共查询到20条相似文献,搜索用时 500 毫秒
1.
V. S. Belyaev D. V. Kovkov A. P. Matafonov G. F. Karabadzhak G. G. Raikunov A. Ya. Faenov S. A. Pikuz Jr. I. Yu. Skobelev T. A. Pikuz D. A. Fokin V. E. Fortov G. N. Ignat’ev S. V. Kapitanov P. S. Krapiva K. E. Korotkov 《JETP Letters》2013,97(12):681-685
It is proposed to use a high rate of collisional ionization in a superdense laser plasma to generate incoherent femtosecond X-ray pulses. The calculations indicate that the use of picosecond laser pulses with a contrast of about 1010 will allow the generation of an X-ray pulse with a duration of about 10 fs. The adequacy of the proposed model of the excitation of linear X-ray radiation from the plasma has been tested in the experiments with a picosecond laser of a moderately high contrast. 相似文献
2.
V. S. Belyaev V. I. Vinogradov A. S. Kurilov A. P. Matafonov V. P. Andrianov G. N. Ignat’ev A. Ya. Faenov T. A. Pikuz I. Yu. Skobelev A. I. Magunov S. A. Pikuz Jr. B. Yu. Sharkov 《Journal of Experimental and Theoretical Physics》2004,98(6):1133-1137
Neutron production as a result of the reaction 2H(d, n)3He in a picosecond laser plasma is reported. A considerable neutron yield of 5×104 per pulse is obtained for the first time in a picosecond laser plasma on the surface of a solid deuterated target at laser radiation intensity of 3×1017 W/cm2. 相似文献
3.
A nonlinear optical method has been proposed for probing the evolution of a plasma and energy transfer processes in the microvolume
of a transparent dielectric using the third-harmonic probe signal. The electron self-trapping time has been estimated as t = 150 ± 80 fs. A decrease in the third-harmonic probe signal has been detected at the picosecond time scale; this decrease
can be attributed to a change in the third-order susceptibility χ(3) of a fused silica sample modified by laser radiation. 相似文献
4.
V. S. Belyaev V. I. Vinogradov A. P. Matafonov A. M. Chekmarev A. G. Karabadzhak 《Laser Physics》2006,16(3):477-487
The interaction of high-power picosecond laser radiation with solid targets is experimentally studied for the first time at various spectral distributions of a chirped laser pulse. The interaction of the high-power laser radiation with the target is studied at four regimes of the experimental setup: (i) at a relatively high contrast (103) in the picosecond (Δt ~ 25 ps) range, (ii) at a relatively low contrast (3 × 101) in the picosecond (Δt ~ 25 ps) range, (iii) with spectral distortions of the chirped pulse, and (iv) with a strongly modulated spectrum of the chirped pulse. The results obtained reveal a strong dependence of the atomic and nuclear processes in the laser picosecond plasma on the spectral distribution of the chirped laser pulse. The prospects for the application of the spectral interferometry of chirped pulses for the online control of the parameters of the high-power laser radiation are demonstrated. 相似文献
5.
V. S. Belyaev V. I. Vinogradov A. P. Matafonov V. P. Krainov V. S. Lisitsa V. P. Andrianov G. N. Ignatyev 《Laser Physics》2006,16(12):1647-1657
Experimental results on the effect of picosecond and nanosecond prepulses on the neutron yield in laser picosecond plasma on the surface of solid (CD2)n targets at a laser intensity of 1018 W/cm2 are presented. It is demonstrated that the picosecond (nanosecond) prepulse decreases the neutron yield at a laser prepulse intensity of higher than 1013 (1012) W/cm2. The estimates indicate three possible mechanisms for the realization of the observed effect: stimulated Mandelstam-Brillouin scattering of the main pulse by the preplasma, channels of the generation of fast ions, and their possible deceleration in the preplasma. The results of calculations are compared with the experimental data. 相似文献
6.
V. S. Belyaev V. I. Vinogradov A. S. Kurilov A. P. Matafonov V. S. Lisitsa V. P. Gavrilenko A. Ya. Faenov T. A. Pikuz I. Yu. Skobelev A. I. Magunov S. A. Pikuz Jr. 《Journal of Experimental and Theoretical Physics》2004,99(4):708-718
We present the results of our measurements of the spectra for multicharged ions in a plasma produced by moderately intense (about 1017Wcm?2) picosecond laser pulses. They suggest the existence of intense plasma oscillations with a frequency appreciably lower than the frequency of the laser radiation. The observed spectrum for the plasma satellites of the Lyman Lyα doublet of the hydrogenic F IX ion in a dense plasma was modeled theoretically. The resulting doublet profile was shown to have a complex structure that depends non-trivially both on the plasma density and on the frequency and amplitude of the plasma oscillations. The positions of the satellites and their separations allowed them to be associated with intense electrostatic oscillations with an amplitude of (4–6)×108Vcm?1 and a frequency near (0.7–1)×1015s?1. Assuming the oscillation frequency to be determined by the strength of the magnetic field B generated in the plasma, we obtained an estimate of B that is in reasonable agreement with other measurements and estimates of this quantity. Our theoretical analysis allowed explanation of the emission spectra observed when flat fluoroplastic targets were heated by intense picosecond laser pulses. 相似文献
7.
R. A. Smith V. Barrow J. Edwards G. Kiehn O. Willi 《Applied physics. B, Lasers and optics》1990,50(3):187-192
The scaling of recombination XUV lasers to shorter wavelengths requires laser plasmas produced at initial electron densities close to solid. With pump laser pulses longer than a few tens of picoseconds the hydrodynamic motion of the plasma during the interaction makes this difficult to achieve. In contrast, when picosecond laser pulses are used the laser energy is absorbed close to solid density since the plasma expansion is insignificant during the laser pulse. This results in hot near solid density plasmas which are needed for hydrogenic recombination X-ray lasers operating in the water window. Experimental observations have shown that a fully ionized aluminium plasma with a temperature of about 400 eV and a density well above 1023 cm–3 is produced when an aluminium target is irradiated with a single 3.5 ps high power KrF laser pulse. 相似文献
8.
J. Jandeleit G. Urbasch H. D. Hoffmann H. -G. Treusch E. W. Kreutz 《Applied Physics A: Materials Science & Processing》1996,63(2):117-121
The ablation process of thin copper films on fused silica by picosecond laser pulses is investigated. The ablation area is characterized using optical and scanning electron microscopy. The single-shot ablation threshold fluence for 40 ps laser pulses at 1053 nm has been determinated toF
thres = 172 mJ/cm2. The ablation rate per pulse is measured as a function of intensity in the range of 5 × 109 to 2 × 1011 W/cm2 and changes from 80 to 250 nm with increasing intensity. The experimental ablation rate per pulse is compared to heat-flow calculations based on the two-temperature model for ultrafast laser heating. Possible applications of picosecond laser radiation for microstructuring of different materials are discussed. 相似文献
9.
Light scattering from nonequilibrium electron-hole plasma excited by picosecond laser pulses in GaAs
A picosecond dye laser is used to excite electron-hole plasma of density between 1018 to 1019 cm-3 in GaAs. The plasma density and distribution function within ? 20 psec of excitation is probed by Raman scattering. The lineshape of the single particle excitation spectra of the plasma can be explained only by assuming that the electron distribution function is in nonthermal equilibrium. 相似文献
10.
Transient stimulated Raman scattering (TSRS) of picosecond dye laser pulses in ethanol has been investigated experimentally. In particular some temporal features of TSRS from the C-H stretching mode (2928 cm-1) in ethanol have been studied with a Photochron II streak camera with subpicosecond time resolution. It is shown that the use of TSRS provides a simple method for producing picosecond pulses tunable over the spectral region ≈492–532 nm and 691–772 nm by tuning a passively mode-locked Rhodamine 6G dye laser from 575–630 nm. 相似文献
11.
A laser activated silicon switch generates the sweeping voltage for a picosecond streak camera. With a Photochron streak tube shot-to-shot jitter has been reduced to ?±15 ps for writting speeds in excess of 2×108 ms-1. 相似文献
12.
G.I. Brukhnevitch V.K. Chevokin Yu.S. Kasyanov V.V. Korobkin A.A. Malyutin A.M. Prokhorov M.C. Richardson M.Ya. Schelev B.M. Stepanov 《Physics letters. A》1975,51(4):249-250
Direct picosecond measurements of X-ray laser plasma radiation were performed with a high-speed X-ray image-converter camera (ICC). This camera operates in the single-frame mode with an exposure time ranging from 5 ns to 0.5 μs and in the streak mode with 5 × 109 to 5 × 107 cm/s streak velocities. Its temporal resolution in the streak mode was calculated to be about 7 ps. A plasma was created by focussing 10 ps 1 to 2 joule laser pulses onto a titanium target placed in a vacuum chamber. The halfwidth of the recorded X-ray pulses varied from 30 to 60 ps. 相似文献
13.
A. A. Kaminskii 《Doklady Physics》2016,61(12):586-589
High-order stimulated Raman scattering (SRS) has been revealed in a LuAlO3 crystal upon stationary picosecond laser excitation. All recorded Stokes and anti-Stokes χ(3)-nonlinear laser components are attributed to three SRS-promoting А g vibrational modes of its octahedral anionic units (AlO3)–3. 相似文献
14.
Sudhanshu S Jha 《Pramana》1973,1(2):88-97
The problem of heating of a solid target to generate a nonequilibrium plasma by subnanosecond laser pulses is considered.
For an appreciable absorption of energy from a Nd-glass laser, the critical density of the electrons in the plasma turns out
to be 1021 cm−3. These electrons can be heated up to 107 K or more by using pulses of about 10 picosecond duration and absorbed energy flux of the order of 1021 erg cm−2 sec−1. Starting from neutral atoms in a solid with a high atomic number, e.g., Z=26, for times in the picosecond regime the relevant
rate equations are solved analytically to predict densities of the atoms at different ionization levels. It is shown that
during such a short time the population density of the ions isoelectronic to neon builds up to a very large amount. This in
turn leads to the population inversion in the 4s → 3p soft x-ray laser transition, via the electron-impact excitation of the
4s level of the isoelectronic neon ion. For the effective pumping times of the order of 5 picoseconds, a gain of the order
of 102 db cm−1 is predicted for the laser transition in Fe XVII, Co XVIII or Cu XX. 相似文献
15.
Phase conjugation with conversion efficiences of up to 50% has been obtained in DODCI and other saturable absorbers with picosecond pulses from a mode-locked dye laser. Reflectivity shows a quadratic dependence on pump intensity up to ~500 MW cm-2. 相似文献
16.
T. I. Karu P. G. Kryukov V. S. Letokhov Yu. A. Matveetz V. A. Semchishen 《Applied Physics A: Materials Science & Processing》1981,24(3):245-247
The action of powerful pulsed picosecond radiation from a Nd: YAG laser (λ=530 nm, pulse energy: 0.01 J, intensity: 2GW/cm2) and an argon laser (λ=515 nm, power: 50 mW) on protoporphyrin-IX dimethylether in three solvents (trichlormethane, carbon
tetrachloride, dioxane) has been studied. Under continuous irradiation the quantum yield and resulting products do not differ
materially from the ones produced under mercury lamp irradiation. When irradiation is performed by powerful laser pulses of
picosecond duration the quantum yield of photodecomposition of protoporphyrin-IX dimethylether inereases substantially: by
10 in dioxane, by 4 in carbon tetrachloride and by 100 in trichlormethane. It is assumed that a quite different mechanism
of multistep excitation is responsible for photodecomposition under powerful picosecond pulses. 相似文献
17.
The dependence of photocurrent on laser intensity has been studied up to the damage threshold of tungsten using 30 ps pulses from a Nd:YAG laser. For intensities below ~1 GW/cm2, four-photon photoelectric emission is observed. For higher intensities three-photon assisted thermionic emission dominates. A generalized Fowler-DuBridge theory accounts quantitatively for our observations. A polycrystal surface cleaned by picosecond laser pulses has a work function different from surfaces cleaned by ordinary heating methods. 相似文献
18.
《Solid State Communications》1986,59(3):173-176
Using picosecond time resolved spectroscopy, we study the extinction kinetics of the optical transmission of CdSe platelets induced by strong optical pumping. We investigate particularly the all-optical gate capabilities (resulting from the bandgap shrinkage due to the Mott transition) for laser beams the wavelength of which ranges from 676 to 678 nm. The electron-hole plasma density necessary to enable the optical switching is determined (ϱ ∼ 2 × 1017cm−3 at 20K). The switch-off time (i.e. the transparency recovery time) is also studied at different wavelengths by picosecond spectroscopy. 相似文献
19.
V. S. Belyaev V. I. Vinogradov A. S. Kurilov A. P. Matafonov V. S. Lisitsa V. P. Gavrilenko A. Ya. Faenov T. A. Pikuz I. Yu. Skobelev A. I. Magunov S. A. Pikuz Jr. 《JETP Letters》2003,78(11):703-706
The X-ray lines of ions in a solid target interacting with picosecond laser pulses of moderate intensity (2×1017 W/cm2) were measured on the “Neodim” laser facility. X-ray Ly α emission spectra of hydrogen-like fluorine ions were observed. Satellite lines were also observed, evidencing the presence of intense plasma oscillations. The positions and separation between the satellites allow their assignment to the intense electrostatic oscillations with an amplitude larger than 108 V/cm and a frequency of about 7× 1014 s?1 that is noticeably lower than the laser frequency ωlas~1.8×1015 s?1. It is suggested that these oscillations may be due to strong plasma turbulence caused by the development of plasma oscillations of the Bernstein-mode type under the action of a strong magnetic field generated in plasma. The experimental results are compared with the calculated spectra of multicharged ions. 相似文献
20.
V. S. Belyaev V. I. Vinogradov A. S. Kurilov A. I. Magunov A. P. Matafonov T. A. Pikuz I. Yu. Skobelev A. Ya. Faenov 《Journal of Experimental and Theoretical Physics》2003,96(5):897-903
X-ray emission spectra of the plasma created at the surface of magnesium, aluminum, copper, and zinc targets heated by 1-ps laser pulses with a peak power density of up to 1016 W/cm2 were measured. The effect of a picosecond prepulse on the spectra was studied for various power densities and intensity contrasts of the main laser pulse. It is established that the emission spectra of laser plasmas are weakly affected by a change from 105 to 107 in the main pulse contrast relative to the first prepulse. Variations in the parameters of emission from aluminum and magnesium plasmas were calculated using relative intensities and widths of the resonance lines of H-and He-like ions and their two-electron satellite peaks. 相似文献