Publications (53)67.1 Total impact
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Article: Proton driven acceleration by intense laser pulses irradiating thin hydrogenated targets
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ABSTRACT: The Asterix iodine laser of the PALS laboratory in Prague, operating at 1315 nm fundamental frequency, 300 ps pulse duration, 600 J maximum pulse energy and 1016 W/cm2 intensity, is employed to irradiate thin hydrogenated targets placed in high vacuum. Different metallic and polymeric targets allow to generate multi-energetic and multi-specie ion beams showing peculiar properties. The plasma obtained by the laser irradiation is monitored, in terms of properties of the emitted charge particles, by using time-of-flight techniques and Thomson parabola spectrometer (TPS). A particular attention is given to the proton beam production in terms of the maximum energy, emission yield and angular distribution as a function of the laser energy, focal position (FP), target thickness and composition.Applied Surface Science 05/2013; 272:2-5. · 2.10 Impact Factor -
Article: Deuterium–deuterium nuclear reaction induced by high intensity laser pulses
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ABSTRACT: A 1016 W/cm2 Asterix laser pulse intensity, 1315 nm wavelength, 300 ps pulse duration, was employed at PALS laboratory of Prague, to irradiate thick and thin primary CD2 targets placed into the high vacuum chamber. The laser irradiation produces non-equilibrium plasma with deuterons and carbon ions emission with energy up to about 4 MeV per charge state, as measured by time-of-flight (TOF) techniques by using ion collectors and silicon carbide detectors. Accelerated deuterium ions may induce high D–D cross section for fusion processes generating 3 MeV protons and 2.5 MeV neutrons, as measured by TOF analyses. In order to increase the mono-energetic proton yield, secondary CD2 targets can be availed to be irradiated by the plasma-accelerated deuterons. Experiments demonstrated that high intensity laser pulses can be employed to promote nuclear reactions from which characteristic ion streams may be developed. Results open new scenario for applications of laser-generated plasma to the fields of ion sources and ion accelerators.Applied Surface Science 05/2013; 272:42-45. · 2.10 Impact Factor -
Article: Influence of the ablation threshold fluence on laser-driven acceleration
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ABSTRACT: Laser ablation threshold measurements has been carried out by the nanosecond-class Nd:YAG laser at LNS-INFN in Catania. Advanced targets, such as hydrogen-enriched silicon slabs and sub-micro structured polymeric samples, have been investigated. The estimated ablation fluences are correlated to recent experimental and theoretical results on high intensity laser driven ion acceleration. Characteristics of H-atoms/protons and heavier atoms/ions coming out from the bulk of the irradiated target or from surface contaminants have been determined by optical and time-of-flight spectroscopy as well as mass quadrupole spectrometry. (C) 2012 Elsevier B. V. All rights reserved.Applied Surface Science 01/2013; 272:132-137. · 2.10 Impact Factor -
Article: Laser-generated plasmas at INFN-LNS
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ABSTRACT: Hot plasmas can be generated by fast and intense laser pulses ablating solids placed in vacuum. A Nd:Yag laser operating at the fundamental and second harmonics with 9-ns pulses (maximum energy of 900 mJ) focused on metallic surfaces produces high ablation yields of the order of μg/pulse and dense plasma that expands adiabatically at supersonic velocity along the normal to the target surface. The plasma emits neutral and charged particles. Charge states up to 10+ have been measured in heavy elements ablated with intensities of the order of 1010 W/cm2. The ion temperature of the plasma is evaluated from the ion energy distributions measured with an ion energy analyzer. The electron temperature is measured through Faraday cups placed at the end of long drift tubes by using time-of-flight technique. The neutral temperature is measured with a special mass quadrupole spectrometer placed along the normal to the target surface. The plasma temperature increases with the laser pulse intensity. The ion temperature reaches values of the order of 400 eV, the electron temperature is of the order of 1 keV for hot electrons and 0.1 eV for thermal electrons, and the neutral temperature is of the order of 200 eV. The experimental apparatus, the diagnostic techniques, and the procedures for the plasma temperature characterization will be presented and discussed in detail.Plasma Physics Reports 04/2012; 32(6):514-519. · 0.65 Impact Factor -
Article: Evaluations of electric field in laser-generated pulsed plasma
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ABSTRACT: Evaluations of the electric field developed in non-equilibrium laser-generated plasma were obtained from laser ablation experiments at INFN-LNS of Catania and PALS of Prague at the regime of 1010 W/cm2 and 1016 W/cm2 intensity, respectively. Evaluations are based on the measurements of ion energy distributions from Ta plasma in vacuum obtained through an electrostatic ion energy analyser (IEA) used in both laboratories. IEA gives the energy-to-charge ratio from ion detection with time-of-flight technique. Ion energy distributions can be fitted by Coulomb-Boltzmann-shifted function which depends on the equivalent plasma temperature, plasma expansion process and Coulomb interactions. The energetic shift of the experimental distributions increases with the charge state, indicating that an equivalent voltage able to accelerate ions is developed inside the plasma. Assuming near Local Thermal Equilibrium (LTE) conditions, the voltage can be supposed developed on distances comparable with the Debye legth. Thus, from evaluations and measurements of the plasma temperature and density, it was possible to calculate the shielding length in the plasma and consequently the electrical field. Results indicate that high electric fields, of the order of tens of MV/cm or higher, can be produced inside the laser-generated plasma in the two regimes of laser intensity.Czechoslovak Journal of Physics 04/2012; 56:B580-B586. · 0.42 Impact Factor -
Article: Proton emission from thin hydrogenated targets irradiated by laser pulses at 10(16) W∕cm2.
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ABSTRACT: The iodine laser at PALS Laboratory in Prague, operating at 1315 nm fundamental harmonics and at 300 ps FWHM pulse length, is employed to irradiate thin hydrogenated targets placed in vacuum at intensities on the order of 10(16) W∕cm(2). The laser-generated plasma is investigated in terms of proton and ion emission in the forward and backward directions. The time-of-flight technique, using ion collectors and semiconductor detectors, is used to measure the ion currents and the corresponding velocities and energies. Thomson parabola spectrometer is employed to separate the contribution of the ion emission from single laser shots. A particular attention is given to the proton production in terms of the maximum energy, emission yield, and angular distribution as a function of the laser energy, focal position, target thickness, and composition. Metallic and polymeric targets allow to generate protons with large energy range and different yield, depending on the laser, target composition, and target geometry properties.The Review of scientific instruments 02/2012; 83(2):02B315. · 1.52 Impact Factor -
Article: Monoenergetic proton emission from nuclear reaction induced by high intensity laser-generated plasma.
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ABSTRACT: A 10(16) W∕cm(2) Asterix laser pulse intensity, 1315 nm at the fundamental frequency, 300 ps pulse duration, was employed at PALS laboratory of Prague, to irradiate thick and thin primary CD(2) targets placed inside a high vacuum chamber. The laser irradiation produces non-equilibrium plasma with deutons and carbon ions emission with energy of up to about 4 MeV per charge state, as measured by time-of-flight (TOF) techniques by using ion collectors and silicon carbide detectors. Accelerated deutons may induce high D-D cross section for fusion processes generating 3 MeV protons and 2.5 MeV neutrons, as measured by TOF analyses. In order to increase the mono-energetic proton yield, secondary CD(2) targets can be employed to be irradiated by the plasma-accelerated deutons. Experiments demonstrated that high intensity laser pulses can be employed to promote nuclear reactions from which characteristic ion streams may be developed. Results open new scenario for applications of laser-generated plasma to the fields of ion sources and ion accelerators.The Review of scientific instruments 02/2012; 83(2):02B111. · 1.52 Impact Factor -
Article: New methods for high current fast ion beam production by laser-driven acceleration.
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ABSTRACT: An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10(16)-10(19) W∕cm(2). The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.The Review of scientific instruments 02/2012; 83(2):02B307. · 1.52 Impact Factor -
Article: Laser-driven acceleration of protons from hydrogenated annealed silicon targets
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ABSTRACT: This paper provides the first demonstration that an hydrogenated annealed crystalline silicon may be used as a source of protons in laser-driven acceleration experiments. We analyze and compare the proton production from two silicon targets excited by a sub-nanosecond laser. One target (treated) was hydrogenated and annealed, while the other (untreated) did not undergo these procedures. The experimental results show that for the treated target, the number of generated protons is ~1.4×1015 sr−1 while for the other it is ~3.6×1013 sr−1. Their maximum energy is about 2 MeV with a laser intensity three order of magnitude lower than in previous experiments. We obtain an increase of 80% in the proton kinetic energy and of 200% in the proton current as well as a large amount of Siq+ ions (1≤q≤14) with respect to the untreated target. A deconvolution procedure based on a Boltzmann-like distribution is applied for the analysis of time-of-flight (TOF) spectra of proton and silicon ion beams.EPL (Europhysics Letters) 11/2010; 92(3):34008. · 2.17 Impact Factor -
Article: Production of dense laser-driven plasma jets using a cylindrical channel
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ABSTRACT: A simple method of production of supersonic plasma jets with parameters relevant to laboratory astrophysics applications is proposed and demonstrated. The method consists in using a cylindrical channel for guiding and collimating the plasma generated from a laser-irradiated thin foil target. In the experiment, a 120 J, 1.315 um, 0.3 ns laser pulse irradiated a thin (10 or 20 um) CH foil placed at the entrance of the cylindrical channel (made in the aluminum cylinder) of diameter dCh = 0.3 mm and length of 2 mm. It was found that when the focal spot diameter (dL) is well matched to the channel diameter (dL ≈ (2/3)dCh), the channel can form a collimated, high-density (up to 1020 cm3) plasma jet of the Mach number ≥10. The method seems to be flexible in the generation of jets of various hydrodynamic parameters and atomic numbers and does not require high-energy lasers for the jet production.Journal of Physics Conference Series 09/2010; 244(2):022023. -
Article: Effect of gold nano-particle layers on ablative acceleration of plastic foil targets
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ABSTRACT: Presence of nano-particles on target surface has been observed to lead to increased laser absorption of laser pulse in plasma. Therefore, a coating of nano-particles on foil targets could lead to an enhanced ablative acceleration. The work presented in this paper concerns this possibility. The results of experiments performed with PALS laser system (125 J, ~250 ps at 1.3 μm) with a focused intensity of about 1014 W/cm2 are presented. 15 μm thick Polyethylene teraphthalate (C10 H8 O4)n or PET foils show an almost 40% increase in target movement when coated with a layer of gold nano-particles. Comparison between targets with coating of bulk gold and nano-gold shows about 15% higher target movement in gold nano-particle coated PET targets as compared to bulk gold coating. This result is a clear indication of enhanced laser energy absorption in targets with nano-structured surface of gold. We also present evidence to show the effect of nano-particle coating on lateral thermal conduction.Journal of Physics Conference Series 09/2010; 244(2):022018. -
Article: Measurements of the highest acceleration gradient for ions produced with a long laser pulse.
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ABSTRACT: Ultrafast plasma light ion streams have been produced using the 300 ps, kJ-class iodine laser, operating at PALS Centre in Prague. Ion detection was performed through standard ion collectors (IC) in time-of-flight configuration (TOF), shielded by thin metallic absorbers. This new diagnostics technique has been theoretically studied and experimentally tested in order to cut the long photopeak contribution and to analyze the ultrafast particle signal. Processing the obtained experimental IC-TOF data, including deconvolution processes of the TOF signals, UV/soft-x-ray photopeak absorption, and ion transmission calculations for different metallic filters, is shown. Mainly amorphous carbon (graphite) targets have been irradiated in order to limit the maximum number of ion charge states and to focus our study on demonstrating the validity of the proposed investigation technique. Maximum ion energy and acceleration gradient estimations as a function of the laser energy and focal spot diameter are reported.The Review of scientific instruments 02/2010; 81(2):02A506. · 1.52 Impact Factor -
Article: Formation of a supersonic laser-driven plasma jet in a cylindrical channel
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ABSTRACT: A simple method of supersonic plasma jet production where the jet is formed in a cylindrical channel guiding the plasma generated from a laser-irradiated thin foil target is proposed and examined. High-Mach number ( ≥ 10) plasma jets of parameters relevant to laboratory astrophysics applications using 120 J, 1.315 μm, and 0.3 ns laser pulse for a thin CH foil irradiation are demonstrated. The method seems to be flexible in the production of jets of various compositions and hydrodynamic parameters and does not require high-energy lasers for the jet generation.Physics of Plasmas 11/2009; 16(11):114506-114506-4. · 2.15 Impact Factor -
Article: Single crystal silicon carbide detector of emitted ions and soft x rays from power laser-generated plasmas
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ABSTRACT: A single-crystal silicon carbide (SiC) detector was used for measurements of soft x rays, electrons, and ion emission from laser-generated plasma obtained with the use of the Prague Asterix Laser System (PALS) at intensities of the order of 10<sup>16</sup> W / cm <sup>2</sup> and pulse duration of 300 ps. Measurements were performed by varying the laser intensity and the nature of the irradiated target. The spectra obtained by using the SiC detector show not only the photopeak due to UV and soft x-ray detection, but also various peaks due to the detection of energetic charged particles. Time-of-flight technique was employed to determine the ion kinetic energy of particles emitted from the plasma and to perform a comparison between SiC and traditional ion collectors. The detector was also employed by inserting absorber films of different thickness in front of the SiC surface in order to determine, as a first approximation, the mean energy of the soft x-ray emission from the plasma.Journal of Applied Physics 07/2009; · 2.17 Impact Factor -
Article: Self-focusing effect in Au-target induced by high power pulsed laser at PALS
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ABSTRACT: Self-focusing effects, induced by ASTERIX pulsed laser at PALS Laboratory of Prague, have been investigated. Laser was employed at the third harmonics (438 nm) and intensities of the order of 1016 W/cm2. Pure Au was used as thin target and irradiated with 30° incidence angle. An ion energy analyzer was employed to detect the energy-to-mass ratio of emitted ions from plasma. Measurements were performed by changing the focal point position with a high spatial resolution step-motor. Results demonstrated that non linear processes, due to self-focusing effects, occurs when the laser beam is focused at about 200 µm in front of the target surface. In such conditions, a new ion group, having high charge state and kinetic energy, is produced because of the increment in temperature of the laser-generated plasma.Laser and Particle Beams 08/2008; 26(03):379 - 387. · 1.62 Impact Factor -
Conference Proceeding: Particular currents of ion species emitted from Fe + 2%Si plasma produced by a ND:YAG laser
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ABSTRACT: Summary form only given. In laser generated plasma experiments, the properties of ion streams such as ion energies, current densities, the ion charge state, angular and energy distributions mainly depend on the target material, the parameters of the laser radiation used and irradiation geometry. In this contribution, the influence of the ion component of the plasma has been considered in order to develop ion sources useful in laser-induced implantation and co-deposition of layers of semiconductor materials. To produce ions emitted from irradiated monocrystalline Fe + 2%Si and Fe solid targets the repetitive Nd:YAG laser with energy up to 0.8 J, in a 3.5 ns-pulse, with repetition rate of up to 10 Hz has been recently employed. The laser was operated at a first and second harmonic of fundamental frequency corresponding to wavelengths 1.06 mum and 0.53 mum, respectively. The parameters of the ion streams were measured with the use of ion collectors and an electrostatic ion energy analyzer utilizing the time-of-flight method. The analysis of the ion currents shows that the silicon in the admixture target material enhances the production of ion particles and their energy.Plasma Science, 2008. ICOPS 2008. IEEE 35th International Conference on; 07/2008 -
Article: Monocrystalline diamond detector for ionizing radiation emitted by high temperature laser-generated plasma
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ABSTRACT: A monocrystalline diamond detector was used for measurements of soft x-ray and ion emission from laser plasma obtained with the use of the PALS Asterix laser at intensities on the order of 1016 W/cm2 and pulse duration of 300 ps. Measurements were performed by varying the laser intensity and the focal position of the laser beam with respect to the target position. The spectra were obtained with the use of a diamond detector, which was without a filter, and showed not only the photopeak due to UV and soft x rays but also the ions emitted from the plasma. The detector was employed with absorbers of different thicknesses to determine, as a first approximation, the energy distribution of soft x-ray emission from the plasma. The time-of-flight technique was employed to determine the ion kinetic energies.Journal of Applied Physics 04/2008; 103(8):083106-083106-6. · 2.17 Impact Factor -
Article: Detection of energetic ions emitted from laser-produced plasma by means of CR39 solid state nuclear track detectors
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ABSTRACT: The iodine laser PALS, operated at the fundamental and third harmonic frequencies (wavelengths 1315 and 438 nm, respectively), was used to generate plasmas on various targets (Au,CF2, etc.). The investigation was performed at energies up to 400 and 250 J for 1ω and 3ω, respectively, in the 300 ps pulses. In these conditions several samples of solid state nuclear track detectors CR39 type, have been located at suitable geometrical positions to explore their capability to measure main parameters of ions emitted from the laser-produced plasmas. Track diameters and densities were observed on the uncovered detectors exposed to a lot of laser shots. Emitted ions in the energy range up to few tens of MeV, have been observed on the basis of ion collector TOF spectra. Track pattern results are shown and discussed in comparison with mentioned spectra and simulations.Radiation Effects and Defects in Solids 04/2008; 163(4-6):371-379. · 0.40 Impact Factor -
Article: Ion energy enhancement in laser-generated plasma of metallic-doped polymers
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ABSTRACT: Laser-generated plasma in vacuum are obtained ablating hydrogenated polymers at the Physics Department of Messina University and Prague Asterix Laser System laboratory of Prague. In the first case, a 3-ns, 532-nm Nd:Yag laser at 5×109 W/cm2 intensity was employed. In the second case, a 300-ps, 438-nm iodine laser at 5×1014 W/cm2 intensity was employed. Different ion collectors are used in time-of-flight configuration to monitor ‘on line’ the ejected ions from the plasma at different angles with respect to the normal direction to the target surface. Measurements demonstrated that the mean ion velocity, directed orthogonally to the target, increases for ablation of polymers doped with metallic elements (Br, Cu, Au and W) with respect to that obtained with no-doped polymers. The possible mechanism explaining the results can be found in the different electron density of the plasma, due to the higher number of electrons coming from the metallic doping elements. This charge enhancement increases the equivalent ion voltage acceleration, i.e. the electric field generated in the non-equilibrium plasma placed in front of the ablated target surface.Radiation Effects and Defects in Solids 04/2008; 163(4-6):339-347. · 0.40 Impact Factor -
Article: Studies of craters’ dimension for long-pulse laser ablation of metal targets at various experimental conditions
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ABSTRACT: Long pulse laser shots of the PALS iodine laser in Prague have been used to obtain metal target ablation at various experimental conditions. Attention is paid mainly to the dependencies of the crater diameter on the position of minimum laser-focus spot with regard to the target surface, by using different laser wavelengths and laser energies. Not only a single one, but two minima, independently of the wavelength, of the target irradiation angle and of the target material, were recorded. Significant asymmetries, ascribed to the non-linear effects of intense laser beam with pre-formed plasma, were found, too. Estimations of ejected mass per laser pulse are reported and used to calculate the efficiency of laser-driven loading. Results on metal target ablation and crater formation at high intensities (from 2 × 1013 to 3 × 1016 W/cm2) are presented and compared. Crater depth, crater diameter and etching yield are reported versus the laser energy, in order to evaluate the ablation threshold fluence.Applied Surface Science 02/2008; 254(9):2797–2803. · 2.10 Impact Factor
Top co-authors
Top Journals
Institutions
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2012
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INFN - Istituto Nazionale di Fisica Nucleare
Legnaro, Veneto, Italy
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2006–2012
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Università degli Studi di Messina
- Dipartimento di Fisica e di Scienze della Terra
Messina, Sicily, Italy
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2005–2012
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Institute of Physics ASCR
Praha, Hlavni mesto Praha, Czech Republic
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1994–2012
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Academy of Sciences of the Czech Republic
- • Fyzikální ústav
- • Ústav fyziky plazmatu
Praha, Hlavni mesto Praha, Czech Republic
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