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本文叙述用一维非平衡辐射流体力学激光打靶程序模拟计算高功率密度(~1013W/cm2)激光照射中Z介质薄靶形成的等离子体状态。考虑的物理过程有轫致、光电离、电子碰撞电离及它们的逆过程,Compton散射过程等。Compton散射采用Fokker-Planck近似;电子和离子热传导采用限流扩散近拟;光子方程采用多群限流扩散近似;用平均原子模型计算布居数。激光的吸收主要考虑逆轫致吸收。用功率密度分别为5×1013W/cm2和1×1014W/cm2,波长0.53μm,脉宽450ps的激光从两面和单面打se薄靶,模拟计算结果与国外的实验结果[1]一致。 相似文献
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在低真空条件下(5Pa),通过测量脉冲激光烧蚀平面Al靶产生的等离子体辐射谱的时间分辨特征,得到辐射粒子速度的空间分布.在激光脉冲宽度为10ns,烧蚀斑直径为200μm,靶面上功率密度分别为1.91×1010,5.10×1010和7.64×1010W/cm2时,测得辐射粒子Al的速度均在106cm/s量级,且随着靶面径向距离的增大而近似呈指数衰减.在距靶面的相同距离处,激光功率密度的增大反而使速度减小.利用激波模型(shockwave model)较好地解释了实验结果,并得出激波的波面基本为柱对称
关键词:
激光等离子体
平面Al靶
粒子速度分布
激波 相似文献
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非线性一维光子晶体波导光双稳 总被引:2,自引:2,他引:0
利用非线性折射率系数较大且非线性时间响应较快的CdSxSe1-x玻璃为材料,设计并制备了非线性一维光子晶体波导光双稳器件,该器件的折射率空间分布呈正弦形式。实验测得双稳开关的阈值功率密度为1.60×105W/cm2,开关时间为63ps。采用时域有限差分方法讨论了光子晶体带隙随入射光强变化而移动的情况,随着入射光功率密度的增加,光子晶体的带隙中心向短波方向移动。同时计算了该器件的双稳特性,理论计算得到双稳开关的阈值功率密度为1.40×105W/cm2,开关时间约为50ps。获得了理论与实验基本一致的结果。 相似文献
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利用等离子增强化学气相沉积系统制备了本征非晶硅薄膜,并选用488 nm波长的连续激光进行晶化.采用喇曼测试技术对本征非晶硅薄膜在不同激光功率密度和扫描时间下的晶化状态进行了表征,并用514 nm波长与488 nm波长对样品的晶化效果进行了比较.测试结果显示:激光照射时间60 s, 激光功率密度在1.57×105 W/cm2时,能实现非晶硅向多晶硅的转变,在功率密度达到2.7 56×105 W/cm2时,有非晶开始向单晶转变,随着激光功率密度的继续增加,晶化结果仍为单晶;在功率密度为2.362×105 W/cm2下,60 s照射时间晶化效果较好;在功率密度为2.756×105 W/cm2和照射时间为60 s的条件下,用488 nm波长比514 nm波长的激光晶化本征非晶硅薄膜效果较好,并均为单晶态. 相似文献
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A. P. Kuznetsov A. S. Alexandrova O. I. Buzhinsky K. L. Gubskiy T. V. Kazieva A. V. Savchenkov S. N. Tugarinov 《Physics of Atomic Nuclei》2015,78(10):1155-1163
The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 107 W/cm2. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant. 相似文献
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F.O. Adurodija R. Brüning I.O. Asia H. Izumi T. Ishihara H. Yoshioka 《Applied Physics A: Materials Science & Processing》2005,81(5):953-957
The properties of indium tin oxide (ITO) thin films, deposited at room temperature by simultaneous pulsed laser deposition (PLD), and laser irradiation of the substrate are reported. The films were fabricated from different Sn-doped In2O3 pellets at an oxygen pressure of 10 mTorr. During growth, a laser beam with an energy density of 0, 40 or 70 mJ/cm2 was directed at the middle part of the substrate, covering an area of ∼1 cm2. The non-irradiated (0 mJ/cm2) films were amorphous; films irradiated with 40 mJ/cm2 exhibited microcrystalline phases; and polycrystalline ITO films with a strong 〈111〉> preferred orientation was obtained for a laser irradiation density of 70 mJ/cm2. The resistivity, carrier density, and Hall mobility of the ITO films were strongly dependent on the Sn doping concentration and the laser irradiation energy density. The smallest resistivity of ∼1×10-4 Ω cm was achieved for a 5 wt % Sn doped ITO films grown with a substrate irradiation energy density of 70 mJ/cm2. The carrier mobility diminished with increasing Sn doping concentration. Theoretical models show that the decrease in mobility with increasing Sn concentration is due to the scattering of electrons in the films by ionized centers. PACS 81.15.Fg; 73.61.-r; 73.50.-h 相似文献
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L. Torrisi 《辐射效应与固体损伤》2013,168(11-12):811-818
A study of Ti laser irradiation and thin film deposition produced by an Nd:Yag pulsed laser is presented. The laser pulse, 9?ns width, has a power density of the order of 1010?W/cm2. The titanium etching rate is of the order of 1?µg/pulse, it increases with the laser fluence and shows a threshold value at about 30?J/cm2 laser fluence. The angular distribution of ejected atoms (neutrals and ions) is peaked along the normal of the target surface. At high fluence, the fractional ionization of the plasma produced by the laser is of the order of 10%. Time-of-flight measurements demonstrate that the titanium ions, at high laser fluence, may reach kinetic energies of about 1?keV. Obtained results can be employed to produce energetic titanium ions, to produce coverage of thin films of titanium and to realize high adherent titanium-substrate interfaces. The obtained results can be employed to produce energetic titanium ions, to produce a coverage of thin titanium films on polymers, and to realize highly adherent titanium–substrate interfaces. 相似文献
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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
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A. A. Chistyakov I. L. Martynov K. E. Mochalov V. A. Oleinikov K. V. Zaharchenko 《Laser Physics》2008,18(8):925-938
The photophysical properties of solutions and films with relatively high concentrations of CdSe/ZnS nanoparticles are studied in the presence of the visible laser irradiation in a wide range of power densities. The short-wavelength wing detected in the photoluminescence spectra of the solutions of quantum dots is due to the selective laser excitation of small-size nanoparticles. A comprehensive analysis of the anti-Stokes photoluminescence of the nanoparticles in solutions and films indicates the thermal mechanism of this phenomenon. The dimensional quantization effect, narrow spectra, and a relatively high luminescence yield are retained in the films with a high nanoparticle concentration. The luminescence spectra of the films remain unchanged when the laser flux density increases to 1 × 106 W/cm2. The effect of the laser radiation on the nanoparticle films is studied at the flux densities exceeding the damage threshold (5 × 106–1 × 109 W/cm2). 相似文献
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《Surface science》1988,194(3):L105-L111
Thin films of CuAlSe2 have been formed by a laser beam interaction process and analyzed with optical and Auger spectroscopies. It has been found that at low incident power (8.4 W/cm2) of the argon ion laser (all lines) the compound is formed together with another binary such as Cu2Se. As the power increases, the second phase disappears and, at 11.7 W/cm2, reasonably good quality thin films are obtained. It is worth pointing out that the films formed by this technique show defects which need to be eliminated before using them for non-linear optical devices. 相似文献
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P. S. Shkumbatyuk 《Technical Physics》1999,44(10):1250-1252
The influence of the local thermal effect of continuous CO2 laser radiation with a power density as high as 103 W/cm2 on metal-Si films is investigated. It is discovered that the structural defects formed as a result of irradiation influence
the transport of the metal in Si.
Zh. Tekh. Fiz. 69, 135–137 (October 1999) 相似文献
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High power double discharge type TEA CO2 laser was used to study laser plasma interaction on carbon target plasma. The maximum output power was 0.3 GW and full width at half maximum intensity was 100 ns. We measured the reflectivity of the laser light at 10.6 μm in wavelength from the carbon plasma. The reflectivity showed a maximum (≈56%) at the laser power intensity of about 1.1 x 1010 W/cm2, and at above this value, the reflectivity decreased. The absorption was introduced effectively above this intensity. The electron density and temperature were also measured. 相似文献
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A. Mangione L. Torrisi A. Picciotto F. Caridi D. Margarone E. Fazio 《辐射效应与固体损伤》2013,168(10-12):655-662
Plasma laser ablation experiments were performed irradiating glassy-carbon targets placed in vacuum through a pulsed Nd:YAG laser operating at the second harmonic (532 nm), 9 ns pulse width and 109 W/cm2 density power. Thin films of ablated carbon were deposited on silicon oxide substrates placed at different distances and angles with respect to the target. The analysis of the deposited material was carried out by using surface profiler, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and Raman spectroscopy. Results show the evidence of carbon nanocrystals and nanostructures with dimension of the order of 100 nm deposited on the substrates together with a large amount of amorphous phase. The spectroscopic investigations and the SEM images indicate the formation of nanodiamond seeds as a nucleation process induced on the substrate surface. Nanostructures were investigated as a function of the laser intensity and angle distribution. Experimental results were compared with the literature data coming from nanodiamonds growth with different techniques. Experiments performed at Instituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS) of Catania (Italy) and data analysis conducted at Dipartimento di Fisica and DFMTA of the Università of Messina (Italy), CNR-ITIS of Messina and ST-Microelectronics of Catania will be presented and discussed. 相似文献