Андрей Борисович Савельев-Трофимов - Academia.edu (original) (raw)
Papers by Андрей Борисович Савельев-Трофимов
Computer Optics, 2015
We perform a comparative numerical study of the formation of closely spaced focal spots in the fo... more We perform a comparative numerical study of the formation of closely spaced focal spots in the focal plane with diffraction gratings and binary optical elements matched with the Hermite-Gaussian modes. It is shown that low-index modes provide the generation of good-quality focal spots and relative tolerance to chromatic dispersion. Experiments with pulsed and tunable lasers have shown that phase optical elements matched with TEM(1,0) and TEM(1,1) modes show promise for creation of arrays of closely spaced focal spots.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
In this paper, new spectral components formation under filamentation of pre-collimated laser beam... more In this paper, new spectral components formation under filamentation of pre-collimated laser beam in molecular gases is reported. These components arose at the red and blue sides of the initial spectrum and were attributed to the generation of vibrational Raman "spectral solitons" and their cascaded four-wave mixing.
Quantum Electronics, 2009
ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentatio... more ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentation of a collimated beam in argon at a pressure of ~0.8 atm is experimentally realised. Pulses with the initial duration of 55 fs were compressed down to 8 fs, the peak power of the compressed pulse exceeding 20 GW.
Physics of Plasmas, 2012
ABSTRACT A suppression of light-ion acceleration (from surface water contaminants) was observed w... more ABSTRACT A suppression of light-ion acceleration (from surface water contaminants) was observed when a moderate-intensity subpicosecond laser pulse was focused on a thick metal target. Simultaneously, an effective generation of high-energy multicharge ions of the target material (Fe) was experimentally observed. A numerical simulation based on the Boltzmann–Vlasov–Poisson model revealed that this is due to the very specific regime of cleaning contaminants from the target surface by the short weak prepulse preceding the main pulse by more than 10 ns and having an intensity below the surface breakdown threshold. Because this prepulse causes the contaminant layer to boil explosively, a low-density gap forms above the target surface. These conditions are consequently favorable for boosting the energy of heavy ions.
Optics and Spectroscopy, 2009
ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) ... more ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.
JETP Letters, 2009
Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiat... more Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiated by ions (H+, Fe+, Fe2+, Fe3+) with energies ranging from 20 to 100 keV from the plasma of a high-power femtosecond laser pulse with an intensity of 1016 J/(s cm2). These electrons indicate that the energy of an incident ion is almost completely transferred to an electron knocked out of the target. In a range of 6-16 keV, the spectrum of electrons knocked out of the K shell of iron atoms by protons with an energy of 22 ± 2 keV is quasi-exponential with an exponent of 4 keV. For 8-keV electrons, the double differential cross section for ionization by such protons is estimated as 10-7 b/(eV sr).
Journal of the Optical Society of America B, 2010
A scheme for stable shot-to-shot few-cycle pulse production has been realized by launching an ini... more A scheme for stable shot-to-shot few-cycle pulse production has been realized by launching an initially collimated laser beam into a gas tube. We found that the optimum parameters for the sevenfold compression of 55 fs, 5 mJ, Ti:Sapphire laser pulses are the following: 0.8-0.9 atm argon gas pressure and the registration aperture with a diameter of 300-700 m. A technique for the efficient extraction of the self-compressed pulse from the desired position along the filament has been provided by moving the registration aperture along the tube. With this technique, pulses as short as 8 fs were detected at a distance of 1 m from the filament starting position, in agreement with numerical simulations performed using a 3D + time axially symmetric code.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Filaments created during propagation of an ultrashort laser pulses in gases and solids combine hi... more Filaments created during propagation of an ultrashort laser pulses in gases and solids combine high non-linearity with huge intensity and long interaction path. Four-wave mixing, coherent Raman scattering, third harmonic production and others non-linear processes were observed . These studies were made with focused laser beams, when interaction length depends on the Rayleigh length. In this paper we report on thorough investigation of new spectral components formation under filamentation of pre-collimated laser beam in molecular gases. These components arose at the red and blue sides of the initial spectrum and were attributed to the generation of vibrational Raman "spectral solitons" and their cascaded four-wave mixing.
Quantum Electronics, 2009
ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentatio... more ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentation of a collimated beam in argon at a pressure of ~0.8 atm is experimentally realised. Pulses with the initial duration of 55 fs were compressed down to 8 fs, the peak power of the compressed pulse exceeding 20 GW.
Quantum Electronics, 2005
The impurity layer on the surface of a solid target is shown to exert a significant effect on the... more The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of
Quantum Electronics, 2003
The effect of an impurity film lying on the surface of a target in a vacuum of up to 10 Torr on t... more The effect of an impurity film lying on the surface of a target in a vacuum of up to 10 Torr on the ion acceleration in a plasma, which is formed by a 2 x 10-W cm femtosecond laser pulse is studied using the time-offfight and mass spectrometry techniques. It is shown that, under such conditions, the maximum mean energy per unit charge (8 keV) is gained by protons, whereas the ions consti tuting the target substance (Si, Ti) acquire an energy per unit charge of < 1 keV. The use of a < 10 J cm nanosecond laser pulse applied 0.1-100 ms before a femtosecond laser pulse allows the target surface to be efflciently cleaned due to the removal of H-, C-, and O-containing molecules from it. Unlike a continuous thermal heating of a surface, the pulse laser cleaning ensures higher heating temperatures and can be efflciently applied to any solid targets in both the thermal and plasma cleaning modes.
Quantum Electronics, 2000
The effect of intensity, length, and wavelength of an ultrashort laser pulse on the formation of ... more The effect of intensity, length, and wavelength of an ultrashort laser pulse on the formation of a hot electron component in a dense laser-produced plasma was first investigated in a single experiment. For a pulse length of 1 ps (or 200 fs, but with an energy contrast ratio of $ 20), it was shown that the principal mechanism of generation of hot electrons is the resonance absorption of laser radiation and that the temperature of hot electrons depends on the laser pulse intensity I and the wavelength l as T h $ (I l 2) 1a3. The homogenisation of the nanostructures of porous silicon due to a poor contrast ratio or a long duration (1 ps) of the laser pulse lowers the yield of hard x-ray radiation compared to the case of high-contrast 200-fs pulses.
Plasma Physics and Controlled Fusion, 2002
We discuss methods and algorithms of high-temperature laser plasma electron diagnostics based on ... more We discuss methods and algorithms of high-temperature laser plasma electron diagnostics based on hard x-ray yield and ionic time-of-flight (TOF) spectra measurements in comparison with the results of direct electronic spectrum recording, with the help of the electrostatic spectrometer. The latter shows clearly the two-component nature of the electron population, arising at femtosecond laser plasma interaction. `Temperatures&amp;amp;amp;#39; of 200 eV
Optics and Spectroscopy, 2009
ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) ... more ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.
Journal of the Optical Society of America B, 2010
... Citation Daria Uryupina, Maria Kurilova, Anna Mazhorova, Nikolay Panov, Roman Volkov, Stepan ... more ... Citation Daria Uryupina, Maria Kurilova, Anna Mazhorova, Nikolay Panov, Roman Volkov, Stepan Gorgutsa, Olga Kosareva, Andrei Savel'ev, and See Leang Chin, "Few-cycle optical pulse production from ... [CrossRef]; W. Liu, SL Chin, O. Kosareva, IS Golubtsov, and VP Kandidov ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011
We report our experimental results on hard X-ray generation and stability parameters of a laser-d... more We report our experimental results on hard X-ray generation and stability parameters of a laser-driven plasma X-ray source using a melted gallium target irradiated by 2mJ 100fs laser pulse at 1kHz repetition rate. Intense characteristic K-shell emission, including Kα and Kβ, is observed against a background of broadband bremsstrahlung. High brightness and stability from pulse to pulse of hard X-ray
Journal of Experimental and Theoretical Physics, 2006
It is found that the mean charge of tungsten ions in a solid tungsten target cleaned from the sur... more It is found that the mean charge of tungsten ions in a solid tungsten target cleaned from the surface layer of hydrocarbon and oxide compounds and exposed to femtosecond laser radiation with an intensity exceeding 10 16 W/cm 2 attains 22+, while the maximum charge is 29+. The maximum energy of such ions approaches 1 MeV. The corresponding values obtained on a dirty target with the same laser pulse parameters constitute 3+, 5+, and 150 keV. The results of numerical simulation show that such a large maximum charge of ions can be attained owing to the emergence of an electrostatic ambipolar field at the sharp boundary between the plasma and vacuum. The main mechanism of ionization of ions with maximum charges is apparently impact ionization in the presence of an external quasi-static field. In addition, direct above-threshold ionization by this field can also play a significant role. It is also shown that heavy ions in a clean target are accelerated by hot electrons. This leads to the formation of high-energy ions. The effect of recombination on the charge of the ions being detected is analyzed in detail.
Computer Optics, 2015
We perform a comparative numerical study of the formation of closely spaced focal spots in the fo... more We perform a comparative numerical study of the formation of closely spaced focal spots in the focal plane with diffraction gratings and binary optical elements matched with the Hermite-Gaussian modes. It is shown that low-index modes provide the generation of good-quality focal spots and relative tolerance to chromatic dispersion. Experiments with pulsed and tunable lasers have shown that phase optical elements matched with TEM(1,0) and TEM(1,1) modes show promise for creation of arrays of closely spaced focal spots.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
In this paper, new spectral components formation under filamentation of pre-collimated laser beam... more In this paper, new spectral components formation under filamentation of pre-collimated laser beam in molecular gases is reported. These components arose at the red and blue sides of the initial spectrum and were attributed to the generation of vibrational Raman &amp;amp;amp;amp;amp;amp;amp;quot;spectral solitons&amp;amp;amp;amp;amp;amp;amp;quot; and their cascaded four-wave mixing.
Quantum Electronics, 2009
ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentatio... more ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentation of a collimated beam in argon at a pressure of ~0.8 atm is experimentally realised. Pulses with the initial duration of 55 fs were compressed down to 8 fs, the peak power of the compressed pulse exceeding 20 GW.
Physics of Plasmas, 2012
ABSTRACT A suppression of light-ion acceleration (from surface water contaminants) was observed w... more ABSTRACT A suppression of light-ion acceleration (from surface water contaminants) was observed when a moderate-intensity subpicosecond laser pulse was focused on a thick metal target. Simultaneously, an effective generation of high-energy multicharge ions of the target material (Fe) was experimentally observed. A numerical simulation based on the Boltzmann–Vlasov–Poisson model revealed that this is due to the very specific regime of cleaning contaminants from the target surface by the short weak prepulse preceding the main pulse by more than 10 ns and having an intensity below the surface breakdown threshold. Because this prepulse causes the contaminant layer to boil explosively, a low-density gap forms above the target surface. These conditions are consequently favorable for boosting the energy of heavy ions.
Optics and Spectroscopy, 2009
ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) ... more ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.
JETP Letters, 2009
Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiat... more Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiated by ions (H+, Fe+, Fe2+, Fe3+) with energies ranging from 20 to 100 keV from the plasma of a high-power femtosecond laser pulse with an intensity of 1016 J/(s cm2). These electrons indicate that the energy of an incident ion is almost completely transferred to an electron knocked out of the target. In a range of 6-16 keV, the spectrum of electrons knocked out of the K shell of iron atoms by protons with an energy of 22 ± 2 keV is quasi-exponential with an exponent of 4 keV. For 8-keV electrons, the double differential cross section for ionization by such protons is estimated as 10-7 b/(eV sr).
Journal of the Optical Society of America B, 2010
A scheme for stable shot-to-shot few-cycle pulse production has been realized by launching an ini... more A scheme for stable shot-to-shot few-cycle pulse production has been realized by launching an initially collimated laser beam into a gas tube. We found that the optimum parameters for the sevenfold compression of 55 fs, 5 mJ, Ti:Sapphire laser pulses are the following: 0.8-0.9 atm argon gas pressure and the registration aperture with a diameter of 300-700 m. A technique for the efficient extraction of the self-compressed pulse from the desired position along the filament has been provided by moving the registration aperture along the tube. With this technique, pulses as short as 8 fs were detected at a distance of 1 m from the filament starting position, in agreement with numerical simulations performed using a 3D + time axially symmetric code.
CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference, 2009
Filaments created during propagation of an ultrashort laser pulses in gases and solids combine hi... more Filaments created during propagation of an ultrashort laser pulses in gases and solids combine high non-linearity with huge intensity and long interaction path. Four-wave mixing, coherent Raman scattering, third harmonic production and others non-linear processes were observed . These studies were made with focused laser beams, when interaction length depends on the Rayleigh length. In this paper we report on thorough investigation of new spectral components formation under filamentation of pre-collimated laser beam in molecular gases. These components arose at the red and blue sides of the initial spectrum and were attributed to the generation of vibrational Raman "spectral solitons" and their cascaded four-wave mixing.
Quantum Electronics, 2009
ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentatio... more ABSTRACT A new scheme providing self-compression of femtosecond laser radiation upon filamentation of a collimated beam in argon at a pressure of ~0.8 atm is experimentally realised. Pulses with the initial duration of 55 fs were compressed down to 8 fs, the peak power of the compressed pulse exceeding 20 GW.
Quantum Electronics, 2005
The impurity layer on the surface of a solid target is shown to exert a significant effect on the... more The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of
Quantum Electronics, 2003
The effect of an impurity film lying on the surface of a target in a vacuum of up to 10 Torr on t... more The effect of an impurity film lying on the surface of a target in a vacuum of up to 10 Torr on the ion acceleration in a plasma, which is formed by a 2 x 10-W cm femtosecond laser pulse is studied using the time-offfight and mass spectrometry techniques. It is shown that, under such conditions, the maximum mean energy per unit charge (8 keV) is gained by protons, whereas the ions consti tuting the target substance (Si, Ti) acquire an energy per unit charge of < 1 keV. The use of a < 10 J cm nanosecond laser pulse applied 0.1-100 ms before a femtosecond laser pulse allows the target surface to be efflciently cleaned due to the removal of H-, C-, and O-containing molecules from it. Unlike a continuous thermal heating of a surface, the pulse laser cleaning ensures higher heating temperatures and can be efflciently applied to any solid targets in both the thermal and plasma cleaning modes.
Quantum Electronics, 2000
The effect of intensity, length, and wavelength of an ultrashort laser pulse on the formation of ... more The effect of intensity, length, and wavelength of an ultrashort laser pulse on the formation of a hot electron component in a dense laser-produced plasma was first investigated in a single experiment. For a pulse length of 1 ps (or 200 fs, but with an energy contrast ratio of $ 20), it was shown that the principal mechanism of generation of hot electrons is the resonance absorption of laser radiation and that the temperature of hot electrons depends on the laser pulse intensity I and the wavelength l as T h $ (I l 2) 1a3. The homogenisation of the nanostructures of porous silicon due to a poor contrast ratio or a long duration (1 ps) of the laser pulse lowers the yield of hard x-ray radiation compared to the case of high-contrast 200-fs pulses.
Plasma Physics and Controlled Fusion, 2002
We discuss methods and algorithms of high-temperature laser plasma electron diagnostics based on ... more We discuss methods and algorithms of high-temperature laser plasma electron diagnostics based on hard x-ray yield and ionic time-of-flight (TOF) spectra measurements in comparison with the results of direct electronic spectrum recording, with the help of the electrostatic spectrometer. The latter shows clearly the two-component nature of the electron population, arising at femtosecond laser plasma interaction. `Temperatures&amp;amp;amp;#39; of 200 eV
Optics and Spectroscopy, 2009
ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) ... more ABSTRACT The dependence of the parameters of femtosecond laser radiation (55 fs, 3.7 mJ, 800 nm) in a filament on the distance along the filament propagation axis, the diaphragm diameter, and the type and pressure of gas used for filamentation has been studied experimentally.
Journal of the Optical Society of America B, 2010
... Citation Daria Uryupina, Maria Kurilova, Anna Mazhorova, Nikolay Panov, Roman Volkov, Stepan ... more ... Citation Daria Uryupina, Maria Kurilova, Anna Mazhorova, Nikolay Panov, Roman Volkov, Stepan Gorgutsa, Olga Kosareva, Andrei Savel'ev, and See Leang Chin, "Few-cycle optical pulse production from ... [CrossRef]; W. Liu, SL Chin, O. Kosareva, IS Golubtsov, and VP Kandidov ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011
We report our experimental results on hard X-ray generation and stability parameters of a laser-d... more We report our experimental results on hard X-ray generation and stability parameters of a laser-driven plasma X-ray source using a melted gallium target irradiated by 2mJ 100fs laser pulse at 1kHz repetition rate. Intense characteristic K-shell emission, including Kα and Kβ, is observed against a background of broadband bremsstrahlung. High brightness and stability from pulse to pulse of hard X-ray
Journal of Experimental and Theoretical Physics, 2006
It is found that the mean charge of tungsten ions in a solid tungsten target cleaned from the sur... more It is found that the mean charge of tungsten ions in a solid tungsten target cleaned from the surface layer of hydrocarbon and oxide compounds and exposed to femtosecond laser radiation with an intensity exceeding 10 16 W/cm 2 attains 22+, while the maximum charge is 29+. The maximum energy of such ions approaches 1 MeV. The corresponding values obtained on a dirty target with the same laser pulse parameters constitute 3+, 5+, and 150 keV. The results of numerical simulation show that such a large maximum charge of ions can be attained owing to the emergence of an electrostatic ambipolar field at the sharp boundary between the plasma and vacuum. The main mechanism of ionization of ions with maximum charges is apparently impact ionization in the presence of an external quasi-static field. In addition, direct above-threshold ionization by this field can also play a significant role. It is also shown that heavy ions in a clean target are accelerated by hot electrons. This leads to the formation of high-energy ions. The effect of recombination on the charge of the ions being detected is analyzed in detail.