This paper studies the surface plasma wave excitation via Cerenkov and fast cyclotron interaction by a density modulated electron beam propagating through a magnetized dusty plasma cylinder. The dispersion relation of surface plasma waves has been derived and it has been shown that the phase velocity of waves increases with increase in relative density δ(= nio/ne0, where ni0 is the ion plasma density and ne0 is the electron plasma density) of negatively charged dust grains. The beam radius is taken slightly less than the radius of dusty plasma cylinder. The frequency and the growth rate of the unstable wave instability increases with increase in the value of δ and normalized frequency ω/ωpe. The growth rate of the instability increases with the beam density and scales as one-third power of the beam density in Cerenkov interaction and square root of beam density in fast cyclotron interaction. The dispersion relation of surface plasma waves has been retrieved from the derived dispersion relation by considering that the beam is absent and there are no dust grains in the plasma cylinder.

A non-collinear laser beam combination based on Brillouin amplification is proposed. The influence of non-collinear Brillouin amplification on the combination efficiency is analyzed and discussed theoretically. It is shown that an efficiency of 80% can be achieved with the angle between the Stokes and the pump limited to a range of 10°. The theoretical prediction is tested in experiment of non-collinear amplification of one Stokes and one pump. A two-beam combination scheme is designed and a high combination efficiency of 80% is also obtained in this experiment. According to these results, a 20-beam combination scheme is designed to achieve 13.2-J output energy. A very simple construction for a multiple beams combination is designed.

The LIBRA light ion beam fusion commerical reactor study is a self-consistent conceptual design of a 330 MWe power plant with an accompanying economic analysis. Fusion targets are imploded by 4 MJ shaped pulses of 30 MeV Li ions at a rate of 3 Hz. The target gain is 80, leading to a yield of 320 MJ. The high intensity part of the ion pulse is delivered by 16 diodes through 16 separate z-pinch plasma channels formed in lOO torr of helium with trace amounts of lithium. The blanket is an array of porous flexible silicon carbide tubes with Li17Pb83 flowing downward through them. These tubes (INPORT units) shield the target chamber wall from both neutron damage and the shock overpressure of the target explosion. The target chamber is a right circular cylinder, 8·7 meters in diameter. The target chamber is ‘self-pumped’ by the target explosion generated overpressure into a surge tank partially filled with liquid that surrounds the target chamber. This scheme refreshes the chamber at the desired 3 Hz frequency without excessive pumping demands. The blanket multiplication is 1·2 and the tritium breeding ratio is 1·4. The direct capital cost of LIBRA is estimated to be $2200/kWe.

Spatial confinement effects on plasma parameters and surface morphology of laser-ablated Mg are studied by introducing a metallic blocker as well as argon (Ar) gas at different pressures. Nd: YAG laser at various fluences ranging from 7 to 28 J/cm2 was employed to generate Mg plasma. Confinement effects offered by metallic blocker are investigated by placing the blocker at different distances of 6, 8, and 10 mm from the target surface; whereas spatial confinement offered by environmental gas is explored under four different pressures of 5, 10, 20, and 50 Torr. Laser-induced breakdown spectroscopy analysis revealed that both plasma parameters, that is, excitation temperature and electron number density initially are strongly dependent upon both pressures of environmental gases and distances of blockers. The maximum electron temperature of Mg plasma is achieved at Ar gas pressure of 20 Torr, whereas maximum electron number density is achieved at 50 Torr. It is also observed that spatial confinement offered by metallic blocker is responsible for the significant enhancement of both electron temperature and electron number density of Mg plasma. Maximum values of electron temperature and electron number density without blocker are 8335 K and 2.4 × 1016 cm−3, respectively, whereas these values are enhanced to 12,200 K and 4 × 1016 cm−3 in the presence of blocker. Physical mechanisms responsible for the enhancement of Mg plasma parameters are plasma compression, confinement and pronounced collisional excitations due to reflection of shock waves. Scanning electron microscope analysis was performed to explore the surface morphology of laser-ablated Mg. It reveals the formation of ripples and channels that become more distinct in the presence of blocker due to plasma confinement. The optimum combination of blocker distance, fluence and Ar pressure can identify the suitable conditions for defining the role of plasma parameters for surface structuring.

An approach to produce efficient and economical hydrogen, which is one of the solutions of future energy, by inertial fusion energy reactor is discussed. This fusion reactor is with magnetic field such as mirror machine and graphite solid blanket. Neutrons and charged particles from nuclear reactions are separated from each other by this magnetic field. This results in hydrogen production efficiently in a solid blanket of high temperature with a breakeven of electricity by direct conversion of charged particle. The output of hydrogen may meet not only economical issue but also ecological issues.

A three-dimensional model to calculate X-ray intensity distribution on an indirectly driven fusion target is presented. The model includes conversion of laser light into X rays, radiation reemission from X-ray-heated wall of a cavity, and influence of an inner pellet (i.e., a fuel capsule) on radiation redistribution. Intensity distribution of an X ray inside a cylindrical cavity heated by intense blue laser light (wavelength 351 nm, energy 5.2 kJ, duration 0.7 ns) was determined by measuring a burn-through signal from a diagnostic foil integrated onto the cavity. The experimental result is well replicated by the model calculation. By using this model, optimum conditions for uniform irradiation of afusion capsule by X-ray radiation are evaluated for use in Gekko XII laser fusion experiments.

The effect of laser fluence and nature of ambient environments on the sputtering yield, surface modifications, crater depth, UV-visible absorption spectra, chemical composition, and micro hardness of Zr has been investigated. Nd: YAG laser (532 nm, 10 Hz, 6 ns) at different fluences varying from 16 to 60.8 Jcm−2 was employed as an irradiation source. All measurements are performed under two ambient environments of Ar and O2 at a constant pressure of 10 Torr. Quartz crystal microbalance has been employed for the measurement of sputtering yield of laser irradiated Zr. It is revealed that sputtering yield increases monotonically with increasing fluence under both environments however, it is higher in Ar as compared to O2 environment. Scanning electron microscope (SEM) has been used to explore the surface morphology. SEM analysis exhibits the formation of cones, ridges, and cracks at the central ablated areas whereas, laser-induced periodic surface structures, periodic ridges and sharp cones are observed at inner boundaries in both environments of Ar and O2. Sharp spikes are observed in both environments, however, their height and distinctness are more pronounced in Ar as compared to O2. Cones are characteristic features in Ar, whereas, cavities and channels are dominant features in O2 environment at outer boundaries. The formation and growth of surface structures are dependent upon laser fluence and ambient gas nature. The depth profilometry has been used to measure the crater depth of irradiated Zr target by using an optical microscope. UV visible spectroscopy and energy-dispersive X-ray analyses reveal the oxide formation in the case of Zr irradiation in O2 environment. The Vicker Micro-hardness tester has been employed to measure the hardness. The higher observed values of sputtering yield, crater depth and hardness of laser ablated Zr in Ar as compared to O2 are well correlated with distinct surface structures.

In order to improve the optical limiting performance based on stimulated Brillouin scattering (SBS), a combination of SBS and carbon nanotube/HT-270 suspension for optical limiting is proposed in this paper. The dependence of output energy of optical limiting based on this hybrid approach on the pump energy is numerically simulated, and validated in Continuum's Nd: YAG seed-injected laser. The results indicate that the output energy based on this hybrid approach shows much better performance compared with that based on single SBS. In this approach, the SBS threshold can be controlled by adjusting the gain coefficient of medium and focal length of the lens, and the threshold of suspension can be controlled by altering the concentration and focal length of the lens, therefore, this hybrid approach to realize optical limiting has great potential in practical application.

Stimulated Raman forward scattering (SRFS) of an intense X-mode laser pump in a preformed parabolic plasma density profile is investigated. The laser pump excites a plasma wave and one/two electromagnetic sideband waves. In Raman forward scattering, the growth rate of the parametric instability scales as two-third powers of the pump amplitude and increases linearly with cyclotron frequency.

In this paper, the results of an experimental investigation of dust formation in a pulsed plasma accelerator, which is formed due to the interaction of a pulsed plasma flow with the candidate material of the thermonuclear reactor, are presented. Dynamic and optical properties of a pulsed plasma flow are considered. The results of the synergetic analysis by the Raman spectrometer of the target surface after irradiation with plasma are also presented. It was revealed that after interaction with the plasma, the surface of the graphite target becomes amorphous. Materials with fractal surfaces, similar to the materials formed in tokamaks under the action of erosion, were obtained experimentally. Using a high-speed camera Phantom v2512 video shooting of the plasma beam was carried out, during which it was revealed that the pulsed plasma beam has a speed of about 23 km/s.

This article presents a numerical and theoretical study of the generation and propagation of oscillation in the semiclassical limit ħ → 0 of the nonlinear paraxial equation. In a general setting of both dimension and nonlinearity, the essential differences between the “defocusing” and “focusing” cases are observed. Numerical comparisons of the oscillations are made between the linear (“free”) and the cubic (defocusing and focusing) cases in one dimension. The integrability of the one-dimensional cubic nonlinear paraxial equation is exploited to give a complete global characterization of the weak limits of the oscillations in the defocusing case.

Aiming breakeven for nuclear fusion energy needs a more than 1000 times higher fusion gain. This may be achieved as the anomalously high jump of gains known from the discovery of volume ignition since 1978. This is considered for combination with the present most advanced experiments at the world highest class laser of NIF.

The results from theoretical and experimental studies, as well as from 2.5-dimensional (2.5-D) numerical simulation of plasma wake field excitation, by either relativistic electron bunch, laser pulse, and the charged particle wake field acceleration are discussed. The results of these investigations make it possible to evaluate the potentialities of the wake field acceleration method and to analyze whether it can serve as a basis for creating a new generation of devices capable of charged particle accelerating at substantially higher (on the order of two to three magnitudes) rates in comparison with those achievable in classical linear high-frequency (resonant) accelerators.

We address the issues of collective stopping for intense relativistic electron beams (REB) used to selectively ignite precompressed deuterium + tritium (DT) fuels. We investigate the subtle interplay of electron collisions in target as well as in beam plasmas with quasi-linear electromagnetic growth rates. Intrabeam scattering is found effective in taming those instabilities, in particular for high transverse temperatures.

A method for the automatic, discrete rezoning of two-dimensional Lagrangian codes for inertial confinement fusion (ICF) implosions has been developed. The method, which applies to matrix-ordered, quadrilateral zone meshes, allows the preservation of the interface tracking property of the Lagrangian approach. Total mass and momentum are conserved exactly, total energy is approximately conserved, and numerical diffusion is kept to tolerable levels. The mesh generator, the mapping scheme, and the actual implementation in a two-temperature laser fusion code are described. The performance of the method is illustrated by several sample applications.

The electromagnetic simulation of the monolithic radial transmission lines for future Z-pinch was performed. Focusing on the difference in the maximum transmitted power efficiency between the electromagnetic simulation and the circuit simulation, the monolithic radial transmission lines with different impedance profile (exponential, Gaussian, hyperbolic) were compared. The power efficiency for the exponential line is higher than that for the Gaussian lines and the hyperbolic line, which is similar to that from the circuit simulation. However, all the power efficiencies obtained with the electromagnetic simulation are about 15% lower than those obtained with the circuit simulation, indicating the existence of considerable non-TEM modes and a non-ignorable error in the circuit simulation based on the quasi-TEM mode approximation. In consideration of several monolithic radial transmission lines being stacked together and the flat electrodes required by the stacked lines, the hyperbolic line was compared with the exponential line with several wide radial slots cut on the flat electrodes. While the hyperbolic line has a little bit lower transmitted power efficiency than that of the exponential line, it is much easier in fabrication. For this reason, the hyperbolic line was recommended as the best choice.

Significant experimental and theoretical progress has been made in the U.S. heavy ion fusion program on high-current sources, transport, and focusing. Currents over 200 mA have been transported through a matching section and 10 half-lattice periods with electric quadrupoles. An experiment shows control of high-beam current with an aperture, while avoiding secondary electrons. New theory and simulations of the neutralization of intense beam space charge with plasma in various focusing chamber configurations predict that near-emittance-limited beam focal spot sizes can be obtained even with beam perveance (ratio of beam space potential to ion energy) >10× higher than in earlier HIF focusing experiments. Progress in a new focusing experiment with plasma neutralization up to 10−3 perveance, and designs for a next-step experiment to study beam brightness evolution from source to target are described.

A large amplitude Trivelpiece–Gould (TG) mode, in a strongly magnetized beam–plasma system, parametrically couples to a beam space charge mode and a TG mode sideband. The density perturbation associated with the beam mode couples with the electron oscillatory velocity, due to the pump wave, to produce a nonlinear current, driving the sideband. The pump and the sideband waves exert a ponderomotive force on the electrons with a component parallel to the ambient magnetic field, driving the beam mode. For a pump wave having k0·v0b0/ω0 < 0, where ω0, k0 are the frequency and the wave number of the pump, and v0b0 is the beam velocity, the sideband is frequency upshifted. At low beam density (Compton regime) the growth rate of the parametric instability scales as two-thirds power of the pump amplitude, and one-third power of beam density. In the Raman regime, the growth rate scales as half power of beam density and linearly with pump amplitude. The background plasma has a destabilizing role on the instability.

Dynamics and organization of laser-generated three-dimensional (3D) Richtmyer–Meshkov (RMI) and Rayleigh–Taylor instabilities (RMI and RTI) on metal target in the semiconfined configuration are different in the central region (CR) (Lugomer, 2016), near central region (NCR) (Lugomer, 2017) and the near periphery region (NPR) of the Gaussian-like spot. The RMI/RTI in the NPR evolve from the shock and series of reshocks associated with lateral expansion and increase of the vapor density, decrease of the Atwood number and momentum transfer. Scanning electron micrographs show irregular (chaotic) web of the base-plane walls, and mushroom spikes on its nodal points with disturbed two-dimensional (2D) lattice organization. Lattice disturbance is caused by the incoherent wavy motion of background fluid due to fast reshocks, which after series of reflections change their strength and direction. Reconstruction of the disturbed lattice reveals rectangular lattice of mushroom spikes with p2mm symmetry. The splitting (bifurcation) of mushroom diameter distribution on the large and small mushroom spikes increases with radial distance from the center of Gaussian-like spot. Dynamics of their evolution is represented by the orbits or stable periods in 2D phase space. The constant mushroom diameter – stable circulation or the stable periodic orbits – are the limit cycles between the unstable spiral orbits. Those with increasing periods represent supercritical Hopf bifurcation, while those leading to decrease and disappearance represent subcritical Hopf bifurcation. The empirical models of RMI, although predict dependence of the growth rate on radial distance (distance the reshocks travel to reach the interface), show many limitations. More appropriate interpretation of the simultaneous growth and lattice organization of small and large spikes give the fundamental model based on the interference of the perturbation modes depending on their amplitude, relative phase, and the symmetry. The late-time instability in the base-plane evolves into line solitons, vortex filaments and wave–vortex structures with chaotic rather than stochastic features.

Laser-produced electron–positron pair production has been under discussion in the literature since 1969. Large numbers of positrons have been generated by lasers for a few years in studies which are also related to the studies of the physics of the fast ignitor laser fusion concept. For electron–positron pair production in vacuum due to vacuum polarization as predicted by Heisenberg (1934) with electrostatic fields, high-frequency laser fields with intensities around 1028 W/cm2 are necessary and may be available within a number of years. A similar electron acceleration by gravitation near black holes denoted as Hawking–Unruh radiation was discussed in 1985 by McDonald. The conditions are considered in view of the earlier work on pair production, change of statistics for electrons in relativistic black body radiation, and an Einstein recoil mechanism with a consequence of a physical foundation of the fine structure constant.