It is cylindrical converters that are generally considered for the purpose of changing the ion beam energy into X rays, with their irradiation to be provided through the cylinder end. This article studies a target having a disk-shaped converter to be irradiated sideways. It may be practical when one fails to overcome difficulties with the focusing of ion beams into a spot of a diameter smaller than a few millimeters.

We study strongly correlated plasmas far from equilibrium with the ultimate aim of describing the cooling of heavy ion beams by electrons. With the help of molecular dynamics (MD) computer simulations, we conclude that the relaxation of a two-component plasma depends strongly upon the preparation of the initial configuration. If the initial data have no intercomponent correlations, such will build up during the evolution so that the intercomponent potential energy decreases while the kinetic energy increases. These effects become more pronounced for strongly coupled plasmas and limit the efficiency of electron cooling. We cannot confirm certain mean-field predictions on the influence of an external magnetic field on the cooling process. A study of the relaxation of anisotropic velocity distributions for a one-component plasma shows deviations from meanfield results for strongly coupled plasmas.

Free electron lasers (FELs) place very stringent requirements on the quality of electron beams. Present techniques for commissioning and operating electron accelerators may not be optimized to produce the high brightness beams needed. Therefore, it is proposed to minimize the beamline errors in electron accelerator transport systems by minimizing the deviations between the experimentally measured and design transport matrices of each beamline section. The transport matrix for each section is measured using evoked responses. In addition, the transverse phase space of the beam is reconstructed by measuring the spatial distribution of the electrons at a number of different betatron phases and applying tomographic techniques developed for medical imaging.

The Second International Conference on the Frontiers of Plasma Physics and Technology was held in Goa, India, from February 21–25, 2005. This conference explored a number of fundamental and applied plasma physics topics. Special attention was focused on the exploration of frontiers in physics and technology of high energy density plasmas—a topic growing at a very fast pace due to the emergence of extremely powerful laser sources. Reviews on activities and new opportunities for large laser facilities in prominent laboratories of Asia, Europe, and Canada were presented. Talks on recent advances on laser driven Wakefield particle acceleration scheme were very exciting. This technology has a strong potential of revolutionizing the existing accelerator physics, technology, and radiation sources such as synchrotrons and X-ray free-electron lasers. Discussions were also given on the generation of extreme physical conditions similar to those existing in astrophysical objects, under laboratory conditions using intense lasers. This technique may lead to an easy and inexpensive way to simulate and understand a variety of astrophysical phenomena. This aspect of realization of astrophysical conditions in a laboratory has now become reality, and soon may lead to routine experiments. New applications of laser in the designs of light-crafts may soon become reliable.

In order to establish a compact all-optical Thomson scattering source, experimental studies were conducted on the 45 TW Ti: sapphire laser facility. By including a steel wafer, mixed gas, and plasma mirror into a double-exit jet, several mechanisms, such as shock-assisted ionization injection, ionization injection, and driving laser reflection, were integrated into one source. So, the source of complexity was remarkably reduced. Electron bunches with central energy fluctuating from 90 to 160 MeV can be produced. Plasma mirrors were used to reflect the driving laser. The scattering of the reflected laser on the electron bunches led to the generation of X-ray photons. Through comparing the X-ray spots under different experimental conditions, it is confirmed that the X-ray photons are generated by Thomson scattering. For further application, the energy spectra and source size of the Thomson scattering source were measured. The unfolded spectrum contains a large amount of low-energy photons besides a peak near 67 keV. Through importing the electron energy spectrum into the Monte Carlo simulation code, the different contributions of the photons with small and large emitting angles can be used to explain the origin of the unfolded spectrum. The maximum photon energy extended to about 500 keV. The total photon production was 107/pulse. The FWHM source size was about 12 μm.

The characteristics of a laser plasma created by a high intensity UV excimer laser were investigated. The UV laser plasma was used as a switch for control of the laser pulse duration for the first time. An X-ray preionized XeCl laser pulse duration can be changed from 10 to 85 ns. This technique is useful for many applications of excimer lasers requiring various pulse durations.

1-D computer simulations have been performed to study the influence of X-rays preheating on the compression of spherical laser-produced plasmas. The targets are glass microballoons filled with Neon at the initial pressure 10 bars. It is assumed that the only significant absorption process in the Neon is by inverse bremsstrahlung absorption. The results indicate that the radiative preheating energy has a nonnegligible effect on the compression, and a study of the Lawson criterion shows that this effect is more important for high-Z target shell materials and for thicker shells.

Surface periodic structures are generated upon irradiation of a silicon carbide (SiC) thin film by the plasma produced by 40 fs pulses from a Ti:Sapphire laser focused onto a thick low density polyethylene (LDPE) foil facing the SiC film. Independently of the number of laser pulses applied, these structures, with average regular periodicity of 710 nm, are evident throughout all irradiated areas. We attribute their formation to the efficient coupling of the unfocused femtosecond laser pulse with the incoherent extreme ultraviolet component of the laser-generated LDPE plasma.

As the development of the pulsed power technology, high voltage pulse transformer (HVPT) is usually used instead of Marx generator as a charging device for the pulse forming line (PFL) of intense electron-beam accelerator (IEBA), and which make the IEBA compact. However, during the operation of the IEBA, the HVPT may be destroyed for the failure of electrical insulation and the over-voltage. So in this paper, the output voltage characteristics of IEBA, characteristics of the voltage at the output terminal of HVPT at four kinds of load conditions are analyzed, including load matching, load short, load open, and surface flashover in the vacuum chamber. It is found that load short, load open, and surface flashover in vacuum chamber will affect the voltage at the output terminal of HVPT, and an oscillation wave could be formed, which affect the electrical insulation of HVPT and decrease the lifetime of HVPT. Meanwhile, the waveform of the load voltage is also modified, especially at the conditions of load open and surface flashover in vacuum chamber. When the load is open, the amplitude of the output main pulse of IEBA is twice the charging voltage of BPFL. However, the amplitude of the output pulse of IEBA is modified by the voltage at the output terminal of HVPT, and the resistance of main switch channel has a great effect on the amplitude of the load voltage. When surface flashover occurs in the vacuum chamber, the pulse duration of the output voltage will be decreased. So, during the operation of IEBA, load short, load open and surface flashover in vacuum chamber should be avoided.

Experimental results are reported on an extractor for pulsed, high-intensity beams of intermediate mass ions. Aluminum and indium plasmas were generated using a metal vapor vacuum arc. A method for electrostatic separation of ions from electrons at the anode was utilized to generate constant current beams, insensitive to plasma flux variations.

A maximum extraction voltage of 30 kV was applied across a 1·6 cm gap. Voltage pulse length ranged from 10 to 50μsec. Peak current densities of 15 mA/cm2 and normalized emittance of εn<3χ10-7; π-m-rad were achieved for Al+ and In+ from a 20-cm2 anode. Ions were predominantly in the +1 ionization state with no observable species contamination. The technology may have application to the induction linac approach to Accelerator Inertial Fusion.

The mass ablation rate and ablation pressure on laser-irradiated spherical microshells were measured using the space-resolved X-ray spectroscopy. A new method for the study of the ablation by means of the Doppler shifted X-ray images is proposed. The time-resolved measurements of X-ray emission from layered microtargets allow us to determine the heat front penetration through the microshell wall.

Intense light-ion beams are being developed for investigations of inertial confinement fusion (ICF). This effort has concentrated on developing the Particle Beam Fusion Accelerator II (PBFA II) at Sandia as a driver for ICF target experiments, on design concepts for a high-yield, high-gain Laboratory Microfusion Facility (LMF), and on a comprehensive system study of a light-ion beam-driven commercial fusion reactor (LIBRA). This article reports on the status of design concepts and research in these areas.

The linear conversion theory of laser produced plasma filaments is studied in this paper. By calculations for the energy flux of the second harmonic emission on the basis of the planar wave-plasma interaction model, it has been found that there exists no 2ω0 harmonic emission in the direction perpendicular to the incident laser, in contradiction with the experiments. Therefore, we have proposed a linear conversion theory on the second harmonic emission from a plasma filament and discovered the intense 2ω0 harmonic emission in the direction perpendicular to the incident laser, which is in agreement with the experiments.

The two-dimensional snake scanning of the CCD method provides an effective solution to measure small-scale light spots which are smaller than one CCD pixel. The influences of the A/D conversion digits and response uniformity of the CCD on the measurement error are studied. When the A/D conversion digit is 20, the measurement error can be ignored. The maximum error value of the nonuniform response of the CCD pixel when the order of the super-Gaussian function is 10 is 0.7 μm. The research results can be used to guide the experiment.

The main point of the hydrodynamic model of the electromagnetic field (Deng Ximing & Fang Honglie 1979, 1980) is that the motion of the electromagnetic field can be divided into two parts: orbital motion and intrinsic motion. This paper defines an intrinsic angular momentum deduced from the intrinsic motion and a related Î (imaginary number) operator, whose basic properties are discussed. In addition, the conservation property of the intrinsic angular momentum and the relation between it and the spin angular momentum of the electromagnetic field are described.

We study the setting up of relativistic ponderomotive non-linearity in an under-dense collisionless cold plasma. Using the fluid model, coupled system of equations of the laser beam and electron plasma oscillations has been derived. We present the numerical simulation for this coupled system of equations, when the coupling arises through relativistic ponderomotive non-linearity. The filamentation of the laser beam has been found to vary appreciably with perturbation wave number. The results show that with time, localized structures become more complex and the plasma oscillation frequency spectra have several harmonic peaks at terahertz frequencies when the electron plasma frequency is in terahertz range and laser frequency is around 2.35 × 1015 rad/s. We also present the semi-analytical model to capture the underlying physics.

The Rayleigh—Taylor instability is studied by means of a slab model and when slab thickness D is comparable to the ablation-to-critical surface distance. Under these conditions the perturbations originating at the ablation front reach the critical surface, and in order to determine the instability growth rate, we must impose boundary conditions at the corona. Stabilization occurs for perturbation wave numbers such that kD ˜ 10.

We investigate an ionization injection scheme in a “weakly” non-linear regime of a wakefield, driven by sub-TW, few-cycle laser pulses in a single-stage, high-Z gas. This medium simultaneously provides the background wake fluid electrons from its lower ionization states and the necessary dephased electrons from its higher ionization states. Two dimensional-particle-in-cell simulations show the generation of relativistic electron beamlets having up to 15 MeV peak energy, with a narrow energy-spread and sub-fs duration. Since the currently-available sub-TW, few-cycle laser systems operate at kHz repetition rates, the presented scheme is capable of producing kHz attosecond electron bunches and their associated radiations which can find unique applications, for instance, in attosecond diffraction and microscopy.

We study the effect of magnetic field in an implosion process achieved by radiation. A time-varying sinusoidal magnetic field is seen to affect the continuous transition of space-like detonation to time-like detonation at the core of implosion region. The oscillating varying magnetic field has a significant effect in increasing the volume of the time-like detonation of the core of implosion and also modifies the time of the implosion process. This transition can have significant outcome both theoretically and experimentally in the areas of high-energy hadronization of quark–gluon plasma matter and inertial confinement fusion efforts of fuels.