The conversion of kinetic energy into heat is a possible approach to get the very high temperatures needed for controlled fusion. Various techniques leading to hypervelocities are considered. Some particular geometries and constitutions of liners allowing velocity amplification and superheating are described.

A two-dimensional simplified model of an HF chemical laser is introduced. Using an implicit finite difference scheme, the solution of two adjacent parallel streams with diffusion mixing and chemical reaction is generated. A contour of the mixing and reaction boundary is obtained without presupposition. The distribution of the HF(u) concentrations, gas temperature and the optical small signal gain (αu, J) on the flowing plane (X, Y) are presented. Compared with the solution solved directly from a set of Navier–Stokes equations, the results of these two methods agree with each other qualitatively. The influences of the different velocity, temperature (T0) and composition of the two streams on the small signal gain after the nozzle exit are investigated. It is interesting that for larger J with a fixed u, the peaks of αu, J—T0 profiles move towards higher T0. The computing method is simple and only a short computing time is needed.

In this paper we introduce designs that provide short duration megajoule pulses of ¼ micron wavelength light at efficiencies near ten percent.

In the absence of magnetic diffusion the self-generated magnetic field in a plasma is proportional to the fluid vorticity. The ratio of magnetic to fluid energy then shows that self-generated magnetic fields can only affect the Rayleigh Taylor growth rate for large k (wavelengths less then a few microns).

In the Bennett-Nordsieck self-pinched regime of high power REB propagation in a neutral atmosphere, radial expansion is generally associated with transverse entropy generation caused by elastic electron-neutral multiple scattering: LN ∝ 1/s′⊥ elast, where LN is the Nordsieck length, the distance for one e-folding of beam radius, and where s′⊥ elast is the elastic collision space rate of transverse mean entropy per particle.

For ultrarelativistic beams (γ ≳ 100), the bremsstrahlung, which is the dominant energy loss process, also plays an essential rôle in the radial expansion.

A general treatment could be based on the proper time evolution equation of the beam electron pressure 4-tensor pλμ (λ, μ = 0, 1, 2, 3) where source terms linked to elastic, inelastic and bremsstrahlung collisions are introduced, as is also a closure relation. This approach is currently being studied at LPPG.

When the various implied scale lengths have clearly different orders of magnitude, a much simpler approximate description may be given.

In the λmbrems < z < λstrbrems propagation distance range, where λmbrems is the depth threshold beyond which bremsstrahlung scattering becomes multiple, and λstrbrems a characteristic distance for bremsstrahlung straggling, the rôle of bremsstrahlung in radial expansion is similar to that of elastic multiple scattering. The calculated s′⊥ brems/s′⊥ elast increases rapidly with both propagation distance and beam electron energy. For γ ≫ 103, the bremsstrahlung transverse entropy source term s′⊥ brems is no more negligible before s′⊥ elast.

In the z > λstrbrems propagation distance range, where bremsstrahlung straggling is dominant, an evaluation of its effect is deduced by applying the Haftel–Lampe–Aviles criterion to a statistical study of this straggling. A completely different estimation, based on an oversimplified version of the above-cited general thermodynamic method, gives a result which is in rather good agreement.

Plasmas with long life times (∼20 ns) are generated in a cavity target by intense CO2 laser pulses (2 × 1014W/cm2). The plasma life depends on the configuration of irradiation and target, which may infer thermal conduction inhibition by the laser-generated magnetic field. The experimental results agree with those of computer simulations with magnetic inhibition of thermal conduction.

A high power KrF laser system employing beam multiplexing and stimulated Raman or Brillouin scattering to produce pulses as short as 1 ns and focused intensities on target of 1011 to 1014 W/cm2 has been developed for laser/plasma interaction research. A variety of investigations have been pursued on single and multilayer targets with variable atomic numbers. Absorption, transport, X-ray conversion, ion expansion characteristics, mass ablation and ablation pressure scaling, and stimulated scattering instabilities are among features that have been studied as a function of laser intensity. A wide variety of laser and target diagnostics are employed including focal plane imaging cameras for energy distribution and UV and soft X-ray streak cameras for temporally resolving the incident laser pulse and X-ray emission. Experimental results will be presented and our current understanding of the KrF laser/plasma interaction will be discussed.

This paper presents the multigigawatt single-beam CO2 laser system and the configuration and the main subsystems of the 0.5 TW four-beam CO2 laser system being built at the IPPLM. Selected construction details and early test results are given.

In this article the current capabilities at DENIM for the analysis of directly driven targets are presented. These include theoretical, computational and applied physical studies and developments of detailed simulation models for the most relevant processes in ICF. The simulation of directly driven ICF targets is carried out with the one-dimensional NORCLA code developed at DENIM. This code contains two main segments: NORMA and CLARA, able to work fully coupled and in an iterative manner. NORMA solves the hydrodynamic equations in a lagrangian mesh. It has modular programs coupled to it to treat the laser or particle beam interaction with matter. Equations of state, opacities and conductivities are taken from a DENIM atomic data library, generated externally with other codes that will also be explained in this work. CLARA solves the transport equation for neutrons, (Boltzmann), as well as for charged particles, and suprathermal electrons (Fokker-Planck), using discrete ordinates and finite element methods in the computational procedure. Parametric calculations of multilayered single-shell targets driven by heavy ion beams are also analyzed. Finally, conclusions are focused on the ongoing developments in the areas of interest such as: radiation transport, atomic physics, particle in cell method, charged particle transport, two-dimensional calculations and instabilities.

A model of quasars and their associated jets as phenomena of magnetic selfcompression is presented. Magnetic field self-compression, as observed in laboratory plasma focus devices, results in increases in energy density of more than 108 and in even larger increases in transferred power density. Our model, based on the scaling of these phenomena to astrophysical dimensions, avoids the problems of gravitationallyconfined approaches. It presents a mechanism by which the energy of a quasar is immediately derived from a volume nearly 106 times larger than the observed quasar radiating volume and is ultimately derived from the volume of an entire protogalactic plasma cloud. The model's predictions of quasar energy, radiated power, lifetime, dimensions, density and rotational velocity are in good agreement with observations. Part II of this paper extends the model to radio galaxies and briefly discusses the role of similar self-compression processes in the origin of filamentary super-clusters of galaxies.

A simple model Equation-of-State (EOS) for matter in conditions of interest to Inertial Confinement Fusion (ICF) and to Stellar Interiors is developed. It yields pressures and specific energies in good agreement with accurate EOS tabulations, for matter in the density range 10−6 < ρ < 104 g cm−3 and in the temperature range 0 ≤ T < 100 KeV, with the only exception being the liquid and gaseous phases of the undissociated molecular substances.

This EOS can be used for any element or mixture, requiring, as input data, only the chemical composition (A, Z, and abundancy of each element of the mixture) and three macroscopic constants of the material.

A model of quasars and radio galaxies and their associated jets is further elaborated here. The model, presented in Part I of this paper, is based on magnetic selfcompression as the process involved in producing extremely high energy densities. In the present paper, the results derived in Part I are used to predict radiation spectra from quasars, and to extend the model to radio galaxies. The role of magnetic self-compression of magnetic vortices in the origin of filamentary superclusters of galaxies is briefly discussed.

The wavelength scalings of soft X-ray and hot electron generation efficiencies were studied using 1·05, 0·53, 0·35 and 0·26 μm lasers. A coupling efficiency from absorbed laser energy to compressed fuel core of 4.5% was obtained by using the GEKKO XII green laser.

Aurora is a short-pulse high-power krypton-fluoride laser system that serves as an end-to-end technology demonstration prototype for large-scale ultraviolet laser systems of interest for short wavelength inertial confinement fusion (ICF) studies. The system is designed to employ optical angular multiplexing and serial amplification by electron-beam-driven KrF laser amplifiers to deliver 248 nm, 5-ns duration multi-kilojoule laser pulses to ICF targets using a beam train of approximately 1 km in length.

In this paper, we will discuss the goals for the system and summarize the design features of the major system components: front-end lasers, amplifier train, optical train, and the alignment and controls systems.

Both temporally and spectrally resolved fine structures of 90° lateral (3/2)ω0 harmonic emission were experimentally observed. The existence of (3/2)ω0 harmonic filaments is attributed to formation from the moving filament bottom at its transient nc/4 surface. The double hump structure with its intense red hump of laterally emitted (3/2)ω0 spectrum can also be explained by a Doppler correction in addition to the thermal correction. Estimation of both red and blue spectral shifts with our simple model is qualitatively consistent with experimental results. Experiments showed that the (3/2)ω0 emission was evidently suppressed by using a broad band laser. This may be promising for superhot electron suppression.

Calculations of the preheat of the cold region of an aluminum target by X-rays from the coronal region are presented. The computation was carried out by means of our 1-D hydrodynamics code, PLASMOR, which takes into consideration non-LTE steady state atomic physics. The radiation from the plasma is divided into 40 energy groups: 20 continuous groups (recombination + bremsstrahlung) from hv = 300 eV up to hv = 100 keV, and 20 lines, mainly (but not only) He-like and H-like lines. The hot coronal region is assumed to be optically thin to all radiation. The photoabsorption in the cold portion proceeds through the photo-ionization effect, and variations with density and temperature are taken into account by means of a simplified model. Black body radiative transport in the cold portion is also included. The effects of the radiation on the shock wave propagation as well as its influence on the density and temperature distribution in the shock compressed region were studied for trapezoidal and Gaussian laser pulse shapes.

Numerical analysis of the kinetics in an e-beam excited KrF laser medium demonstrates the feasibility of a compact KrF fusion driver operating at high intensity (∼100MW/cm2) and intrinsic efficiency (∼20%) in a Kr/F2 mixture. Some primitive concepts of KrF fusion driver modules are discussed.

A theoretical model of resonance absorption initiated by self-focusing filamentation is proposed on the bases of experiments on the 2ω0 time resolved spectrum, slow ion emission and filamentation of 3ω0/2 emission. A number of aspects of the experimental results can be well explained by this model.