Publications (37)40.87 Total impact
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Article: Experimental studies of interaction of intense long laser pulse with a laser-created Ta plasma
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ABSTRACT: Characteristics of ions, emitted from the laser produced plasma, were systematically investigated using high power iodine laser system PALS, operating at 3ω. A Ta target was irradiated perpendicularly with laser pulse energy 150 J. Changing the laser focus position, not only the laser intensity, but also the length (duration) of laser beam interaction with pre-formed plasma is changing. Self-focusing of laser beam in self-created plasma was proved, moreover with longitudinal structure with a period of ∼ 200 µm.Czechoslovak Journal of Physics 04/2012; 56:B506-B514. · 0.42 Impact Factor -
Article: Studies of the laser-created craters produced on solid surfaces at various experimental conditions
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ABSTRACT: Results on target ablation and crater formation at low and high laser intensities (at 5 × 109 W/cm2 with Nd:YAG laser in Catania and 3 × 1016 W/cm2 with iodine laser PALS in Prague) are compared. Attention is paid mainly to the crater formation (crater diameter) in dependence on the position of minimum laser-focus spot (maximum laser intensity) with regards to the target surface, at various laser wavelengths and laser energies. Significant asymmetries of these dependencies were found, similarly, as it was reported earlier e.g. for maximum charge-state of ions and X-ray radiations. Surprisingly not a single one, but two minima were observed, independently of the wavelength, the angle of the target irradiation and the target material.Czechoslovak Journal of Physics 04/2012; 56:B542-B549. · 0.42 Impact Factor -
Article: Experimental studies of emission of highly charged Au-ions and of X-rays from the laser-produced plasma at high laser intensities
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ABSTRACT: Au ions with maximum charge states 58+ and with the kinetic energy in a region of ∼100 MeV were recorded. The influence of various experimental conditions is presented and discussed.The European Physical Journal D 04/2012; 54(2):487-492. · 1.48 Impact Factor -
Article: Laser induced direct implantation of ions
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ABSTRACT: Results on iodine laser production of Ag, Au, Pb, Sn and Ta ions are presented and experiments on their implantation into steel, Al and plastics are compared and discussed. Ions were implanted without additional acceleration into metals to the depth of several hundreds of nanometers, and into plastics to a depths of up to several micrometers.Czechoslovak Journal of Physics 04/2012; 50:81-90. · 0.42 Impact Factor -
Article: Interferometric investigation of an early stage of plasma expansion with the high-power laser system PALS
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ABSTRACT: The results of interferometric investigation of early stage of plasma expansion carried out in the high-power laser system PALS are presented. The plasma was generated on planar solid Al and Mo targets, irradiated by iodine laser pulses with energies of 100 and 600 J in 0.4 ns at a wavelength of 1.315 µm. The interferometric investigation allowed to determine electron density distributions at chosen moments of the plasma expansion. On the basis of these distributions, information about dynamics and properties of expanding plasma was obtained. The effects of laser-target interaction, i.e., the diameter and the depth of craters as well as the crater shape, were investigated.Czechoslovak Journal of Physics 04/2012; 52(3):395-404. · 0.42 Impact Factor -
Article: Analysis of processes participating during intense iodine-laser-beam interactions with laser-produced plasmas
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ABSTRACT: The high-power iodine laser PALS was used to generate highly charged Ta ions and to study non-linear processes in laser-produced plasma. Longitudinal structures of the expanding plasma, obtained by using an X-ray streak camera on a time scale 2 ns, are presented. Various bright spots (moon-like, half-moon-like), expansion-path curvature and even their splitting were recorded. These phenomena are ascribed to the effect of the magnetic field that is self-generated at high laser intensities.Radiation Effects and Defects in Solids 09/2010; 165(6-10):463-471. · 0.40 Impact Factor -
Article: Application of a single-crystal CVD diamond detector for simultaneous measurement of ions and X-rays from laser plasmas
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ABSTRACT: A single-crystal chemical vapor deposition (CVD) diamond detector (DD) of a sandwich structure was used for the measurement of soft X-rays and ions emitted from plasmas obtained with the use the PALS laser system in Prague. The detector was fabricated in the Institute of Nuclear Physics PAN in Cracow with the use of diamond material obtained from Element Six, Inc. In the laser experiment, the responses of the detector to X-rays and ions were compared with the responses of an ion collector (IC). The signals from the DD proved to be much different to the ones from the IC, which is explained by different mechanisms of producing current in both detectors. Due to its high sensitivity, the DD is useful for the measurement of fast protons. Both detectors can be used for simultaneous measurement of soft X-rays and ions from the same laser shot and the data obtained are complementary.Radiation Effects & Defects in Solids: Incorporating Plasma Science & Plasma Technology. 06/2010; 165(6-10):481-487. -
Article: Ion emission from laser ablation of Cu and Cu98/Be2 alloy targets
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ABSTRACT: The properties of pulse laser ablation of Cu and Cu98/Be2 materials are studied, and the differences in the emission of Cu ions are emphasized. The iodine high-power laser system PALS in Prague and a KrF laser were used to perform the experiments at the fundamental harmonics λ 0 = 1.315 μm and λ 0 = 248 nm delivering energy up to 500 J and 600 mJ, respectively. Pure Cu and Cu98/Be2 alloy targets of 50, 500 and 1000 μm thickness were ablated to measure the influence of the Be admixture on the emission of Cu ions. The alloy Cu98/Be2 was chosen due to the well-defined amount of a beryllium admixture in the plasma in contrast to the incidental amount of carbon, oxygen and hydrogen impurities chemisorbed on target surfaces. It was approved that the emission of Cu ions driven by the KrF laser exhibits a higher gain from the Cu98/Be2 plasma in contrast to the Cu plasma. The ion emission induced by laser intensities near the threshold of fast ion generation is significantly affected by the emission of ionized impurities chemisorbed on a target surface and by repetitive outbursts of fast ions if generated. Under these conditions, the influence of the 2% Be admixture on the emission of Cu ions plays only a minor role.Radiation Effects & Defects in Solids: Incorporating Plasma Science & Plasma Technology. 06/2010; 165(6-10):488-494. -
Article: Generation of high currents of carbon ions with the use of subnanosecond near-infrared laser pulses.
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ABSTRACT: Emission of carbon currents reaching values up to 2 A/cm(2) at a distance of 1 m from the laser ion source driven by the subnanosecond Prague Asterix Laser System operated at a fundamental wavelength of 1315 nm is reported. Graphite targets were exposed to intensities up to 5x10(16) W/cm(2) varying both the laser energy and the position of the laser beam focus with respect to the target surface. The maximum energy gain of carbon ions was approximately = 1 MeV/u. At high laser intensities the shape of time-of-flight spectra is also formed by plasma outbursts, whose growth correlates with the oscillatory self-focusing of the laser beam.The Review of scientific instruments 02/2010; 81(2):02A504. · 1.52 Impact Factor -
Article: Laser generation of Au ions with charge states above 50+.
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ABSTRACT: Results of recent studies on highly charged Au ion generation, using the intense long pulses of the PALS high power iodine laser (lambda=1.315 microm, E(L)=800 J400 ps), operating under variable experimental conditions (1omega, 3omega, varying target thickness and changing focus positions), are presented. Both the ion collectors and the ion electrostatic analyzers were applied for the identification of ions in a large distance from the target. The time-of-flight collector signals were treated by a means of peak deconvolution assuming a shifted Maxwell-Boltzmann form of the constituent ion current peaks. Attention was paid to the influence of pulse precursor, which becomes evident, especially, if using thinner targets and 1omega. The results for 3omega point to the presence of several groups of ions with the highest recorded charge state Au(53+).Review of Scientific Instruments 03/2008; 79(2 Pt 2):02C715. · 1.37 Impact Factor -
Article: Factors influencing parameters of laser ion sources
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ABSTRACT: 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 [similar]200 µm.Laser and Particle Beams 05/2007; 25(02):199 - 205. · 1.62 Impact Factor -
Article: Charge-energy distribution of Ta ions from plasmas produced by 1ω and 3ω frequencies of a high-power iodine laser
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ABSTRACT: The high-power iodine laser system PALS (λ0 = 1.315 μm at the fundamental laser frequency, 1ω, and λ1/3 = 0.438 μm at the third harmonic frequency, 3ω), with a maximum laser intensity IL of up to about 3×1016 W/cm2, was used to generate highly charged Ta ions. Maximum ion charge states slightly above z = 50+ were determined by using an electrostatic ion energy analyzer and the maximum energy of emitted ions, estimated from the ion collector signals, was even higher than Ei = 22 MeV, as determined by track detectors. Charge-state distributions, as well as charge-energy distributions were evaluated for both 1ω and 3ω laser frequencies. The focus position with regard to the target surface (in addition to the focus spot size) determines not only the laser power density deposited and the amount of produced ions, but it also directly influences the mechanisms of ion generation. Highly charged ions with the charge states above 50+ can be generated either by using a sufficiently high laser intensity (about 1×1016 W/cm2) or, at lower laser intensities (IL>2×1014 W/cm2), in the case where the conditions for the relativistic self-focusing are met. © 2004 American Institute of Physics.Review of Scientific Instruments 05/2004; 75(5):1588-1591. · 1.37 Impact Factor -
Article: Skin depth plasma front interaction mechanism with prepulse suppression to avoid relativistic self-focusing for high-gain laser fusion
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ABSTRACT: 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.Laser and Particle Beams 02/2004; 22(01):83 - 87. · 1.62 Impact Factor -
Article: The use of silicon photodiodes for x-ray diagnostics in the PALS plasma experiments
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ABSTRACT: Silicon photodiodes of different types were tested for the possibility of measurement of high-intensity x-ray pulses from the plasmas produced by the 1 kJ PALS laser system in Prague. The x-ray energy range of the operation of the detectors was 1–20 keV. The tests were done with the use of different targets at the laser energy up to 740 J in the case of fundamental frequency (1ω, 1315 nm) and up to 230 J in the case of the 3rd harmonics (3ω). The detectors that were assigned for the measurement of the harder part of the spectrum (5–20 keV) can operate without overloading at all laser energies used, but the detectors for soft radiation can be easily overloaded above 200 J (at the fundamental frequency). Some problems with noise compatibility were encountered, as well. The possible improvements of detection systems for the future experiments are proposed. The detectors investigated in the experiment can be applied for finding the optimal condition for producing the hottest plasmas and for a precise calibration of the target positioning system.Plasma Physics and Controlled Fusion 05/2003; 45(7):1079. · 2.42 Impact Factor -
Article: Generation of multiply charged ions at low and high laser-power densities
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ABSTRACT: The PERUN and PALS iodine laser systems and a Nd : YAG laser have been used for studies of ions emitted from various single element laser plasmas, at both low (IL~109 W cm−2) and high (IL~1016 W cm−2) laser intensities. Sufficiently high current densities of low-charge ions, with energies only of hundreds of electronvolt, were produced for starting tests of a considered new hybrid ion source, based on coupling of laser ion source to electron cyclotron resonance plasma. Highly charged ions with charge states about 50+ and with energies even higher than 20 MeV were generated at the highest laser intensities (IL>2×1014 W cm−2). Seven ion sub-groups at least (faster and slower) were recorded and distinguished at these conditions. The existence of an `optimum focus position' in front of the target surface is consistent with the idea that laser interaction with a prepulse-produced plasma improves the conditions for self-focusing. The experimental arrangements and ion diagnostics used for the various laser ion generation experiments are briefly reviewed, as well as our both older and more recent results on the characteristics of the ions, produced at the various laser irradiances, are presented. The results of laser ion implantation experiments using these ions directly (without additional electrostatic acceleration) are also mentioned.Plasma Physics and Controlled Fusion 03/2003; 45(5):585. · 2.42 Impact Factor -
Article: Properties of iodine laser-produced stream of multiply charged heavy ions of different elements
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ABSTRACT: Properties of laser produced stream of ions of high- and medium-Z elements were analyzed in the far expansion zone using time-of-flight method and Thomson parabola spectrograph in experiments performed with the iodine laser system PERUN at IP ASCR, Prague (λ = 1.315 μm, EL ∼ 45 J,τL ∼ 300–700 μs). Ta, Au, and Pb, as well as Co, Sn, and Ag were mainly used as targets onto which a laser power density up to 1×1015 W cm−2 was delivered. Attention is paid to the evolution and comparison of different produced ion groups, and to the number, charge state, energy, and angular distribution of emitted ions. © 2000 American Institute of Physics.Review of Scientific Instruments 01/2000; 71(2):927-930. · 1.37 Impact Factor -
Article: The effect of laser-produced plasma expansion on the ion population
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ABSTRACT: Changes in the ion population during the expansion of Ag, Cu, Pb, and Ta laser-produced plasmas in vacuum were simultaneously measured with two coaxial ion collectors between 82 and 187 cm from a target. The plasma was produced with an iodine laser delivering a power density up to ∼ 1015 W/cm2 onto the target. It was experimentally proved that the charge Q of expanding ions and the corresponding ion current density j are really decreasing with the distance L as Q∝L−2 and j∝L−3, respectively. It implies that the “freezing” of charge states dominates in that interval of L. © 1999 American Institute of Physics.Applied Physics Letters 10/1999; 75(17):2539-2541. · 3.84 Impact Factor -
Article: Angular distributions of ions from laser-produced plasma
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ABSTRACT: This paper presents comprehensive experimental results of angular distributions of ions emitted from laser-produced plasmas. Performing a series of laser shots onto planar Sn, Au, and Pb targets, both the focusing conditions as well as the tilt angle of the target were changed to study the effect on the plasma expansion. In the experiments, the iodine laser system PERUN (laser energy of 30 J in 350 ps of duration) with laser power density of 5 × 1014 W/cm2 was used. For plasma diagnostics four ion collectors and an ion-energy analyzer were applied. Comparison of angular distribution of the fast ion group (velocity within the range of 1–3.4 × 108 cm/s) and of the slow ion group (velocity within the range of 0.14–1 × 108 cm/s) shows distinct differences. The preferred direction of ion emission of these groups depends seriously on focusing conditions. When setting the focus on the in-focus position both groups of ions are peaked in the direction close to the target normal. The maximum charge of ions registered by the ion-energy analyzer were 36+, 51+, and 49+ for Sn, Au, and Pb, respectively.Laser and Particle Beams 03/1999; 17(02):307 - 312. · 1.62 Impact Factor -
Article: New high-power laser facility PALS—prospects for laser–plasma research
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ABSTRACT: In this paper, we report on a new laser facility called PALS (Prague Asterix Laser System), which is currently under construction, and which will house the high-power iodine laser Asterix IV. Upon its completion in late 1999, the PALS facility will be capable of providing single- or multiple-pulse irradiation with a variable pulse duration ranging from 100 to 500 ps. Wavelengths available will be 1.315 [mu]m, 658 nm, and 438 nm. The system will provide one main beam with energy up to 1200 J and two smaller auxiliary beams with a combined energy of up to 100 J. A wide variety of geometries and variable pulse timings is available. We assess PALS' potential for investigating the physics of laser plasmas in inertial confinement fusion, the development and applications of X-ray lasers, X-ray spectroscopy, and radiation transport, using multiple-pulse and extended beam capability.Laser and Particle Beams 03/1999; 17(02):179 - 194. · 1.62 Impact Factor -
Article: Laser plasma X-ray measurements using thermoluminescent dosimeters and Si photodiodes
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ABSTRACT: The energy of X-rays emitted from laser-produced aluminium plasmas is presented. For absolute time-integrated X-ray measurements thermoluminescent dosimeters LiF:Mg,Cu,P (GR 200A), LiF:Mg,Ti (TLD 100), CaF2:Dy (TLD 200) and silicon photodiodes were used. Their calibrated responses to plasma X-rays are compared and discrepancy is discussed.Czechoslovak Journal of Physics 04/1998; 48(3):355-363. · 0.42 Impact Factor
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Institutions
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2012
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Institute of Physics ASCR
Praha, Hlavni mesto Praha, Czech Republic
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1994–2004
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Academy of Sciences of the Czech Republic
- • Ústav fyziky plazmatu
- • Fyzikální ústav
Praha, Hlavni mesto Praha, Czech Republic
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