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1.
The plasma cathode design concept is applied to an Ar laser for the first time. The sliding discharge is used as a plasma cathode for the main laser discharge. The laser operates at atmospheric pressure with a gas mixture of Ar/He/SF6. Results concerning the dependence of the laser performance on the gas mixture flow rates and charging voltage are presented. The temporal behavior of the laser output is also presented. Output energies as high as 2 mJ, efficiency and specific energy extraction values up to 1.3×10−2% and 0.02 J/l respectively, at atmospheric pressure, are obtained. The spectroscopic examination of the output shows that lasing at 1.79 and 1.27 μm is obtained with approximately equal line intensities. 相似文献
2.
Experimental results on the generation of 1.54 μm eye-safe radiation in pure CH4, CH4:He and CH4:Ar mixtures pumped by the fundamental of an Nd:YAG laser, using the stimulated Raman scattering (SRS) technique, are described. A decrease in the energy conversion efficiency and degradation in the beam quality of S1 was observed in pure CH4 at high pump energies. This problem was overcome in CH4:He and CH4:Ar mixtures. Compared with the first Stokes (1.54 μm) energy conversion efficiency in pure CH4, at a pump energy of 126 mJ, an enhancement of 50% in energy conversion efficiency was observed in the CH4:Ar mixture (60% argon concentration) and as much as 100% in the CH4:He mixture (60% helium concentration). The use of these buffer gas mixtures improved the spatial beam quality of the Stokes radiation considerably and also resulted in raising the pump threshold for optical breakdown of the Raman gain medium. 相似文献
3.
The He-Ar-Cu+ IR laser operates in a hollow-cathode discharge, typically in a mixture of helium with a few-% Ar. The population inversion
of the Cu+ ion levels, responsible for laser action, is attributed to asymmetric charge transfer between He+ ions and sputtered Cu atoms. The Ar gas is added to promote sputtering of the Cu cathode. In this paper, a hybrid modeling
network consisting of several different models for the various plasma species present in a He-Ar-Cu hollow-cathode discharge
is applied to investigate the effect of Ar concentration in the gas mixture on the discharge behavior, and to find the optimum
He/Ar gas ratio for laser operation. It is found that the densities of electrons, Ar+ ions, Arm
* metastable atoms, sputtered Cu atoms and Cu+ ions increase upon the addition of more Ar gas, whereas the densities of He+ ions, He2
+ ions and Hem
* metastable atoms drop considerably. The product of the calculated Cu atom and He+ ion densities, which determines the production rate of the upper laser levels, and hence probably also the laser output power,
is found to reach a maximum around 1–5 % Ar addition. This calculation result is compared to experimental measurements, and
reasonable agreement has been reached.
Received: 14 October 2002 /
Revised version: 28 November 2002 / Published online: 19 March 2003
RID="*"
ID="*"Corresponding author. Fax: +32-3/820-23-76, E-mail: annemie.bogaerts@ua.ac.be 相似文献
4.
Experimental results on the generation of 1.54 μm eye-safe radiation in pure CH4, CH4:He and CH4:Ar mixtures pumped by the fundamental of an Nd:YAG laser, using the stimulated Raman scattering (SRS) technique, are described. A decrease in the energy conversion efficiency and degradation in the beam quality of S1 was observed in pure CH4 at high pump energies. This problem was overcome in CH4:He and CH4:Ar mixtures. Compared with the first Stokes (1.54 μm) energy conversion efficiency in pure CH4, at a pump energy of 126 mJ, an enhancement of 50% in energy conversion efficiency was observed in the CH4:Ar mixture (60% argon concentration) and as much as 100% in the CH4:He mixture (60% helium concentration). The use of these buffer gas mixtures improved the spatial beam quality of the Stokes radiation considerably and also resulted in raising the pump threshold for optical breakdown of the Raman gain medium. 相似文献
5.
使用800nm飞秒脉冲激光研究了Xe,Ar,He等原子团簇对激光的吸收.实验结果表明,脉冲阀门的工作压力、所使用的气体种类等因素对团簇的尺寸及团簇对激光的吸收影响很大.在阀门工作压力为20×105Pa、激光功率密度为1×1015W/cm2的条件下,Xe团簇对激光的吸收高达45%.激光预脉冲的存在会降低原子团簇对激光能量的吸收.离子能量测量结果表明,团簇对激光的高效吸收导致较高离子温度等离子体的生
关键词:
原子团簇
飞秒激光
能量吸收效率
高能离子 相似文献
6.
The deflection of a cw probe laser beam, which occurs in a gas mixture after the absorption of a short laser pump pulse, was experimentally studied inside the irradiated region in order to characterize the generation of photothermal and photoacoustic effects. The time varying component of the probe deflection was detected, and the results are presented as functions of pumping fluences, laser wavelengths and gas pressures. Numerical modelling of the thermo-acoustic dynamics leads to the definition of an effective energy relaxation time for SF6/Ar gas mixtures. An interesting nonlinear behaviour of this energy relaxation time is reported. 相似文献
7.
A. A. I. Khalil M. A. Gondal N. Al-Suliman 《Applied physics. B, Lasers and optics》2011,103(2):441-450
A trace-gas sensor for carbon monoxide based on Pulsed Laser-Induced Photo-Acoustic Spectroscopy (PLIPAS) in conjunction with
laser excitation wavelength of 213 nm was designed, fabricated and tested for the first time. PLIPAS-based sensor with different
cell geometry was employed to enhance the sensitivity down to 58 ppbV level. The parametric dependence of the PLIPAS signals
on CO gas concentration, buffer gas (Ar, O2 and He) concentration, laser pulse energy was studied and Ar proved to be better than O2 and He in terms of enhancing the sensitivity of the system. The signal-to-noise ratio and limit of detection have been quantified
for different experimental conditions. This study proves that PLIPAS-based CO gas sensor is a reliable gas-leak detection
system with high sensitivity and selectivity. Hence this sensor can be employed for pollution monitoring and detection of
CO in a noisy environment. 相似文献
8.
CO2 laser-induced plasma CVD synthesis of diamond 总被引:1,自引:0,他引:1
V.I. Konov A.M. Prokhorov S.A. Uglov A.P. Bolshakov I.A. Leontiev F. Dausinger H. Hügel B. Angstenberger G. Sepold S. Metev 《Applied Physics A: Materials Science & Processing》1998,66(5):575-578
2 laser maintenance of a stationary optical discharge in a gas stream, exhausting over a substrate into the air (laser plasmatron).
Nano- and polycrystalline-diamond films were deposited on tungsten substrates from atmospheric-pressure Xe(Ar):H2:CH4 gas mixtures at flow rates of 2 ?/min. A 2.5-kW CO2 laser focused beam produced plasma. The deposition area was about 1 cm2 and growth rates were up to 30–50 μm/h. Peculiarities and advantages of laser plasmatrons are discussed.
Received: 15 January 1998/Accepted: 16 January 1998 相似文献
9.
N. Okada Y. Katsumura K. Ishigure 《Applied Physics A: Materials Science & Processing》1992,55(2):207-212
Corrosion resistance of carbon steel coated with thin film deposited from Cr(CO)6 using an ArF excimer laser (193 nm) has been evaluated by an electrochemical method as a function of laser beam intensity. The carbon steel coated with the film formed at higher beam intensity shows higher corrosion resistance. Microstructure, composition, and thickness of the films have also been investigated. SEM micrographs show that the films consist of small grains which decrease in size with increasing beam intensity. Auger electron spectroscopy (AES) combined with Ar+ beam sputtering reveals that the films deposited at higher beam intensity give higher chromium content, and that the thickness at a fixed total irradiation energy increases up to the intensity of 10 MW cm–2, falling above this intensity. In addition, the change of film thickness by addition of buffer gases (Ar, CO, and H2O) has been investigated. The thickness is 10 times smaller under the addition of H2O, and twice smaller under the addition of Ar or CO than without the addition of gases. A deposition mechanism based on photolysis of Cr(CO)6 in the gas phase is proposed related to the experimental data after the discussion of several possible mechanisms. 相似文献
10.
J. CiganovicJ. Stasic B. GakovicM. Momcilovic D. MilovanovicM. Bokorov M. Trtica 《Applied Surface Science》2012,258(7):2741-2748
Interaction of a TEA CO2 laser, operating at 10.6 μm wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm2 in the surrounding of air, N2, O2 or He. The energy absorbed from the TEA CO2 laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N2 and O2, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions. 相似文献
11.
A. F. Glova A. Yu. Lysikov D. D. Malyuta S. S. Nelyubin P. I. Peretyatko Yu. F. Ryzhkov 《Physics of Atomic Nuclei》2016,79(14):1663-1670
An experimental installation with a laser plasmatron based on a continuous wave CO2 laser with a radiation power of up to 3.5 kW has been created. The plasmatron design makes it possible to bring out the plasma jet into atmospheric air both along and across the laser beam direction. The spatial temperature distributions on the metal substrate surface heated by the plasma jet are measured. The threshold power for optical discharge maintenance as a function of the gas flow rate and the focal length of the focusing lens are obtained for an Ar and Ar/CH4/H2 gas mixture under atmospheric pressure; the radiation spectrum of the discharge plasma is measured. A one-dimensional model of the discharge for estimation of its geometrical parameters in a convergent laser beam with consideration of radiation refraction on the discharge is given. 相似文献
12.
Characteristics of a Ne-like Ar 46.9-nm soft X-ray laser in capillary discharge at a low Ar pressure
A capillary discharge-pumped Ne-like Ar 46.9-nm soft X-ray laser at a low Ar pressure (28–46 Pa) is proven. To our knowledge, this is the first time an XRD laser output in the condition of the low threshold of a main-current pulse spike (20–21 kA) is demonstrated. The Al2O3 ceramic capillary tube is 20 cm in length (Mo electrode is 4 cm in length) and 3 mm in diameter. The maximum laser energy of the precalibrated XRD is 3.5 μJ. The maximum gain coefficient g = 0.46 cm?1, the maximum gain-length product is 8.28, the beam divergence is 5.4 mrad, and the laser pulse width is 1.65 ns. In addition, the results show that the laser plasma column became difficult to Z-pinch with a increasing Ar pressure, its Z-pinching state of a higher Ar pressure fluctuates more intensely than that of a lower pressure by analyzing the scattering of the delay time between the pre-and main-current pulse. 相似文献
13.
Sheldon S.Q. Wu Thomas F. Soules Scott C. Mitchell Raymond J. Beach 《Optics Communications》2008,281(5):1222-1225
We report a demonstration of a 795-nm rubidium optical resonance transition laser using a buffer gas consisting of pure 3He. This follows our recent demonstration of a hydrocarbon-free 795-nm rubidium resonance laser which used naturally-occurring He as the buffer gas. Using He gas that is isotopically enriched with 3He yields enhanced mixing of the Rb fine-structure levels. This enables efficient lasing at reduced He buffer gas pressure, improved thermal management in high average power Rb lasers and enhanced power scaling potential of such systems. 相似文献
14.
R. Plasil I. Korolov T. Kotrik P. Dohnal G. Bano Z. Donko J. Glosik 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):391-398
Experimental studies of the electron energy distribution function “EEDF” under well defined conditions in flowing afterglow
plasma, using a Langmuir probe are reported. The EEDF is measured in He2
+ and Ar+ dominated plasmas and in XeH+ and XeD+ dominated recombining plasmas. He is used as a buffer gas at medium pressures in all experiments (1600 Pa, 250 K). The deviation
of the measured EEDF from Maxwellian distribution is shown to depend on plasma composition and on the processes governing
the plasma decay. The influence of energetic electrons produced during the plasma decay on the body and tail of the EEDF is
observed. The mechanism of energy balance in afterglow plasma is discussed. 相似文献
15.
G. Tomassetti A. Ritucci A. Reale L. Palladino L. Reale S. V. Kukhlevsky F. Flora L. Mezi J. Kaiser A. Faenov T. Pikuz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):73-77
A capillary discharge soft X-ray laser operating at 46.9 nm on the transition 3p-3s (J = 0-1) of the Ne-like Ar has been realized by exciting the active medium with a long half-cycle duration current pulse of
140 ns. The current is produced by discharging a 10 nF water dielectric capacitor, initially charged to voltages lower than
200 kV by a six stage Marx generator, through a 15-cm long capillary channels. The laser amplification has been obtained by
properly adjusting all the other experimental parameters. Utilizing a 3-mm in diameter Al2O3 capillary channel initially filled with 0.3 torr of Ar pressure, a laser beam, which has a 4-mrad divergence and a time duration
of 1.3 ns, is characterized by a gain of 0.6±0.1 cm-1. The stability of the plasma compression followed by the laser emission is verified.
Received 13 December 2001 相似文献
16.
The results of experimental measurement of spatial-angular distributions of hydrogen particles (H−, H0, H+) obtained in scattering of a collimated ribbon beam of H− ions and H0(1s) atoms in He, Ar, Kr, Xe, H2, O2, and CO2 gas targets for certain values of energy in the range from 0.6 to 15 MeV are reported. The experimental setup and the measurement
procedure with an angular resolution of 5×10−6 rad are described. The angular characteristics of measured distributions, i.e., full width at half maximum and standard deviation,
were determined. It is shown that the shape of distribution for a beam of hydrogen atoms produced by neutralization of H− ions in a gas target varies with the type and thickness of the target, and the angular spread is smallest for the H2 target. The variations in the shape of distribution are due to the contribution of scattering processes without changing
the charge of particles. 相似文献
17.
We have measured the electron energy of the thermal group of electrons in both longitudinal and transverse electron beam created helium glow discharges. The measurement technique employs the ratio of intensities of spectral lines in the 2s3S?np3P He I series. Values of kTe between 0.07 and 0.11 eV were obtained. These energies are typical of the beam-generated electric field free plasmas. The competitive loss of helium ions by recombination and by charge transfer in a He?Hg electron beam created plasma is calculated. The results are applied to the Hg+ laser pumping scheme using a electron beam created He?Hg plasma. 相似文献
18.
本文从实验上研究了不同缓冲气体(He,Ar,N2和Air)中激光Al等离子体的时间分辨发射光谱,研究了原子发射谱线的强度和Stark展宽随延时、缓冲气体性质和压力变化的规律.结果表明原子谱线的强度在3μs左右达到最大值,随着延时的增加,谱线的Stark展宽减小,而缓冲气体压力的增大导致谱线的Stark展宽增大,在实验测定的四种缓冲气体中,Ar气体中谱线的Stark展宽最大. 相似文献
19.
D. Mathew P. J. M. Peters H. M. J. Bastiaens K.-J. Boller 《Applied physics. B, Lasers and optics》2009,95(1):155-159
The effect of addition of xenon on the long term homogeneity of discharges in F2and ArF excimer laser gas mixtures was investigated in a small-volume discharge chamber. The gas mixture in the discharge
chamber was preionized by X-rays. A special electrical excitation circuit containing a pulse forming line provided a long,
square-shaped current pumping pulse of a predetermined duration to the discharge electrodes. The initiation and the development
of the discharge was monitored via its fluorescence signal with an intensified CCD camera. We found that adding Xe up to partial
pressures of 0.53 mbar extended the homogeneous phase of the discharge from 80 ns to approximately 200 ns in He/F2as well as in He/Ar/F2and Ne/Ar/F2excimer laser gas mixtures. Monitoring of the ArF and XeF spontaneous emission signals showed that the formation of ArF excimers
remained unaffected by the addition of xenon (up to 1.3 mbar) to the laser gas mixture. 相似文献
20.
M. R. Berman 《Applied Physics A: Materials Science & Processing》1991,53(5):442-448
Xenon chloride (308 nm) excimer laser-assisted etching of GaAs (100) in Cl2 was demonstrated and characterized with respect to laser and gas parameters. The etch rate increased linearly with laser fluence from thresholds in the range of 50 to 75 mJ/cm2 to the highest fluence studied, 650 mJ/cm2. For a laser fluence of 370 mJ/cm2, the etch rate varied with Cl2 pressure reaching a maximum at a Cl2 pressure of about 2 Torr. The etch rate decreased monotonically with Ar buffer gas pressure because of redeposition of GaCl3 products into the etched channel. The redeposited GaCl3 affected the etch rate and the etch morphology. The etch rate and morphology also varied with laser repetition rate. The mobility of chlorine on the surface also plays an important role in the etching mechanism. 相似文献