The irradiation of cylindrical targets by intense heavy ion beams was studied using a two-dimensional numerical simulation code including radiation effects on the hydrodynamical flow. Solid and hollow Aluminum targets as well as gas tubes are studied for various beam configurations with a view to identifying the characteristic features of the flow and possible observables, especially the emitted radiation from Xenon gas tubes.

To accelerate high-intensity heavy-ion beams to high energy in the booster ring (BRing) at the High-Intensity Heavy-Ion Accelerator Facility (HIAF) project, we take the typical reference particle 238U35+, which can be accelerated from an injection energy of 17 MeV/u to the maximal extraction energy of 830 MeV/u, as an example to study the basic processes of longitudinal beam dynamics, including beam capture, acceleration, and bunch merging. The voltage amplitude, the synchronous phase, and the frequency program of the RF system during the operational cycle were given, and the beam properties such as bunch length, momentum spread, longitudinal beam emittance, and beam loss were derived, firstly. Then, the beam properties under different voltage amplitude and synchronous phase errors were also studied, and the results were compared with the cases without any errors. Next, the beam properties with the injection energy fluctuation were also studied. The tolerances of the RF errors and injection energy fluctuation were dictated based on the CISP simulations. Finally, the effect of space charge at the low injection energy with different beam intensities on longitudinal emittance and beam loss was evaluated.

This paper deals with the analysis of growth rate of modulation instability of a laser pulse propagating in a clustered gas. Finite pulse effects are considered to be a perturbation. Growth rates of modulation instability for 100 fs and 80 fs at the centroid as well as at the front and back of the pulses are evaluated and graphically analyzed. It has been shown that with decrease in pulse duration the growth rate of modulation instability increases at the front, back as well as at the centroid of the pulse. It is also shown that the change in growth rate of modulation instability at the front as well as at the back of the pulse in comparison to the centroid of the pulse for 80 fs pulse is less in comparison to that of 100 fs pulse.

Utilizing an ultraintense (1016 W cm−2) fs laser, the laser/matter interaction of the tetrahedral CH3I molecule is investigated. A mass spectrum and the angular distributions of fragment ions arising from Coulomb explosion of molecular ions, obtained with linearly polarized light, are presented. The distributions for In+ (n ≤ 7), CHm+ (m ≤ 3), Cp+ (p ≤ 4) and H+ ions are all anisotropic and maximal when the polarization lies along the spectrometer axis. The molecule hence seems to behave as a diatomic, with the fragment ions being ejected along the field direction. Also presented are mass spectra of the isomers 1- and 2-nitropropane, which are explosive species, taken for horizontal and vertical polarizations at both 375 and 750 nm. It is shown that femtosecond laser mass spectrometry (FLMS) can be used to distinguish between these two isomers through their differing dissociation patterns. Isomer identification is important for many different applications and FLMS may provide a means of achieving this for a wide range of molecules.

Nitrogen lasers have been used for many years to make dye solutions lase. A nitrogen laser, which transverse electrical discharge in gas at atmospheric pressure has been built in our laboratory. It has been characterized and applied to pump different dyes: Rhodamine 6G, Coumarin 440, DOTCI, and pyranine in simple “on axis” geometric configuration. It has been shown that pyranine can lase in the absence of any optical external mirror cavity, this happens at very low threshold, and in different solvents. Dyes under consideration can be grouped into two major classes according to their lasing behavior independently on their concentration in the solvent: Rhodamine 6G and DOTCI can lase both axially or transversally and Coumarin 440 and pyranine can lase only axially. Other intriguing features have been observed that span from simultaneous multiple beam generation, to super fluorescence and to distribute axial pumping of dye solutions. A preliminary basis for understanding and controlling such processes is the spatial energy distribution and the energy density of the beam.

The stopping power of dense nonideal plasmas is calculated in different approximations. The T-matrix approximation for binary collisions is compared with the random phase approximation (RPA) approximation for dielectric fluctuations. Within a microscopic model, the dynamical evolution of the velocity of the projectile is calculated. It reproduces well experimental values for the stopping of fast heavy ions. Further improvements due to correlations are discussed. Both concepts, cluster decomposition and memory, are compared and it is found that they lead to the same quantum virial corrections of the Beth-Uhlenbeck type in equilibrium. However, memory in the kinetic equation causes an additional renormalization of the effective energy transfer in nonequilibrium.

The beam dynamics design of the low energy DTL section of a fusion driver linac based on the IH-structure is presented. The acceleration of a 209Bi1+ beam by an IH-DTL operated at 27 MHz (54 MHz) is investigated for two specific injection energies at 60 A keV and at 200 A keV, respectively. Both cases are optimized separately, with the goal to find out the maximum achievable acceleration gradient, beam current, as well as the most attractive field strength range of the quadrupole lenses. Calculations are performed on one beamlet, but the results can be applied to build up multibeam cavities. H-mode cavities are very well suited for this purpose and provide high acceleration efficiency, especially at low particle velocity. In addition, the “Combined 0° structure” (“Kombinierte Null Grad Struktur–KONUS”) beam dynamics concept allows grouping into modular units consisting of short, simple rf cavities and of multiaperture quadrupole triplet lenses located in the intertank sections.

Recent direct drive implosion experiments, performed on the OMEGA laser, have been analyzed by comparing full two-dimensional (2D) and one-dimensional (1D) numerical simulations. The 2D simulations result in a fusion yield higher than experimental results. A simple full-mixing model, leaving only the clean region, overestimates yield degradation. Fully turbulent mixing is expected to develop in most of the mixing region; however regions slightly beyond the radius of the most penetrating spike are expected to remain clean and to contribute to fusion yield. One can correct the mixing model by redefining the clean region. Accounting for this unmixed region results in improved agreement with experimental results. Differences in central pressure, density, temperature, and fusion rate in implosions dominated by low mode number perturbations imply that mix effects might not be limited to the mix region, and that 2D simulations are necessary to describe the large scale flow affecting the central region. The same analysis has been undertaken for implosions with different convergence ratios, but with similar initial perturbation spectra. These implosions should be compared to implosions dominated by high mode number perturbations, which might be described by models based on 1D simulations.

A scheme of generating ultra-intense attosecond pulses in ultra-relativistic laser interaction with under-dense plasmas is proposed. The attosecond pulse emission is caused by an oscillating transverse current sheet formed by an electron density spike composed of trapped electrons in the laser wakefield and the residual transverse momentum of electrons left behind the laser pulse when its front is strongly modulated. As soon as the attosecond pulse emerges, it tends to feed back to further enhance the transverse electron momentum and the transverse current. Consequently, the attosecond pulse is enhanced and developed into a few cycles later until the density spike is depleted out due to the pump laser depletion. To control the formation of the transverse current sheet, a non-uniform plasma slab with an up-ramp density profile in front of a uniform region is adopted, which enables one to obtain attosecond pulses with higher amplitudes than that in a uniform plasma slab.

The physics of the formation of cryogenic fuel layers with various internal structures has been studied in regard to the development of promising layering techniques for modern inertial confinement fusion (ICF) experiments. The investigations have been made with inertial confinement fusion target (ICF targets) and in a target modeling system (TMS) with the nonisochoric process of cryogenic layer formation. The results indicate that the solidlayer structure in TMS differs essentially from that obtained in ICF targets. The thermal history of a fuel layer at separation into the condensed and vapor phases is found to depend upon whether the initial gas density is more, less, or equal to the critical value for a given fuel material. The issue on the fuel-layer fabrication in the form of a long-living quasiamorphous layer is considered. A new low-temperature method to homogenize a polycrystalline cryogenic layer has been proposed and examined. The operational temperature was 4.2 K. The time to achieve the complete homogeneity of solid hydrogen was 150 s. No limitation, with respect to the thickness of a cryogenic layer, was found. The critical target is suggested as a new type of an ICF target.

A scheme for the improvement of proton beam quality by the optimized dragging field from the interaction of ultraintense laser pulse with a complex double-layer target is proposed and demonstrated by one-dimensional particle-in-cell (Opic1D) simulations. The complex double-layer target consists of an overdense proton thin foil followed by a mixed hydrocarbon (CH) underdense plasma. Because of the existence of carbon ions, the dragging field in the mixed CH underdense plasma becomes stronger and flatter in the location of the proton beam than that in a pure hydrogen (H) underdense plasma. The optimized dragging field can keep trapping and accelerating protons in the mixed CH underdense target to high quality. Consequently, the energy spread of the proton beam in the mixed CH underdense plasma can be greatly reduced down to 2.6% and average energy of protons can reach to 9 GeV with circularly polarized lasers at intensities 2.74 × 1022 W/cm2.

Laser beat wave heating of magnetized plasma via electron cyclotron damping is proposed and analyzed. A plasma density ripple is presumed to exist across the magnetic field. Two collinear lasers propagating along the magnetic field exert a beat frequency ponderomotive force on electrons, driving a large amplitude Bernstein quasi-mode which suffers cyclotron damping on electrons. Finite Larmor radius effects play an important role in the heating. Electron temperature initially rises linearly with time. As the temperature rises cyclotron damping becomes stronger and temperature rises rapidly. The process, however, requires ripple wavelength shorter than the wavelength of the beat wave.

KrF and other short wavelength lasers are ideal candidates for producing hot dense plasmas since the laser energy can be absorbed with high efficiency by classical mechanisms, thereby virtually eliminating anomalous absorption and the production of non-thermal electrons. A high power KrF laser system employing optical beam multiplexing and stimulated Brillouin scattering to produce pulses as short as 1 ns and focused intensities on target of 1011−1014 W/cm2 has been developed for producing such plasmas and studying laser/plasma interaction phenomena. A variety of studies on absorption, transport, ablation, X-ray conversion and stimulated scattering instabilities have been pursued with this ¼ μm laser on single atomic number and multi-layer targets. This paper briefly describes some of the features of the KrF laser system and highlights some of the characteristics of the hot dense plasmas produced.

Bifurcation phenomenon in the energy-angular correlation spectrum of the vacuum laser acceleration has been observed with computer simulation. Concerning a focused laser pulse, the classical single-valued energy-angular correlation spectrum for a plane wave is, besides broadened to a band, bifurcated with the classical value in between the two branches. Analytic expression to describe the correlation has been derived and physical explanations based on the ponderomotive potential model and Lorentz-Newton force analyses are presented. The theoretical results are supported by numerical simulations which have been compared with the experimental results. This study is helpful in designing vacuum laser acceleration experiments.

A model for the hydrodynamics of a layer-structured target impinged by an intense ion beam is presented. For some power law time pulses, the flow in the absorber region, which is entirely different from that in the tamper, becomes self-similar for planar geometries. Scaling laws for the ablation pressure and the implosion velocity have been obtained from the analysis.

A novel method to generate shock waves in small tubes is demonstrated. A femtosecond laser is applied to generate an optical breakdown an aluminum film as target. Due to the sudden appearance of this non-equilibrium state of the target, a shock wave is induced. The shock wave is further driven by the expanding high-pressure plasma (up to 10 Mbar), which serves as a quasi-piston, until the plasma recombines. The shock wave then propagates further into a glass capillary (different square capillaries with hydraulic diameter D down to 50 µm are applied). Shock wave propagation is investigated by laser interferometry. Although the plasma is an unsteady driver, due to the geometrical confinement of the capillaries, rather strong micro shocks can still propagate as far as 35 times D. In addition to the experiments, the initial conditions of this novel method are investigated by hydrocode simulations using MULTI-fs.

In this work, we present experimental results on the behavior of liquid water at megabar pressure. The experiment was performed using the HIPER (High-Intensity Plasma Experimental Research) laser facility, a uniaxial irradiation chamber of GEKKO XII (GXII) at the Institute of Laser Engineering (ILE), and the PHELIX at GSI (GSI Helmholtz Centre for Heavy Ion Research), a single-beam high-power laser facility, to launch a planar shock into solid multilayered water samples. Equation-of-state data of water (H2O are obtained in the pressure range 0.50–4.6 Mbar by tuning the laser-drive parameters. The Hugoniot parameters (pressure, density, etc.) and the shock temperature were simultaneously determined by using VISAR and SOP as diagnostic tools and quartz as the standard material for impedance mismatch experiments. Finally, our experimental results are compared with hydrodynamic simulations tested with different equations of state, showing good compatibility with tabulated SESAME tables for water.

The single ionization and dissociation of ethanol molecules induced by low-energy electrons (E0 = 90 eV) are investigated using multiparticle coincident momentum spectroscopy. By detecting two outgoing electrons (e1 and e2) and one fragment ion in coincidence, we obtain the energy deposition (E0 − E1 − E2) during electron ionization of the molecule, i.e., the binding energy spectra, for production of the different ionic fragments C2H5OH+, C2H4OH+, COH+, and H3O+. These data allow us to study the ionization channels for different ionic products. In particular, we focus on H3O+ as a product of double hydrogen migration. It is found that this channel mainly originates from the ionization of outer-valance orbitals (3a″,10a′, 2a″, 9a′, 8a′, 1a″, and 7a′). Additionally, there are minor contributions from the inner-valence orbitals such as 6a′, 5a′, and 4a′. Quantum chemistry calculations show two fragmentation pathways: concerted and sequential processes for formation of H3O+.

Analytical study of the linear stability of one-dimensional double layers in nonmagnetized plasmas based on the solution of the Vlasov–Poisson system is presented. Electromagnetic effects are not included. A self-consistent equilibrium electrostatic potential Φ0(z) that monotonically increases from a low level at z = − ∞ to a high level at z = + ∞ is assumed. We model this potential as a piecewise continuous function of z and we assume that Φ0(z) has constant values for − ∞ z ≤ 0 and L ≤ z < ∞, L being the thickness of the double layer. The BGK states for the Vlasov–Poisson system provide an explicit expression for the velocity distribution of the reflected electrons required for the particular double layer configuration. The stability of the double layers is studied via the linearized Vlasov and Poisson equations using the WKB approximation.