Laser produced planar mini flyer generation has widely gained importance owing to its wide ranging applications in the field of condensed matter, astrophysics, material research, shock phenomenon, etc. Flattop smooth laser beam profile as driver is the primary requirement for planar flyer generation besides special multilayered target geometry. We present here laser produced thin metallic planar mini-flyer generation using a fiber optic plate (FOP) of 8 mm thickness and about 6 µm fiber dimension. This technique is unique in the sense that it doesn't require large length as compared to optical fiber. A Gaussian shape laser beam from a laser oscillator was allowed to fall on the FOP generating a speckle pattern. This pattern was relayed and amplified using lenses and laser amplifiers to achieve energy of about 400 mJ. The beam was focused on a substrate (fused silica) based multilayered target on which flyer disks of different materials such as Al. Cu, Br, and Ta were attached. Velocities as high as 400 m/s was measured for Al flyer of 1.5 mm diameter and thickness 50 µm. Flyer disks were completely recovered after the laser shot. We also present a theoretical analysis along with experimental results of the laser beam smoothing technique using a He-Ne laser and FOP. Each channel of the FOP acts as a small single mode optical fiber. The basic idea was to divide the incoming coherent beam into many beam-lets introducing random distribution in length or/and diameter of optical fibers of FOP. The individual FOP channel acts as a diverging source because of single mode fiber with natural divergence λ/d. However, due to the small randomness in length or diameter, the individual diffraction sources are not in phase. This results in the generation of speckles in both near (Fresnel) and far field (Fraunhoffer) destroys the spatial coherence of the beam.

The dense Z-pinch project at Imperial College is aimed at achieving radiative collapse to high density in a hydrogen plasma, and also to study plasmas close to controlled fusion conditions. To this end, the MAGPIE generator (2.4 MV, 1.25, and 200 ns) has been built and tested, and is now giving preliminary experimental data at 60% of full voltage for carbon and CD2 fibers. These discharges are characterized by an initial radial expansion followed by the occurrence of m = 0 structures with transient X-ray emission from bright spots. Late in the discharge a disruption can occur, accompanied by hard X-ray emission from the anode due to an energetic electron beam and, in the case of CD2 fibers, a neutron burst. Concomitant theoretical studies have solved the linear stability problem for a Z-pinch with large ion Larmor radii, showing that a reduction in growth rate of m = 0 and m = 1 modes to about 20% of the magnetohydrodynamic (MHD) value can occur for a parabolic density profile when the Larmor radius is optimally 20% of the pinch radius. Two dimensional MHD simulations of Z-pinches in two extremes of focussed short-pulse laserplasma interactions and of galactic jets reveal a nonlinear stabilizing effect in the presence of sheared flow. One-dimensional simulations show that at low line density the lower hybrid drift instability can lead to coronal radial expansion of a Z-pinch plasma.

Three triode extraction systems are simulated by IBSimu ion optical code for Amirkabir Helicon Ion Source (AHIS). The optimized pierce and suggested parabolic electrodes are introduced for the first time in this paper. The obtained N+ beam for parabolic geometry designed for ion implantation has 66 keV energy, and 10.4 mA current. Ion beam emittance and Twiss parameters of the emittance ellipse as the function of x term index are calculated for parabolic electrode equation. The simulated triode extraction systems have been evaluated by using of optimized parameters such as the extraction voltage, gap distance, plasma electrode (PE) aperture, and ion temperature. The extraction voltage, gap distance, PE aperture, and ion temperature have been changed in the range of 58–70 kV, 35–39 mm, 4–6 mm, and 0.5–4.4 eV in the simulations, respectively.

The time and wavelength dependencies of luminescence resulted from 11 low-lying Cd II levels in He-Cd medium excited by 252Cf fission fragments have been measured in the temperature range from 553 to 669 K and various buffer gas pressures (1.5–5 atm). The method used is based upon applying multichannel coincidence technique and single-photon spectrometry. The lifetime, pumping rate, and luminescence spectral line width data obtained for 325- and 441.6-nm transitions have been used to estimate lasing characteristics of He-Cd medium under optimal conditions.

Graphene micrometric particles have been embedded into polyethylene at different concentrations by using chemical–physical processes. The synthesized material was characterized in terms of mechanical and optical properties, and Raman spectroscopy. Obtained targets were irradiated by using a Nd:YAG laser at intensities of the order of 1010 W/cm2 to generate non-equilibrium plasma expanding in vacuum. The laser–matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon and proton ion beams from laser-generated plasma are presented and discussed.

When an extremely high pressure gas is irradiated by an intense laser light, a dense plasma produced at the focal spot moves towards the focusing lens with a high velocity. Making use of this phenomenon, a new plasma-bridged gap switch is proposed and its switching characteristics is experimentally examined. From the experiments, it is confirmed that the switching time is almost constant with the applied voltage only when the focal spot is just on the positive electrode, indicating that the bridging of gap is caused by the laser light.

The simplified perturbation method of Vandenboomgaerde et al. (2002) is applied to both the Richtmyer–Meshkov and the Rayleigh–Taylor instabilities. This theory is devoted to the calculus of the growth rate of the perturbation of the interface in the weakly nonlinear stage. In the standard approach, expansions appear to be series in time. We build accurate approximations by retaining only the terms with the highest power in time. This simplifies and accelerates the solution. High order expressions are then easily reachable. For the Richtmyer–Meshkov instability, multimode configurations become tractable and the selection mode process can be studied. Inferences for the intermediate nonlinear regime are also proposed. In particular, a class of homothetic configurations is inferred; its validity is verified with numerical simulations even as vortex structures appear at the interface. This kind of method can also be used for the Rayleigh–Taylor instability. Some examples are presented.

Terahertz (THz) radiation from a plasma cylinder with embedded radial electric and axial magnetic fields is investigated. The plasma density and the electric and magnetic fields are such that the electron plasma frequency is near the electron cyclotron frequency and in the THz regime. Two-dimensional particle-in-cell simulations show that the plasma electrons oscillate not only in the azimuthal direction but also in the radial direction. Spectral analysis shows that the resulting oscillating current pattern has a clearly defined characteristic frequency near the electron cyclotron frequency, suggesting resonance between the cyclotron and plasma oscillations. The resulting far-field THz radiation in the axial direction is also discussed.

The results of the experiments at the installation “PICO,” with thin foils heating by laser radiation pulses of nanosecond duration are reported. The Al foils with thickness in the range from 3 μ up to 40 μ were used as targets. The flux density was varied from 1013 W/cm2 to 1014 W/cm2. The sharp dependence of the portion of laser energy that passed through the target on foil thickness was observed. This phenomena was accompanied by a relatively small decrease of the passed radiation pulse duration. The anomalously high speed burning through of thin foil was observed in these experiments and the conclusion on the possible mechanism of this phenomena has been done on the base of comparison of experimental data with theoretical calculations. The observed phenomena can be interpreted with a conjecture about the local burning through of a target, in the small areas of the target surface, with many more values of flux density than the average one following laser radiation self-focusing and formation of “hot spots.”

The effect of thermal flux transport inhibition on the coupling of the spherical dense pellet core with the hot electron halo produced at the plasma resonance layer has been investigated. The analytic expressions for the core-corona coupling and the optimum temperature of the overlapping region (at which this coupling is maximum) have been derived as a function of ‘flux limit’ parameter and the laser wavelength. Relevant calculations indicate that the core-corona coupling is sensitive to the mean electron temperature and the scaling of its maximum value with the laser wavelength remains absolutely unaffected by plasma ablation. The subsequent results on laser wavelength scaling are compared and contrasted with the predictions of other investigations. The heat transfer from the hot electron cloud to the dense core can be increased by an order of magnitude in case of the uninhibited flux.

Multiple ionization of large clusters when they are irradiated by an intense ultrashort laser pulse is investigated. Different mechanisms, responsible for cluster ionization, are investigated. It is found that the ionization of large clusters, irradiated by a strong intense ultrashort laser pulse, is realized by means of the surface thermoemission.

The transport of relativistic electron beam in compressed cylindrical targets was studied from a numerical and experimental point of view. In the experiment, cylindrical targets were imploded using the Gekko XII laser facility of the Institute of Laser Engineering. Then the fast electron beam was created by shooting the LFEX laser beam. The penetration of fast electrons was studied by observing Kα emission from tracer layers in the target.

Hot-spot path in the thermodynamic space $({\rm \rho} R,T_{\rm i} )_{{\rm hs}} $ is investigated for direct-drive scaled-target family covering a huge interval of kinetic energy on both sides of kinetic threshold for ignition. Different peak implosion velocities and two initial aspect ratios have been considered. It is shown that hot spot follows almost the same path during deceleration up to stagnation whatever the target is. As attended, after stagnation, a clear distinction is done between non-, marginally-, or fully igniting targets. For the last, ionic temperature can reach very high values when the thermonuclear energy becomes very high.

In this paper, the ion jet generation from the interaction of an ultraintense laser pulse and a rear-side concave target is investigated analytically using a simple fluid model. We find that the ion expanding surface at the rear-side is distorted due to a strong charge-separation field, and that this distortion becomes dramatic with a singular cusp shown on the central axis at a critical time. The variation of the transverse ion velocity and the relative ion density diverge on the cusp, signaling the emergence of an on-axis ion jet. We have obtained analytical expressions for the critical time and the maximum velocity of the ion jet, and suggested an optimum shape for generating a collimated energetic ion jet. The above theoretical analysis has been verified by particle-in-cell (PIC) numerical simulations.

The Hartree-Fock theory of fluctuations leading to simple formulae for configuration probabilities is used in a Detailed Configuration Accounting calculation of opacity in the case of an iron plasma. A direct Detailed Term Accounting method is also applied. The correlations of subshell occupation numbers, which are accounted for in the HF theory, show small effect on the theoretical spectrum corresponding to conditions of a recent measurement.

In fast ignition of inertial confinement fusion, hot electron beam is considered to be an appropriate energy source for ignition. However, hot electrons are divergent as they are transporting in over-dense plasma. So collimating the hot electrons becomes one of the most important issues in fast ignition. A method to collimate hot electron beam by external magnetic field is proposed in this paper. The external field can be generated by compressing a seed magnetic field at the stage of laser-driven implosion. This method is confirmed by particle-in-cell simulations. The results show that hot electrons are well collimated by external magnetic field from magnetic-flux compression.

In this work, two laser-produced plasma (LPP) sources – extreme ultraviolet (EUV) and a LPP soft X-ray (SXR) source were used to create Ne photoionized plasmas. A radiation beam was focused onto a gas stream, injected into a vacuum chamber synchronously with the radiation pulse. EUV radiation spanned a wide spectral range with pronounced maximum centered at λ≈11 nm, while in case of the SXR source spectral maximum was at λ≈1.4 nm. Emission spectra of photoionized plasmas created this way were measured in a wide spectral range λ = 10–100 nm. The dominating spectral lines originated from singly charged ions (Ne II) and neutral atoms (Ne I). For the highest radiation fluence, spectral lines originating from Ne III and even Ne IV species were detected. Differences between the experimental spectra, obtained for all irradiation conditions, were analyzed. They were attributed either to different fluence or spectral distribution of driving photons.

Ionization distributions and radiation spectra of a dense plasma driven by intense ion beams are studied by solving stationary rate equations. Expressions for the rate coefficients are derived. Optically thin plasmas of hydrogen and carbon are considered neglecting hydrodynamic motion. Results on level populations versus temperature, on power balance and equilibrium states, and also on emission spectra are given. In particular, the transition from beam-determined plasma states to thermal equilibrium states is discussed. Beam parameters are chosen close to those in experiments now being planned.

We present a novel waveform synthesized by a half-cycle fundamental wave (800 nm) and a half-cycle subharmonic wave (2400 nm) with an appropriate carrier-envelope phase and a phase delay, in which more ionized electrons can recombine with its parent ions to emit high-order harmonic, giving rise to both the extension of the extreme ultraviolet supercontinuum and the enhancement of harmonic conversion efficiency. An isolated attosecond pulse with considerable energy is obtained as well. By performing time-frequency analyses, it is revealed that the prolonged opposite electric field increases the recombining probability of high-energy electrons.

A review of work done on laser generated shocks in solids using a high-peak-power Nd:glass laser in the Laser and Plasma Technology Division of the Bhabha Atomic Research Centre is presented in this paper. The 20-J/5-ns Nd:glass laser used in the experiments is able to produce focused laser intensities in the range of 5 × 1011-1013 W/cm2 and a shock pressure in the range of 0.1–5 Mbar. A l-J/100-ps Nd:glass laser is also being developed for laser shock studies, details of which are presented. Several diagnostics have been developed for laser shock studies of which the main diagnostics are optical shadowgraphy, optical interferometry, and laser velocity interferometry for particle velocity measurement. The measurement of ablation pressure in various types of targets, the scaling of ablation pressure with laser intensity, the effect of laser beam nonuniformity on shockfront or ablation pressure uniformity, the smoothing of shockfront and pressure profiles in high-Z coated and high-Z doped targets, and so on, are the various experimental studies conducted. We have tried to study X-ray driven ablation in aluminum and plastic targets using gold and copper as X-ray producing targets. Uniform pressure of about 0.1 Mbar has been generated over an area of 4 mm2