This survey is devoted to a few basic atomic problems associated with the stopping of nonrelativistic pointlike ions in dense and hot matter, and also to the Stark broadening diagnostics of the resulting beam-produced plasmas.

First, we consider the free electron contribution, taken in the RPA approximation with an exact dynamic dielectric function, valid at any temperature. Therefore, we obtain stopping power and straggling for any projectile velocity. The temperature dependence is of special relevance for a projectile energy smaller than 5 MeV/a.m.u.

Next, we revise the Barkas effect (Z3 corrections) through a novel and compact formulation, which is based on an analogy with electron impact broadening theory. It facilitates inclusion of the non hydrogenic and electronic structure of the target ions, in a more selective way. The results may increase the usual Z2-stopping by 15 to 30 per cent corrections.

Then, we show how the Stark broadening diagnostics of the compressed D + T fuel, seeded with high Z species, arising from the surrounding envelopes, may provide accurate determination of the electron number density ne. In this connection, it should be appreciated that the relatively long compression times (≃ 20 nsec) suggested by the HIBALL numerical simulation allow for a nearly Local Thermodynamic Equilibrium (LTE) state in the target, with Te ≃ Ti. As a consequence, spectroscopic measurements are expected to be easier to implement in HIF targets, than in laser ones.

A tentative proposal for the use of Stark broadening diagnostics of inflight excited and highly stripped ion projectiles is displayed in § 5.

Experiments involving an HIB produced by a standard accelerator, and interacting with an independently produced coronal plasma are finally outlined.

The generation of harmonics in two-frequency undulator in a self-amplified spontaneous emission free electron laser (SASE FEL) is studied in order to produce Roentgen radiation in a relatively compact sized installation. The dynamics of SASE FEL is analyzed with the help of the phenomenological model to obtain the maximum of the X-ray high-harmonic power. The model accounts for the properties of the undulator magnetic field and of the electron beam and includes the major sources of losses, such as the electron energy spread, etc. It is compared and calibrated with the existing data on a FEL experiment. The advantages of the two-frequency undulator for Roentgen SASE FEL are demonstrated and the possibility to generate powerful mild Roentgen radiation at already ~25 m length is shown. The evolution of the bunching coefficients for high harmonics is studied together with the evolution of the FEL-induced energy spread. The linear and non-linear regimes are explored for common and for two-frequency undulators The usage of the two-frequency undulator for cascade SASE FEL with high X-ray harmonic power and high-harmonic bunching coefficients with low-induced energy spread is proposed.

Laser-generated plasma is obtained in high vacuum (10−7 mbar) by irradiation of metallic targets (Al, Cu, Ta) with laser beam with intensities of the order of 1010 W/cm2. An Nd:Yag laser operating at 1064 nm wavelength, 9 ns pulse width, and 500 mJ maximum pulse energy is used. Time of flight measurements of ion emission along the direction normal to the target surface were performed with an ion collector. Measurements with and without a 0.1 Tesla magnetic field, directed along the normal to the target surface, have been taken for different target-detector distances and for increasing laser pulse intensity. Results have demonstrated that the magnetic field configuration creates an electron trap in front of the target surface along the axial direction. Electric fields inside the trap induce ion acceleration; the presence of electron bundles not only focuses the ion beam but also increases its energy, mean charge state and current. The explanation of this phenomenon can be found in the electric field modification inside the non-equilibrium plasma because of an electron bunching that increases the number of electron-ion interactions. The magnetic field, in fact, modifies the electric field due to the charge separation between the clouds of fast electrons, many of which remain trapped in the magnetic hole, and slow ions, ejected from the ablated target; moreover it increases the number of electron-ion interactions producing higher charge states.

Inertial fusion energy (IFE) research indicates that the energy generation by means of cryogenic fuel target compression requires that targets must be injected to the target chamber center at a rate of about 6 Hz. This requirement can be fulfilled only if the targets are free-standing. The most interesting results concerning the activity of the Lebedev Physical Institute in the area of free-standing targets (FST) fabrication, characterization and delivery are presented.

Progress in heavy ion target design over the past few years has focused on relaxing the target requirements for the driver and for target fabrication. We have designed a plastic (CH) ablator capsule that is easier to fabricate and fill than the beryllium ablator we previously used. In addition, two-dimensional Rayleigh–Taylor instability calculations indicate that this capsule can tolerate ablator surface finishes up to 10 times rougher than the NIF specification. We have also explored the trade-off between surface roughness and yield as a method for finding the optimum capsule. We have also designed two new hohlraums: a “hybrid” target and a large-angle, distributed radiator target. The hybrid target allows a beam spot radius of almost 5 mm while giving gain of 55 from 6.7 MJ of beam energy in integrated Lasnex calculations. To achieve the required symmetry with the large beam spot, internal shields were used in the target to control the P2 and P4 asymmetry. The large-angle, distributed radiator target is a variation on the distributed radiator target that allows large beam entrance angles (up to 24°). Integrated calculations have produced 340 MJ from 6.2 MJ of beam energy in a design that is not quite optimal, In addition, we have done a simple scaling to understand the peak ion beam power required to compress fuel for fast ignition using a short pulse laser.

An important component of the U.S. effort to achieve thermonuclear ignition in 2010 on the National Ignition Facility is the development of high quality 2 mm diameter spherical capsules to function as the ablator and contain the cryogenic DT fuel. Three ignition capsule designs have been developed, and detailed fabrication specifications for each design have been established and placed under change control. A research program with activities coordinated mainly between Lawrence Livermore, General Atomics and Los Alamos is underway to demonstrate fabrication of capsules meeting specifications. The point design for ignition campaigns beginning in 2010 is a Cu-doped Be capsule that has a radial gradient in Cu dopant level in the capsule wall. This capsule is being produced by sputter deposition of Be and Cu onto either a hollow glow discharge polymer (GDP) spherical mandrel or a solid spherical mandrel, followed by removal of the mandrel and polishing of the capsule. A key goal in the U.S. is to demonstrate fabrication of this capsule by the end of 2006. Two other ignition capsule designs are also being developed as contingencies to the point design. One contingency design is a GDP capsule that has a radial Ge dopant level in its wall. This capsule is produced by co-deposition of Ge and GDP onto a PAMS mandrel followed by thermal removal of the mandrel. The second contingency design is a uniform Cu-doped Be capsule that is fabricated from high purity fine grain Be0.3at.%Cu alloy using a precision machining route followed by polishing. Ignition targets to be fielded in 2010 will be filled with DT fuel through a small fill hole. Laser drilling capability has been developed and used to drill approximately 5 μm diameter holes through capsule walls for DT filling. Characterization methods necessary for characterizing capsules are being developed.

Second-harmonic generation of the relativistic self-focused chirped laser pulse in plasma has been studied with the exponential plasma density ramp profile in the presence of a planar magnetostatic wiggler. It is evident that the exponential plasma density ramp is helpful in enhancing second-harmonic generation as, with the introduction of the exponential plasma density ramp, self-focusing becomes stronger and hence, it leads to enhance the harmonic generation of the second order in the plasma. Also, it is observed that the efficiency of second-harmonic generation enhances significantly with an increase in the value of the chirp parameter. Further, the magnetostatic wiggler helps in enhancing the harmonic generation of the second order. This is due to the fact that dynamics of the oscillating electrons is altered due to the Lorentz force which, in turn, modifies the plasma wave and, hence, results in the efficient second-harmonic generation.

The realization of an ideal volume compression of laser-irradiated fusion pellets (by C. Yamanaka) opens the possibility for an alternative to spark ignition proposed for many years for inertial confinement fusion. A re-evaluation of the difficulties of the central spark ignition of laser driven pellets is given. The alternative volume compression theory, together with volume burn and volume ignition (discovered in 1977), have received less attention and are re-evaluated in view of the experimental verification by Yamanaka, generalized fusion gain formulas, and the variation of optimum temperatures derived at self-ignition. Reactor-level DT fusion with MJ-laser pulses and volume compression to 50 times the solid-state density are estimated. Dynamic electric fields and double layers at the surface and in the interior of plasmas result in new phenomena for the acceleration of thermal electrons to suprathermal electrons. Double layers also cause a surface tension which stabilizes against surface wave effects and Rayleigh–Taylor instabilities.

The Compton scattering of a terawatt-class, femtosecond laser pulse by a high-brightness, relativistic electron beam has been demonstrated as a viable approach toward compact, tunable sources of bright, femtosecond, hard X-ray flashes. The main focus of this article is a detailed description of such a novel X-ray source, namely the PLEIADES (Picosecond Laser–Electron Inter-Action for the Dynamical Evaluation of Structures) facility at Lawrence Livermore National Laboratory. PLEIADES has produced first light at 70 keV, thus enabling critical applications, such as advanced backlighting for the National Ignition Facility and in situ time-resolved studies of high-Z materials. To date, the electron beam has been focused down to σx = σy = 27 μm rms, at 57 MeV, with 266 pC of charge, a relative energy spread of 0.2%, a normalized horizontal emittance of 3.5 mm·mrad, a normalized vertical emittance of 11 mm·mrad, and a duration of 3 ps rms. The compressed laser pulse energy at focus is 480 mJ, the pulse duration 54 fs Intensity Full Width at Half-Maximum (IFWHM), and the 1/e2 radius 36 μm. Initial X rays produced by head-on collisions between the laser and electron beams at a repetition rate of 10 Hz were captured with a cooled CCD using a CsI scintillator; the peak photon energy was approximately 78 keV, and the observed angular distribution was found to agree very well with three-dimensional codes. The current X-ray dose is 3 × 106 photons per pulse, and the inferred peak brightness exceeds 1015 photons/(mm2 × mrad2 × s × 0.1% bandwidth). Spectral measurements using calibrated foils of variable thickness are consistent with theory. Measurements of the X-ray dose as a function of the delay between the laser and electron beams show a 24-ps full width at half maximum (FWHM) window, as predicted by theory, in contrast with a measured timing jitter of 1.2 ps, which contributes to the stability of the source. In addition, K-edge radiographs of a Ta foil obtained at different electron beam energies clearly demonstrate the γ2-tunability of the source and show very good agreement with the theoretical divergence-angle dependence of the X-ray spectrum. Finally, electron bunch shortening experiments using velocity compression have also been performed and durations as short as 300 fs rms have been observed using coherent transition radiation; the corresponding inferred peak X-ray flux approaches 1019 photons/s.

A method for developing invariant equations of state (EOS) for which solutions of the Noh problem will exist is developed. The ideal gas EOS is shown to be a special case of the general method. Explicit solutions of the Noh problem in planar, cylindrical, and spherical geometry are determined for a Mie–Gruneisen and the stiff gas equation of state.

We investigate the stopping power of heavy ions in strongly coupled electron plasmas by performing molecular dynamics (MD) computer simulations. A comparison with conventional weak coupling theories shows that these fail in describing the stopping power at low ion velocities and strong coupling. Then nonlinear screening effects become important and this causes a change in the dependence of the stopping power on the ion charge Zp at low ion velocities. From the MD simulation, we find the stopping power to behave like ZP1.43 instead of the weak coupling behavior Zp2 ln(const/Zp). Similar results were recently obtained by experiments in connection with electron cooling at heavy ion storage rings.

We analyze the undulator radiation from planar bi-harmonic undulators with account for all principle losses in real devices. The exact analytical expressions for the UR spectrum, intensity, and the line shape are obtained in terms of special functions. The interplay of various broadening contribution is elucidated and their role is explored. Suspension and boost of certain harmonics by fine tuning the undulator parameters is demonstrated. The constant non-periodic magnetic constituents are studied to compensate the divergency of the electronic beam. The examples of harmonic generation in various undulator schemes with single and double period magnetic field are explored. Influence of inhomogeneous and homogeneous broadening on these harmonics is demonstrated. The analysis is applied to evaluate the harmonics in self-amplified spontaneous emission free electron laser.

In this paper, we suggest the creation of a nanoparticles and nanotubes by using the interaction of a femtosecond laser with a solid target in a vacuum. A simple model is used to predict the optimal target and the laser parameters for the production of efficient nanoparticles. At the Soreq laboratory, experiments are performed with aluminium and carbon targets using a femtosecond laser. The irradiated targets are composed of either a thin layer of aluminium or of carbon, deposited on a transparent heat-insulating glass substrate. The nanoparticle debris is collected on a silicone wafer for X-ray diffraction (XRD), for scanning electron microscopy (SEM), and for atomic force microscopy (AFM). For transmission electron microscopy (TEM), the debris is caught on a copper grid covered on one side with a carbon membrane. Our experiments confirm the creation of crystal nanoparticles for aluminium and nanotubes for carbon experiments.

Propagation of an intense laser pulse in plasma with a periodically modulated density is considered using envelope equations. The laser induces modifications of the plasma refractive index via relativistic and ponderomotive nonlinearities. In the region of high plasma density, the self focusing effect of nonlinearity suppresses the diffraction divergence, and the laser converges. As the beam enters into the low density region, the diffraction tends to diverge it offsetting the convergence due to the curvature it has acquired. For a given set of plasma parameters, there is a critical power of the laser above which it propagates in a periodically focused manner. Below this power the laser undergoes overall divergence. At substantially higher powers, the laser beam continues to converge until the saturation effect of nonlinearity suppresses the self focusing and diffraction predominates. The effect of density ripple is to cause overall increase in the self focusing length. The minimum spot size decreases with the wave number of the ripple.

A space-resolved charge density of ions is derived from a time-resolved current of ions emitted from laser-produced plasma and expanded into the vacuum along collision-free and field-free paths. This derivation is based on a similarity relationship for ion currents with “frozen” charges observed at different distances from the target. This relationship makes it possible to determine a map of ion charge density at selected times after the laser plasma interaction from signals of time-of-flight detectors positioned at a certain distance from the target around a target-surface normal. In this work, we present maps of the charge density of ions emitted from Cu and polyethylene plasmas. The mapping demonstrates that bursts of ions are emitted at various ejection angles ϕn with respect to the target-surface normal. There are two basic directions ϕ1 and ϕ2, one belonging to the fastest ions, i.e., protons and carbon ions, and the other one to the slowest ions being a part of each plasma plume.

This paper is devoted to investigations of laser energy transfer into solid targets with respect to the focusing lens focal point position relative to the solid target surface as obtained at the PALS laser facility. The third harmonic of the PALS laser beam with energy ~90 J and pulse duration ~250 ps (FWHM) was used for irradiation of two kinds of targets made of Cu: a slab and a 3.6 µm thick foil. The focal point of the beam was located either inside or in front of the target surface, and care was taken to ensure the same laser spot radii in both cases (250 µm). It was demonstrated that these two opposite focal point positions give rise to significantly different laser-plasma interactions: with either depression or maximum of the laser intensity distribution in the center of the beam, respectively. It was also verified that the focal point position inside of the target is favorable for plasma jets creation, whereas the opposite case is more effective for acceleration of flyers.

The temporal and spatial X-ray emission from PPG-X, an X-pinch driven by pulsed power generator, was studied by using diamond photo-conducting detectors and pinhole cameras. It was found that the X-ray pulse usually consists of two sub-nanosecond peaks with a time interval of about 0.5 ns, these two X-ray peaks are consistent with two point sources of X-ray recorded with pinhole camera. The total X-ray energy changes from shot to shot and is averaged to be 0.35 J for hν > 1.5 keV. The size of the X-ray point source is in the range from 100 µm to 5 µm, decreasing rapidly with the increase of the photon energy. The X-pinch was used as X-ray source for backlighting the electrical explosion of single wire and for phase-contrast imaging of a mosquito.

This paper is a part of a series intended to develop a detailed understanding of the physics of hydrogen thyratrons. This theory is needed, because the improvement of electrical switches such as the thyratron are now necessary for the development of high power lasers and other devices. In this paper, a detailed analysis of many different electron, atomic and molecular collisional and radiative processes is made, in order to determine the electron temperature in a thyratron plasma. Calculations of the rates for production of Balmer lines are made and the results are summarized in a way that can be used for in situ measurements.

The effects of multiple pulses of a CO2 laser with energy of 2.5 J and pulse duration of 200 ns on the surface morphology of ion irradiated CR-39 is investigated in light of the modification in its track registration properties. For this purpose, a CR-39 was exposed by a CO2 laser generated hydrogen, argon, cadmium, air molecular ions (N2 and O2, etc.), high energy (300 KeV) proton beam from Cock Croft Walton accelerator, and α (5 MeV) from 0.5 μCi Pu239 source. The registered tracks were enlarged after 6 h of 6.25 N NaOH etching. These etched detectors were then exposed to different number of CO2 laser shots. The etched detectors were then analyzed by a computer controlled optical microscope (Lexica DMR series). It was observed that even a single shot of CO2 laser, irrespective of the registered ions tracks, can change the track registration properties of CR-39, and can remove the vaporization resistant skin present on the polymer (CR-39). A significant change in track density and track shaping regardless of the ions is observed. At the outside of the focal area, the ion density of different registered tracks is compared graphically before and after laser irradiation. Laser ablation of unexposed CR-39 is also done with multiple pulses CO2 laser. In this regard, the coherent and non-coherent structures, diffraction patterns, circular fringes with corrugations and ripples, droplets, chain like structures with cluster formation, chain folded crystallites, and hole drilling were observed. The irradiation induced ablation of the polymer is of great importance in electronics industry, lithography, etc.

We describe the role for the next-generation “superlasers” in the study of matter under extremely high-energy-density conditions in comparison with previous uses of nuclear explosives for this purpose. As examples, we focus on three important areas of physics that have unresolved issues that must be addressed by experiment: equations of state, hydrodynamic instabilities, and the transport of radiation. We describe some of the advantages the large lasers will have in a comprehensive, laboratory-based experimental program.