in energy by a compact, strong, and transient accelerating electric field produced as a result of laser–plasma interactions at relativistic intensities. In previous studies, two- and three-dimensional particle-in-cell simulations revealed that the application of a kT-level axial magnetic field results in an enhancement of proton acceleration

Electromagnetic waves, in addition to the energy and momentum, can also carry an orbital angular momentum (OAM). Transfer of these quantities from laser to particles may find various applications. There are similarities between the process of OAM transfer from laser to electrons and a direct electron acceleration in a relativistic electromagnetic wave packet. In this paper, by using a numerical integration

The krypton-fluoride Nike laser delivers up to 2 KJ in 248 nm ultraviolet radiation to planar targets with the most uniform illumination of all existing high-energy lasers for inertial confinement fusion (ICF) research. That, combined with high-resolution monochromatic x-ray imaging pioneered at NRL in the 1990s and the recently added two-dimensional (2D) VISAR diagnostics, provides a unique platform

Studies on extreme ultraviolet (EUV) light sources for practical applications have attracted much attention. Although a laser-driven EUV source in conjunction with focusing mirrors enables the use of intense EUV radiation, mitigation of debris from the source plasma and focusing mirrors is a challenge to satisfy requirements for advanced material synthesis, because even a tiny amount of contamination

In recent years, laser peening technique has been used for the purpose of improving the fatigue strength of metal materials. However, the compressive residual stress field created by laser peening has characteristic differences in the stress value and the thickness of the stress field layer compared to conventional technologies. We conducted experiments to clarify the peening mechanism of metals when

We report on numerical simulations of laser-driven convergent plasma fusion targets. These “inverted corona” fusion targets are useful for the study of counter-streaming and converging rarefied plasma flows, and previous experiments have demonstrated their potential as neutron sources. The scheme consists of a fuel layer lined along the interior surface of a hollow plastic shell that is laser-ablated

The new Pulse Dilation – Photomultiplier Tube fielded on the Gas Cherenkov Detector GCD-3 at the National Ignition Facility allows for high band width DT gamma reaction history measurements. Crucial for successful data collection is precise timing of the dilation window. Using both a short pulse laser and test measurements on high yield ice layered DT shots the timing was set well within a 1-ns dilation

We experimentally studied electron beams and synchrotron x-ray radiation generated from the interaction of high-intensity picosecond laser pulses of 1–3 × 1019 W/cm2 with underdense plasmas of 1–8 × 1019 cm−3. Electron beams with maximum energy over 120 MeV, hundreds mrad divergence and tens of nC charge were generated in the experiments. The measured x-ray spectra were fit well with a synchrotron

Existing discrepancies between helioseismic data and solar models have questioned the accuracy of theoretical opacities for the solar interior. The opacities were further challenged by recent estimates claiming significant retardation effects, often neglected in opacity calculations, for radiative transitions relevant to the solar problem. Contrary to these claims, it is shown that the retardation

The interaction of an ultrashort laser pulse of moderate intensity ( ≳ 1018 W/cm2) with an innovative high-average-density target consisting of numerous sub-microwires was examined using 3D PIC simulations. We geometrically optimize the target to increase the absorption of laser light and energy (temperature) and the number of hot electrons. To explain the production of super-ponderomotive electrons

Frequency-resolved optical gating (FROG) is a novel means of measuring the fast motion of a critical density surface during relativistic laser–plasma interaction. Herein, we present a design and demonstration results for a new single-shot FROG system and optical transport system for characterizing the instantaneous intensity and phase at the LFEX (Laser for Fast Ignition Experiment) laser facility

We establish the work on white dwarf stars in the larger context of the experiments of the Wootton Center for Astrophysical Plasma Properties (WCAPP); these experiments are conducted at the plasma conditions found in the cosmos, without the need for scaling. We briefly summarize the results of these experiments to-date and their astrophysical and physical import, before focusing on the white dwarf

An experiment was performed at the National Ignition Facility investigating the ablative Rayleigh-Taylor instability’s dependence on initial conditions in the highly nonlinear stage. The detailed post-processing of the radiographic images which includes backlighter reconstruction, Wiener deconvolution of the raw data, and the calculation of a conversion factor from optical depth to physical units.

A combination of CR-39 track detectors and a stepwise energy filter is a simple method to measure the energy spectrum of laser-accelerated protons. The number of etch pits in each area of the CR-39 detector is expected to represent the energy spectrum because the different thicknesses of the filters result in different areas into which the energy reaches in CR-39. However, the higher energy regions

Usage of double-layer targets consisting of heavy and light material with modulated interface between them provides a way for laser-driven generation of collimated ion beams. With extensive 2D3V PIC simulations we show that this configuration may result in a development of a relativistic instability with Rayleigh-Taylor and Richtmyer-Meshkov like features. Initially small perturbations are amplified

In order to achieve the ignition by direct-drive inertial confinement fusion (ICF), smooth and symmetric fuel capsule is required. Our previous research found that stiffness of the capsule material contributes to reduce the laser imprinting. Therefore, diamond is considered to be the most promising candidate as the stiff ablator material for direct-drive ICF capsule. In this study, aiming at improving

We investigated radiation damages induced by irradiating ions in a particle accelerator for a heavy-ion inertial fusion (HIF) system, because the radio-activation is an unavoidable issue to realize the future HIF power plant. In this study, we estimated the radio-activation at each part of the HIF accelerator. An evaluation using collisions due to Coulomb barrier gives the safer estimation in the radio-activation

High power laser systems are an attractive driver for compact energetic ion sources. We demonstrate repetitive acceleration at 0.1 Hz of proton beams up to 40 MeV from a reeled tape target irradiated by ultra-high intensities up to 5 × 1021 Wcm−2 and laser energies ≈ 15 J using the J-KAREN-P laser system. We investigate the stability of the source and its behaviour with laser spot focal size. We compare

We present a systematic approach how to characterize the dynamics of a laser-produced Au plasma, generated with a commercial Joule-class laser system. By means of our diagnostic methods, we identify the dominant ionic species within the water-window spectral region, as well as the radiated energy, the x-ray emission duration and the total dimensions of the x-ray source. We present additional analysis

Efficient production of non-thermal hot electrons has been demonstrated experimentally by interactions of a plasma and two-color lasers with wavelengths of 527 and 1053 nm. The two-color-lasers and plasma interactions caused a 4.8 times enhancement of the temperature of the hot electrons and a 2.7 times enhancement of energy conversion from the lasers to the hot electrons compared with that obtained

A mechanism of isochoric heating of a solid density plasma by a kilojoule (kJ) class laser with relativistic intensity and a ten picosecond (ps) pulse duration is delineated by collisional Particle-in-Cell (PIC) simulations. Before an emergence of kJ class lasers, plasma heating by the laser-accelerated relativistic electron beam (REB) has been studied as the dominant isochoric heating process by intense

The kilo-tesla-class converging magnetic field effects on the core heating properties and the energy and duration of relativistic electron beam (REB) required for ignition in fast ignition laser fusion has been evaluated by parametric 2D hybrid simulations where a uniformly compressed DT core with ρ = 300 g/cm3 is heated by REB with TREB = 3 MeV, IREB = 0.69 × 1020 W/cm2 and θREB = 40° under sufficiently

Laser-driven ion acceleration attracts large attention due to variety of applications. In order to enhance accelerated proton energy and flux, we investigate the influence of laser-driven relativistic magnetic reconnection on the ion acceleration processes. In this relativistic regime, the longitudinal electric field becomes significantly enhanced and plays an important role in charged particle acceleration

Nonlinear interaction between bulk point vortices and the interface in the incompressible Richtmyer-Meshkov instability (RMI) is investigated theoretically and numerically. When the strength of point vortices are large enough, they interact with the original vorticity existing on the vortex sheet and create new vortex cores. These vortex cores roll up like mushrooms, and a very complicated interfacial

The Japan Establishment for a Power-laser Community Harvest (J-EPoCH) is proposed as a next generation laser facility having multi-purpose high repetition laser beams at the maximum rate of 100 Hz. One of the experimental areas is assigned for laser fusion research. The omnidirectional 12 laser beams with 8 kJ and a 5 PW heating laser are arranged. A Large High Aspect Ratio Target (LHART) with the

It is essential to properly shape the intensity distribution or irradiation field of high-energy charged-particle beams to improve their utilization, e.g., high energy density physics and heavy-ion fusion. Recently, unique beam profile shaping that cannot be realized through conventional linear focusing (i.e., the formation of hollow transverse profiles) was achieved through nonlinear focusing using

Interfacial instabilities in high-energy-density plasmas are important topics in various research fields such as inertial confinement fusion, planetary sciences, and astrophysics. The growth of the instabilities can be examined in the laboratory by using high-power lasers coupled with high-resolution imaging technique. The resolutions both in space and time are essential for the observation of tiny

Laser-driven neutrons have been expected as an optimum source for neutron radiography applications. Since the neutron fluence is lower than that of accelerator-based neutron source a new device for amplifying scintillation light has been required. The avalanche image intensifier panel discussed here has a large aperture and fast response which has been developed specifically for laser-driven neutron

The role of energy transfer by fast electrons, which is responsible for the positive effect of increasing the ablative pressure and the negative effect of preheating, on the implosion and thermonuclear gain of the target designed for shock ignition is investigated in comparison with the target designed for traditional spark ignition. On the base of one-dimensional hydrodynamic simulations with kinetic

To realize a pulsed-power discharge plasma using a liquid metal, we investigated the dependence of the diameter on the flow velocity of a liquid metal flow consisting of a U-alloy. The plasma temperature was measured using a pyrometric method. The results show that the flow velocity estimated by the parabolic corresponds to a theoretical value derived from the difference between the gas pressure and

The phenomenon of electron runaway in a dense semiclassical plasma was investigated on the basis of the effective potentials of particle interactions. These effective potentials take into account the quantum-mechanical effect of diffraction and static or dynamic screening. The results of numerical calculations of the effective collision frequency, mean free path and friction force for various values

This paper presents an exploration of potential mitigation methods for the gas fuel fill tube in Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF), and the impact of hydrodynamic growth seeded from other target imperfections using a specialized low convergence implosion experiment. Enhanced x-ray self- emission of this experiment design allows the impact of hydrodynamic

To clarify a regeneration process of fast electrons in a Malmberg-Penning trap device, a numerical simulation was carried out using a multi-particle tracking code. The numerical simulations reproduced the fast particle regeneration by the rapid relaxation process observed in the experiment. In comparison with the experimental and the numerical results, it was considered that the rapid relaxation process

In order to enhance the conversion efficiency of ultra-intense laser energy into plasma leading to ion acceleration, we have performed an experiment with over-picosecond laser pulses having a relativistic intensity interacting with foam targets. We adjust the prepulse of the laser to control the plasma density near the critical density. The combination of hydrodynamic and particle-in-cell simulations

Low-mode asymmetries represent an important obstacle to achieving high-gain inertial confinement fusion implosions. As a step in learning how to control such effects, an OMEGA experiment with imposed mode 2 laser drive asymmetries was done to study the expected signatures of this type of asymmetry [M. Gatu Johnson et al., PRE 2018]. In the present work, a 3D xRAGE simulation including the stalk mount

Radiation-hydrodynamics simulations are used to design laser-driven cylindrical implosion experiments to directly measure hydrodynamic instability growth in convergent geometry. Designs for two different size targets, varying in radial dimension by a factor of three, are presented. A set of beam pointings and powers are identified for each scale design that result in a nearly axially uniform implosion