共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Borodziuk A. Kasperczuk T. Pisarczyk S. Yu. Gus'kov J. Ullschmied E. Krousky K. Masek M. Pfeifer K. Rohlena J. Skala M. Kalal J. Limpouch P. Pisarczyk 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):311-317
Efficiency studies of laser driven thin metal disks
acceleration using the first harmonic (λ1=1.315 μm) of
the Prague Asterix Laser System (PALS) and subsequent craters creation
produced by collisions of these disks with massive targets are presented.
Several different disks made of aluminium and copper foils with diameters of
300 μm and 600 μm and thicknesses of 11 μm (Al) and 3.6 μ
m (Cu) were employed. Disks were placed at the distance of either 100 μ
m or 300 μm in front of aluminium massive targets. The following
irradiation conditions were used: the laser beam energy of 120 J, the focal
spot diameter of 200 μm, and the pulse duration of 0.4 ns (FWHM). A
three-frame interferometric system was employed to determine electron
density distributions in plasma corona. Shape and volume of craters were
obtained by crater replica technology and microscopy measurements. The aim
of these investigations was to analyse conditions leading to the most
effective energy transfer in the process of collision of the accelerated
disks with solid targets. The overall efficiency of these processes was
characterized by the volume of craters produced in such targets. 相似文献
2.
The experimental results of a high-power tunable mid-IR laser are presented. The optical parametric oscillator (OPO) with
a 3-mm-thick PPMgCLN crystal was pumped by a 1.064 μm pulse laser. When the pump power of the 1.064 μm laser was 151 W at
10 kHz, and the operating temperature of the PPMgCLN with 5% MgO doping was 100°C, average output power of 23.7 W at 3.91
μm was obtained with a slope efficiency of 18.2% for the idler resonant OPO. The variation of the 3.91 μm output power was
about ±4% in 10 min continuous operation. The beam quality factor M
2 was less than 2.6. The average output power of 27.4 W at 3.91 μm was also obtained with 151 W pump power and the slope efficiency
of 20.9% for the signal resonant OPO by changing the coating parameters of the OPO cavity mirrors. The mid-IR wavelength tunability
of 3.7–4.0 μm can be achieved by adjusting the temperature of a 29 μm period PPMgCLN crystal from 200 to 30°C. 相似文献
3.
M. Inguscio P. Minguzzi A. Moretti F. Strumia M. Tonelli 《Applied Physics A: Materials Science & Processing》1979,18(3):261-270
The operation of a cw FIR laser in the presence of a strong electric field is described. A hybrid metal-dielectric waveguide
is used and the cavity length is scanned to study how the frequency and power of the laser depend on the field strength. The
results have also been checked by heterodyning with a conventional reference laser. We report the results obtained for the
496 μm line of CH3F and the 70.5 μm and 119 μm lines of CH3OH. A large frequency tunability of almost ±40 MHz is obtained in the best case with power levels in the mW range. A very
simple theoretical model accounts for the experimental results. We also report the appearance of a new FIR line at about 204
μm when CH3OH is pumped by the 9 μmP(34) of CO2 in the presence of an electric field larger than 1.2 KV/cm. 相似文献
4.
V. A. Andronov S. A. Bel’kov A. V. Bessarab I. N. Voronich S. G. Garanin A. A. Gorbunov V. N. Derkach G. V. Dolgoleva A. I. Zaretskii V. M. Izgorodin B. N. Ilyushechkin G. A. Kirillov G. G. Kochemasov Yu. V. Kuratov V. I. Lazarchuk V. A. Lebedev V. M. Murugov L. S. Mkhitar’yan A. V. Okutin S. I. Petrov A. V. Pinegin N. N. Rukavishnikov A. N. Razin A. V. Ryadov A. V. Senik N. A. Suslov S. A. Sukharev V. A. Tokarev 《Journal of Experimental and Theoretical Physics》1997,84(3):485-488
The results of the first experiments devised to investigate the mixing of thin layers of Al and Au during the laser acceleration
of flat three-layer targets of Si (5 μm), Al (2 μm), and Au (0.05–0.26 μm) by radiation converted to the second harmonic from the Iskra-4 iodine laser with an intensity of 4×1013−7×1013 W/cm2 (τ
0.5∼1 ns), which acts on the Si side of the target. A method for detecting the occurrence of mixing is developed. It is established
that under the experimental conditions the thickness of the mixing region is at least ∼0.15 μm. The results of a theoretical analysis of the evolution of the disturbances leading to mixing are presented.
Zh. éksp. Teor. Fiz. 111, 882–888 (March 1997)
Deceased. 相似文献
5.
6.
Adel Bousseksou Sophie Bouchoule Moustafa El Kurdi Martin Strassner Isabelle Sagnes Paul Crozat Joel Jacquet 《Optical and Quantum Electronics》2006,38(15):1269-1278
We report on the design, fabrication, and characterization of InP-based 1.55 μm wavelength large diameter (50 μm) electrically pumped vertical external cavity surface emitting lasers (EP-VECSELs). The hybrid device consists of a half
vertical cavity surface emitting laser (1/2-VCSEL) structure assembled with a concave dielectric external mirror. The 1/2-VCSEL
is monolithically grown on InP substrate and includes a semiconductor Bragg mirror and a tunnel junction for electrical injection.
Buried (BTJ) and ion implanted (ITJ) tunnel junction electrical confinement schemes are compared in terms of their thermal
and electrical characteristics. Lower thermal resistance values are measured for BJT, but reduced current crowding effects
and uniform current injection are evidenced for ITJ. Using the ITJ technique, we demonstrate Room-Temperature (RT) continuous-wave
(CW) single transverse mode laser operation from 50-μm diameter EP-VECSEL devices. We show that the experimental laser optical output versus injected current (L–I) curves are well-reproduced by a simple analytical thermal model, consistent with the thermal resistance measurements performed
on the 1/2-VCSEL structure. Our results indicate that thermal heating is the main mechanism limiting the maximum CW output
power of 50-μm diameter VECSELs, rather than current injection inhomogeneity. 相似文献
7.
Modeling of UV pulsed-laser ablation of metallic targets 总被引:1,自引:0,他引:1
S. Amoruso 《Applied Physics A: Materials Science & Processing》1999,69(3):323-332
A model to describe the laser ablation of metallic targets is presented. It accounts for the main physical processes involved
in the laser–solid–plasma interaction by considering the photon absorption and the ionization mechanisms that are active in
the plasma, as well as the laser-produced plasma kinetics. The model is used to simulate the laser ablation of aluminum targets
irradiated with a 6-ns UV laser pulse at 0.35 μm, and the results are compared with experimental findings. Calculations show
that all the investigated plasma parameters strongly depend on the laser intensity until a roll-off is reached at irradiance
≥1.5 GW cm-2. The satisfactorily good agreement between model predictions and experimental findings confirms that laser–plasma interaction
processes and plasma kinetics play a relevant role during nanosecond laser ablation of metals in the laser intensity range
of concern in this study.
Received: 12 February 1999 / Accepted: 12 April 1999 / Published online: 7 July 1999 相似文献
8.
S.I. Dolgaev J.M. Fernández-Pradas J.L. Morenza P. Serra G.A. Shafeev 《Applied Physics A: Materials Science & Processing》2006,83(3):417-420
We report the growth of conical microstructure arrays on a stainless steel substrate under multi-pulsed Nd:YAG laser irradiation
(wavelength of 1.064 μm, pulse duration of 300 ns, repetition rate of 5 kHz) at atmospheric air pressure. The average period
of microcones is 70 μm, and they protrude 50–60 μm above the substrate. At an air pressure of 1 Pa, the well-defined conical
shape is lost and the resulting microstructure shows a smaller period and height. At 10-3 Pa, only small protrusions separated by about 5 μm are observed. The different mechanisms involved in the growth of conical
microstructures are discussed.
PACS 42.62.-b; 81.65.-b 相似文献
9.
An analytical model of K
α radiation of thin laser targets has been developed. It has been shown that, for such targets, the motion of fast electrons
is significant not only in the target itself but also in vacuum. The considered dependences for the free path length of a
fast electron and for the absorption coefficient of laser radiation on the laser intensity with allowance for the electron
motion in vacuum make it possible to match the results of the proposed model with the experimental data on generation of K
α radiation in wide ranges of laser intensities (1018–1021 W/cm2) and thicknesses (1–100 μm) of targets. 相似文献
10.
D. Batani R. Benocci R. Dezulian R. Redaelli F. Canova H. Stabile G. Lucchini V. Malka J. Faure M. Koenig E. Krousky K. Masek M. Pfeifer J. Skala R. Dudzak J. Limpouch V. Tikhoncuk P. Nicolai 《The European physical journal. Special topics》2009,175(1):65-70
Smoothing of laser beam non-uniformities using gas jets has been studied. The experiment has been performed with the PALS
laser working at 0.44 μm with an intensity of about 1015 W/cm2. The laser beam has been split in two by a prism thus creating an artificial large-scale non-uniformity (≈90 μm). We recorded
time resolved and static images of laser-gas jet interaction with and without an Al target. Multi 1D and 2D simulations show
that such interaction acts redistributing the over-intensities over larger surface. This effect has to be attributed to ionization
processes with consequent laser beam refraction. Results show that Argon gas jet produces a strong refraction of the laser
beam thus strongly reducing the initial two spots separation. 相似文献
11.
Pogorelsky I. V. Polyanskiy M. N. Babzien M. Yakimenko V. Dover N. P. Palmer C. A. J. Najmudin Z. Schreiber J. Shkolnikov P. Dudnikova G. 《Laser Physics》2011,21(7):1288-1294
A picosecond CO2 laser was used successfully in a number of experiments exploring advanced methods of particle acceleration [1]. Proton acceleration
from gas-jet plasma exemplifies another advantage of employing the increase in laser wavelength from the optical to the mid-IR
region. Recent theoretical- and experimental-studies of ion acceleration from laser-generated plasma point to better ways
to control the ion beam’s energy when plasma approaches the critical density. Studying this regime with solid-state lasers
is problematic due to the dearth of plasma sources at the critical electron density ∼1021 cm−3, corresponding to laser wavelength λ = 1 μm. CO2 laser offers a solution. The CO2 laser’s 10 μm wavelength shifts the critical plasma density to 1019 cm−3, a value attainable with gas jets. Capitalizing on this approach, we focused a circular polarized 1-TW CO2 laser beam onto a hydrogen gas jet and observed a monoenergetic proton beam in the 1–2 MeV range. Simultaneously, we optically
probed the laser/plasma interaction region with visible light, revealing holes bored by radiation pressure, as well as quasi-stationary
soliton-like plasma formations. Our findings from 2D PIC simulations agree with experimental results and aid in their interpretation. 相似文献
12.
G. Durry N. Amarouche L. Joly X. Liu B. Parvitte V. Zéninari 《Applied physics. B, Lasers and optics》2008,90(3-4):573-580
The 2.7 μm spectral range is highly suitable for the in situ monitoring of atmospheric H2O using compact balloonborne laser diode spectrometers. Water vapour spectroscopic parameters of the 202
101 and the 413
414 transitions of the ν3 band are revisited in this spectral region using a new distributed-feedback InGaAsSb laser diode emitting at 2.63 μm. Accurate
line strengths are provided which are well adapted for the in situ probing of the middle atmosphere. Our measurements are
thoroughly compared to an existing molecular database, laboratory measurements and ab-initio calculations. A laser hygrometer
was developed for operation from small stratospheric balloons using this new laser diode technology, with emission at 2.6 μm.
The realized sensor is described and results from a recent test-flight are reported.
PACS 07.57.Ty; 92.60 Jq 相似文献
13.
Yu.P. Averin D.V. Balin V.R. Bom A.M. Demin D.L. Demin A.E. Drebushko V.P. Dzhelepov C.W.E. van Eijk V.V. Filchenkov A.N. Golubkov N.N. Grafov V.G. Grebinnik S.K. Grishechkin V.G. Klevtsov A.D. Konin A.A. Kukolkin S.V. Medved' A.B. Modenov V.A. Nazarov V.I. Pryanichnikov V.Ia. Rozhkov A.I. Rudenko S.M. Sadetsky G.G. Semenchuk V.T. Sidorov Yu.V. Smirenin I.I. Sukhoi V.V. Travkin N.I. Voropaev A.A. Yukhimchuk V.G. Zinov S.V. Zlatoustovskii 《Hyperfine Interactions》1999,118(1-4):121-125
Muon catalyzed fusion in a dense triple mixture of hydrogen isotopes was investigated for the first time. The experimental
method is based on the registration of neutrons from dtμ fusion by a full absorption detector in 4π geometry. The measurements were performed in H/D/T mixture at T=21 K and φ≃ 1.1 LHD using four sets of isotope concentrations. The basic parameters of the dtμ cycle (neutron yield, cycling rate and total sticking) in H/D/T mixtures obtained from neutron time distributions are presented
and discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
We have theoretically investigated the thermal characteristics of double-channel ridge–waveguide InGaAs/InAlAs/InP quantum
cascade lasers (QCLs) using a two-dimensional heat dissipation model. The temperature distribution, heat flow, and thermal
conductance (G
th) of QCLs were obtained through the thermal simulation. A thick electroplated Au around the laser ridges helps to improve
the heat dissipation from devices, being good enough to substitute the buried heterostructure (BH) by InP regrowth for epilayer-up
bonded lasers. The effects of the device geometry (i.e., ridge width and cavity length) on the G
th of QCLs were investigated. With 5 μm thick electroplated Au, the G
th is increased with the decrease of ridge width, indicating an improvement from G
th=177 W/K⋅cm2 at W=40 μm to G
th=301 W/K⋅cm2 at W=9 μm for 2 mm long lasers. For the 9 μm×2 mm epilayer-down bonded laser with 5 μm thick electroplated Au, the use of InP
contact layer leads to a further improvement of 13% in G
th, and it was totally raised by 45% corresponding to 436 W/K⋅cm2 compared to the epilayer-up bonded laser with InGaAs contact layer. It is found that the epilayer-down bonded 9 μm wide BH
laser with InP contact layer leads to the highest G
th=449 W/K⋅cm2. The theoretical results were also compared with available obtained experimentally data. 相似文献
15.
We report a continuous-wave singly resonant optical parametric oscillator (SRO) with more than 12 W of idler power at 3414
nm when it was operated at 30°C. The SRO was directly pumped by a single-frequency, ytterbium-doped fiber laser with 49 W
linear polarization pump powers, and based on 50 mm long periodically poled MgO:LiNbO3 crystal (PPMgLN) in two-mirror linear cavity with 30.5 μm grating period. It’s pump power at threshold was 5.4 W. The slope-efficiency
and quantum-limited performance reached 26 and 79.2%, respectively. The beam polarization matched the e → e + e interaction in crystal. The idler waves were temperature tuned in the range of 3654 to 3811 nm and 3248 to 3414 nm based
on two 50 mm long PPMgLN with 29.5 and 30.5 μm grating period. To the best of our knowledge, this is the highest continuouswave
mid-IR output obtained for a fiber laser pumped optical parametric oscillator (OPO). 相似文献
16.
Near-infrared laser action of atomic carbon was obtained using a hollow cathode discharge tube. Besides the known 1.4543 μm
and 1.0691 μm laser lines, cw laser operation at 1.0683 μm, 0.9658 μm, and 0.9406 μm wavelength was observed for the first
time. The source of carbon was due to dissociation of CO, CO2 or CH4 added to the He buffer gas. 相似文献
17.
M. Jackson E.M. Telles M.D. Allen K.M. Evenson 《Applied physics. B, Lasers and optics》2001,72(7):815-818
A significantly improved far-infrared laser has been used to generate optically pumped laser emissions from 26 to 150 μm for
CD3OH. Using an X–V-pumping geometry, several new laser emissions have been found for CD3OH. In addition, an increase in power, by factors from 10 to 1000, for many of the previously known shorter-wavelength laser
lines, below 100 μm, has been observed. Frequency measurements for several lines have also been performed and have been reported
to a fractional uncertainty up to ±2×10-7, permitting the spectroscopic assignment of the laser transition. One of the frequency-measured lines, 44.256 μm observed
using the 10R34 pump, has confirmed the assignment of the previously reported FIR emission (n,K;J)=(1,7;20)?(0,8;20)A in the
ground vibrational state.
Received: 26 October 2000 / Published online: 7 February 2001 相似文献
18.
V. V. Ivanov A. V. Kutsenko I. G. Lebo A. A. Matsveiko Yu. A. Mikhailov V. P. Osetrov A. I. Popov V. B. Rozanov G. V. Sklizkov A. N. Starodub V. V. Nikishin V. F. Tishkin 《Journal of Experimental and Theoretical Physics》1999,89(4):689-695
The paper presents results of experiments performed on the Pico facility in which foils were heated by laser radiation, and
anomalously fast burn-through of foils by a structured laser beam was detected. Comparison with two-dimensional calculations
has allowed us to suggest a tentative mechanism for the effect under investigation. The targets in the experiments were thin
aluminum foils of thickness 3 to 40 μm. The flux density of laser radiation on the target surface varied between 1013 and 1014 W/cm2. We detected a strong dependence of the transmitted energy on the foil thickness and the shortening of the transmitted laser
pulse. Penetration of laser radiation through foils with thicknesses considerably larger than 3 μm has been observed, although it was stated in earlier publications [V. V. Ivanov, A. K. Knyazev, A. V. Kutsenko, et al., Kratk. Soobshch. Fiz. FIAN No. 7–8, 37 (1997)]; A. é. Bugrov, I. N. Burdonskii, V. V. Gol’tsov et al., Zh. éksp. Teor. Fiz. 111, 903 (1997) [JETP 84, 903 (1997)] that, at the laser radiation parameters used in our experiment, the evaporated layer of the foil could not be
thicker than 2 μm. Two-dimensional calculations have allowed us to interpret this effect in terms of local “piercing” of the target at spots
on the target surface where the radiation intensity has its peaks. The possibility of reducing these peaks by using a symmetrizing
prepulse is discussed in the paper.
Zh. éksp. Teor. Fiz. 116, 1287–1299 (October 1999) 相似文献
19.
F. Kottmann W. Amir F. Biraben C. A. N. Conde S. Dhawan T. W. Hänsch F. J. Hartmann V. W. Hughes O. Huot P. Indelicato L. Julien P. Knowles S. Kazamias Y.-W. Liu F. Mulhauser F. Nez R. Pohl P. Rabinowitz J. M. F. dos Santos L. A. Schaller H. Schneuwly W. Schott D. Taqqu J. F. C. A. Veloso 《Hyperfine Interactions》2001,138(1-4):55-60
A measurement of the 2S Lamb shift in muonic hydrogen (μ−p) is being prepared at the Paul Scherrer Institute (PSI). The goal of the experiment is to measure the energy difference
ΔE(25
P
3/2−23
S
1/2) by laser spectroscopy (λ≈6μm) to a precision of 30 ppm and to deduce the root mean square (rms) proton charge radius with
10−3 relative accuracy, 20 times more precise than presently known.
An important prerequisite to this experiment is the availability of long-lived μp2S
-atoms. A 2S-lifetime of ∼1 μs – sufficiently long to perform the laser experiment – at H2 gas pressures of 1–2 hPa was deduced from recent measurements of the collisional 2S-quenching rate. A new low-energy negative muon beam yields an order of magnitude more muon stops in a small low-density gas
volume than a conventional cloud muon beam. A stack of ultra-thin carbon foils is the key element of a fast detector for keV-muons.
The development of a 2 keV X-ray detector and a 3-stage laser system providing 0.5 mJ laser pulses at 6 μm is on the way.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
20.
We report a ZGP OPO system capable of producing >6 W at a signal wavelength of 3.80 μm and an idler wavelength of 4.45 μm.
The pumping source is the Tm,Ho:GdVO4 laser operated at 2.049 μm with an M
2 of 1.07. The ZGP OPO generated a total combined output power of 6.1 W at signal wavelength and idler wavelength under pumping
power of 18.3 W, and an M
2 of 1.7 for OPO output was obtained. 相似文献