Experimental studies of generation of ~100 MeV Au-ions from the laser-produced plasma

AbstractUsing the PALS iodine laser system, Au ions with the charge state up to 58+ and with the kinetic energy as high as ~300 MeV were generated. The production of these ions was tested in dependence on the laser frequency (1ω, 3ω), on the irradiation/detection angles (0°, 30°), on the focus position with regard to the target surface, and on the target thickness (500 µm, 200 µm, 80 µm). A larger amount of the fastest ions was produced with 1ω than with 3ω, the most of the fast ions were recorded in the direction ~10°from the target normal, the optimum focus position is in front of the target and should be set on with a precision of 50 µm. The forward emission is weaker than the backward one for both of the thinner targets (which burn through) at our experimental conditions

Factors influencing parameters of laser ion sources

Various applications demand various kinds of ions. Charge state, energy and the amount of laser produced ions depend, primary, on the wavelength, the energy, the pulse duration, and the focusing ability of the laser used. Angle of the target irradiation, angle of the ion extraction (recording), and mainly the focus setting may significantly influence especially the portion of ions with the highest charge states. The participation of non-linear processes on the generation of ions with extremely high parameters is demonstrated. The observed effects support the idea of a longitudinal structure of the self-focused laser beam with a space period of ∼200 µm

The influence of an intense laser beam interaction with preformed plasma on the characteristics of emitted ion streams

AbstractIntense laser-beam interactions with preformed plasma, preceding the laser-target interactions, significantly influence both the ion and X-ray generation. It is due to the laser pulse (its total length, the shape of the front edge, its background, the contrast, the radial homogeneity) as well as plasma (density, temperature) properties. Generation of the super fast (FF) ion groups is connected with a presence of non-linear processes. Saturated maximum of the charge states (independently on the laser intensity) is ascribed to the constant limit radius of the self-focused laser beam. Its longitudinal structure is considered as a possible explanation for the course of some experimental dependencies obtained

X-ray microscopy of living multicellular organisms with the Prague Asterix Iodine Laser System

Soft X-ray contact microscopy (SXCM) experiments have been performed using the Prague Asterix Iodine Laser System (PALS). Laser wavelength and pulse duration were λ = 1.314 μm and τ (FWHM) = 450 ps, respectively. Pulsed X rays were generated using teflon, gold, and molybdenum targets with laser intensities I ≥ 1014 W/cm2. Experiments have been performed on the nematodes Caenorhabditis elegans. Images were recorded on PMMA photo resists and analyzed using an atomic force microscope operating in contact mode. Our preliminary results indicate the suitability of the SXCM for multicellular specimens

Shock pressure induced by 0.44 [mu]m laser radiation on aluminum targets

Shock pressure generated in aluminum targets due to the interaction of 0.44 μm (3 ω of iodine laser) laser radiation has been studied. The laser intensity profile was smoothed using phase zone plates. Aluminum step targets were irradiated at an intensity I ≈ 1014 W/cm2. Shock velocity in the aluminum target was estimated by detecting the shock luminosity from the target rear using a streak camera to infer the shock pressure. Experimental results show a good agreement with the theoretical model based on the delocalized laser absorption approximation. In the present report, we explicitly discuss the importance of target thickness on the shock pressure scaling

Generation of Secondary Particles from Subnanosecond Laser Irradiation of Targets at Intensities of 10^16 W/cm^-2

none15J.Krasa; D.Margarone; D.Klir; A.Velyhan; A.Picciotto; E.Krousky; K.Jungwirth; J. Skala; M.Pfeifer; J. Ullschmied; J.Kravarik; K.Rezac; P.Kubes; P.Parys; and L.RycJ., Krasa; D., Margarone; D., Klir; A., Velyhan; Picciotto, Antonino; E., Krousky; K., Jungwirth; J., Skala; M., Pfeifer; J., Ullschmied; J., Kravarik; K., Rezac; P., Kubes; P., Parys; L., Ry

Effectiveness of ICD therapy in real clinical practice. The Olomouc ICD Registry

Background. Clinical parameters linked to a low benefit of ICD implantation and increased mortality risks are needed for an individualized assessment of potential benefits and risks of ICD implantation. Methods. Analysis of a prospective registry of all patients hospitalized from 2009 to 2019 in a single centre for a first implantation of any type of ICD. Results. A total of 2,681 patients were included in the registry. Until the end of follow-up (38.4 ± 29.1 months), 682 (25.4%) patients died. The one-year mortality in all patients, the one-year CV mortality, the three-year mortality in all patients, and the three-year CV mortality were 7.8%, 5.7%, 20.6%, and 14.8%, respectively. There was a statistically significant difference when the subgroups were compared according to the type of cardiomyopathy. No significant difference was found between primary and secondary prevention and between the types of devices. Male gender, age ≥ 75 years, diabetes mellitus, and atrial fibrillation were associated with a significantly increased mortality risk. Conclusion. In an analysis of a long-term follow-up of 2,681 ICD patients, we found no mortality difference between patients with ischemic or non-ischemic cardiomyopathy and in the device type. A higher mortality risk was found in men, patients older than 75 years, diabetics, and those with atrial fibrillation

Shock dynamics and shock collision in foam layered targets

Abstract We present an experimental study of the dynamics of shocks generated by the interaction of a double-spot laser in different kinds of targets: simple aluminum foils and foam–aluminum layered targets. The experiment was performed using the Prague PALS iodine laser working at 0.44 μm wavelength and irradiance of a few 1015 W/cm2. Shock breakouts for pure Al and for foam-Al targets have been recorded using time-resolved self-emission diagnostics. Experimental results have been compared with numerical simulations. The shocks originating from two spots move forward and expand radially in the targets, finally colliding in the intermediate region and producing a very strong increase in pressure. This is particularly clear for the case of foam layered targets, where we also observed a delay of shock breakout and a spatial redistribution of the pressure. The influence of the foam layer doped with high-Z (Au) nanoparticles on the shock dynamics was also studied

Skin depth plasma front interaction mechanism with prepulse suppression to avoid relativistic self-focusing for high-gain laser fusion

Measurements of the ion emission from targets irradiated with neodymium glass and iodine lasers were analyzed and a very significant anomaly observed. The fastest ions with high charge number Z, which usually are of megaelectron volt energy following the relativistic self-focusing and nonlinear-force acceleration theory, were reduced to less than 50 times lower energies when 1.2 ps laser pulses of about 1 J were incident. We clarify this discrepancy by the model of skin depth plasma front interaction in contrast to the relativistic self-focusing with filament generation. This was indicated also from the unique fact that the ion number was independent of the laser intensity. The skin layer theory prescribes prepulse control and lower (near relativistic threshold) laser intensities for nonlinear-force-driven plasma blocks for high-gain ignition similar to light ion beam fusion