共查询到20条相似文献,搜索用时 140 毫秒
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以水为冷却介质,采用Spray公司的TG0.3机械雾化实心圆锥喷嘴,在体积通量为0.044,0.049和0.053 m3/(m2·s)情况下,对刻有不同微结构槽道冷却面的无沸腾区换热性能进行实验研究。结果表明:刻有微结构的表面可明显增强换热效果;壁面刻有高为0.2 mm的微结构槽道且壁面温度为52 ℃时,体积通量为0.044 m3/(m2·s则热流可达260 W/cm2,通量为0.053 m3/(m2·s则散热功率高达376 W/cm2,完全可以满足当前高功率激光器的散热需求。对于光滑面以及槽肋高为0.1和0.2 mm的换热面,其换热能力随着体积通量的增加而增强;换热面高度为0.4 mm时,通量对换热的影响变得较微弱。微结构槽道不仅增加了换热面积,还有利于液膜扩散,减小液膜厚度,增强换热。在三种不同的流量通量下,高度为0.2 mm的微结构槽道换热性能最佳。 相似文献
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研究了电子通量对ZnO/K2SiO3热控涂层光学性能的影响。分别采用通量为5×1011/cm2·s,8×1011/cm2·s,1×1012/cm2·s 和5×1012/cm2·s的电子对试样进行辐照。电子辐照下涂层的光学性能发生了退化,并且发现了退化涂层在空气中的“漂白”现象。分析了ZnO/K2SiO3热控涂层光学性能的退化机制,同时讨论了电子通量对太阳光谱吸收系数的影响。实验结果发现,在5×1011~1×1012/cm2·s的电子通量范围内,电子通量对ZnO/K2SiO3热控涂层光学性能的影响相同。因此在这个电子通量范围内,采用加速地面试验来模拟空间的电子辐照效应是有效的。 相似文献
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本文引入与浓度和厚度有关的kNL待定参数, 在J-O理论基础上, 对Er3+/Yb3+掺杂的LiNbO3和LiTaO3单晶衬底上 的多晶水热外延样品进行了基于吸收光谱的拟合计算. LiNbO3:Ω2=2.34× 10-20 cm2, Ω4=0.77× 10-20 cm2, Ω6=0.31×10-20 cm2, kNL=4.32× 10-2 mol·m-2. LiTaO3:Ω2=1.68×10-20 cm2, Ω4=0.84×10-20 cm2, Ω6=0.45×10-20 cm2, kNL=9.17×10-3 mol· m-2. 该方法可尝试推广到粉体或胶体等难以直接获得浓度和厚度数据的体系. 经上转换发光测试及光谱参数计分析认为Er3+/Yb3+离子的掺杂浓度比为1:1的情况下, 样品呈现绿色上转换发光光谱; 可尝试以降低基质声子能量的方法提高4I13/2能级 对2H11/2和4S3/2能级的量子剪裁效率. 相似文献
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建立了内靶对兰州冷却储存环主环束流影响的单粒子跟踪模拟程序,对pellet小丸靶和碳靶对束流带来的负面影响进行了模拟研究,主要讨论CSRm内靶实验中的束流存活率和束流寿命状态。结果显示利用厚度为1×1016 atoms×cm-2小丸内靶时,2.6 GeV质子束流寿命在100 s量级,而对于目前技术水平下的碳膜靶 (厚度为 5×1017 atoms×cm-2),质子束流寿命为s量级;束流寿命和束流能量基本成正比关系,束流寿命和内靶厚度近似成反比关系。 相似文献
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本文在20°—300°K研究了室温载流子浓度2×1012—1×1020cm-3含硼或磷(砷)Si的电学性质。对一些p-Si样品用弱场横向磁阻法及杂质激活能法进行了补偿度的测定,并进行了比较。从霍尔系数与温度关系的分析指出,对于较纯样品,硼受主能级的电离能为0.045eV,磷施主能级为0.045eV,在载流子浓度为1018—1019cm-3时发现了费米简并,对载流子浓度为2×1017—1×1018cm-3的p-Si及5×1017—4×1018cm-3的n-Si观察到了杂质电导行为。从霍尔系数与电导率计算了非本征的霍尔迁移率。在100°—300°K间,晶格散射迁移率μ满足关系式AT-a,其中A=2.1×109,α=2.7(对空穴);或A=1.2×108,α=2.0(对电子)。另外,根据我们的材料(载流子浓度在5×1011—5×1020cm-3间),分别建立了一条电阻率与载流子浓度及电阻率与迁移率的关系曲线,以提供制备材料时参考之用。 相似文献
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对Cl/HN3/I2产生NCl(a)/I激光的过程进行了化学动力学计算,主要考察了Cl,HN3和I2的初始粒子数密度及其配比对小信号增益系数的影响。结果发现,当温度为400K, 初始Cl粒子数密度为1×1015,1×1016和1×1017cm-3时,小信号增益系数分别达到1.6×10-4,1.1×10-3和1.1×10-2cm-1,获得最佳小信号增益系数的HN3和I2的初始粒子数密度分别为初始Cl粒子数密度的1~2倍和2%~4%。同时,对Cl,HN3和I2配比对小信号增益系数和增益持续时间的影响进行了讨论。 相似文献
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为了准确诊断真空中微波等离子体喷流的电子数密度,利用统一的发射和单郎缪尔探针测量等离子体的空间电位,再测量等离子体的电流-电压特性曲线.根据空间电位测量结果,在等离子体的电流-电压特性曲线上能准确地获取饱和电流,从而处理出电子数密度.最后的诊断实验表明,当真空环境压强为2—6 Pa、等离子体发生器以60 W以下的微波功率击穿流量范围是42—106 mg/s的氩气时,所产生的微波等离子体喷流中电子数密度分布在1×1016—7.2×1016/m3范围内. 相似文献
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保持CO2激光的单脉冲能量为61.4~64.6 J,采用高精度冲击摆系统进行了不同气压下吸气模式激光推进冲量耦合系数的实验测试,分析了对应的高度特性。结果表明:气压为2.8×104~1×105 Pa,即距离地面0~10 km时,冲量耦合系数大约3.5×10-4 N·s·J-1,上下波动幅度低于5%;气压低于2.8×104 Pa,即高度大于10 km时,冲量耦合系数呈二次曲线显著下降;当气压降至1×103 Pa,即距离地面约31 km高度时,耦合系数仅为9.7×10-5 N·s·J-1。 相似文献
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The thermal effects of the diode end-pumped Nd:YVO4 slab laser crystal are investigated both analytically and numerically. The theoretical model is established with considering the divergence of the pump beam in the slab. A detailed theoretical analysis of the temperature, stress and the focal length of thermal lens are presented. Using 3D finite element analysis, an accurate numerical solution based on the theoretical model is achieved. Our analysis includes the thermal fracture damage of the thermally and optically anisotropic slab and the predicated values are compared with the experimental results. 相似文献
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A method of measuring optical phase differences caused by the presence of optical path differences between two coherent light beams is reported. A polarization technique is used and the phase differences are detected as rotation angles of the plane of polarization. The sensitivity of the method is better than 10-4λ and the stability is 3 X 10-4λ per minute. These limitations result from thermal fluctuations of the order of 10-3°C. A higher sensitivity of about 10-5λ, or better, is expected if the effect due to thermal fluctuations can be reduced. 相似文献
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The X-band ( x ; 9.4 v GHz) electron spin resonance (ESR) spectra of the un-doped isotopically enriched lithium tetraborate (LTB) Li 2 B 4 O 7 single crystals, irradiated by thermal neutrons (fluences | n =2.74 ‐ 10 15 1 1.79 v ‐ 10 18 v cm m 2 ) were investigated at 300 and 77 v K. The LTB crystals of high chemical purity and optical quality with different isotope compositions ( 6 Li 2 10 B 4 O 7 , 6 Li 2 11 B 4 O 7 , 7 Li 2 10 B 4 O 7 and 7 Li 2 11 B 4 O 7 ) were grown by Czochralski technique. The thermal neutrons (the total quantity >90%) with fluence near 10 18 v cm m 2 induce at least 4 different types of stable paramagnetic centers in the Li and B isotopically enriched LTB crystals. The ESR spectra, electron structure and efficiency of generation for centers, induced by thermal neutrons, essentially depend on neutron fluence and isotope composition of the LTB crystals. The local symmetry and the spin Hamiltonian parameters of the observed paramagnetic centers were determined and their electron structure were established. The possible models and formation mechanism of the radiation defects, induced by thermal neutrons in the LTB lattice, are proposed. 相似文献
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A femtosecond mode-locked laser is used for what is believed to be the first time as a broadband infrared source for high-resolution Fourier transform absorption spectroscopy. A demonstration is made with a Cr(4+):YAG laser. The entire nu(1)+nu(3) vibration-rotation band region of acetylene, observed after passing through a single-pass 80-cm-long cell, is simultaneously recorded between 1480 and 1600 nm, in 7.9 s with a signal-to-noise ratio equal to 1000. Two hot bands of the most abundant acetylene isotopologue and the nu(1)+nu(3) band of the (13)C(12)CH(2) are also present. Replacement of the usual conventional tungsten lamp by the bright laser source reduces by about a factor of 150 the recording time needed to get similar results. The noise equivalent absorption coefficient at 1 s averaging is equal to 7x10(-7) cm(-1)Hz(-1/2) per spectral element. 相似文献
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测试了铋酸盐玻璃(85-x)Bi2O3-(10+x)B2O3-5Na2O(x=0,5,10,15,20,25 mol%)中Er3+离子的吸收光谱、荧光光谱、荧光寿命及热稳定性.应用Judd-Ofelt理论计算了铋酸盐玻璃中Er3+离子的强度参数(Ω2=(352—386)×10-20cm2,Ω4=(138—152)×10-20cm2,Ω6=(093—117)×10-20cm2),应用McCumber理论计算了Er3+离子的受激发射截面(σe=(70—95)×10-21cm2)及Er3+离子4I13/2→4I15/2发射谱的荧光半高宽(FWHM=57—79nm),测得了Er3+离子4I13/2能级荧光寿命(τm=265—159ms),分析了玻璃的热稳定性能.研究了Er3+离子各种光谱参数对成分的依赖性,发现随着玻璃中B2O3含量的增加,强度参数Ωt(t=2,4,6)、荧光半高宽(FWHM)、热稳定性均相应增加,而测得的荧光寿命却减小.比较了不同基质玻璃中Er3+离子的光谱特性,结果表明掺铒铋酸盐玻璃更适合于掺Er3+光纤放大器实现宽带和高增益放大.
关键词:
铋酸盐玻璃
光谱性质
成分依赖性
Er3+离子 相似文献
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K-Rb混合蒸汽中,使用Rb光谱灯和染料激光器,将基态Rb原子二步激发到7^2D态用荧光法测量了过程Rb(7^2D)+K(4S)→Rb(5S)+K(7S,5D),的碰撞转移截面,K7S,5D对Rb7^2D的荧光比中,含K7S^←→5D碰撞转移的影响,第二个实验可以消除这个影响,利用K光谱灯和染料激光器产生K7S或5D态,探测K7S(5D)对5D(7S)的荧光比,Rb7D→K7S,5D碰撞转移截面( 相似文献
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Optical measurement of acoustic pressure amplitudes-at the sensitivity limits of Rayleigh scattering
Rayleigh scattering is a measurement technique applicable for the determination of density distributions in various technical or natural flows. The current sensitivity limits of the Rayleigh scattering technique were investigated experimentally. It is shown that it is possible to measure density oscillations caused by acoustic pressure oscillations noninvasively and directly. Acoustical standing waves in a rectangular duct were investigated using Rayleigh scattering and compared to microphone measurements. The comparison showed a sensitivity of the Rayleigh scattering technique of 75 Pa (7·10(-4) kg/m(3)) and a precision of 14 Pa (1·10(-4) kg/m(3)). Therefore, it was also shown that Rayleigh scattering is applicable for acoustic measurements. 相似文献
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用稀土氧化物硫化法合成了固溶体发光材料(Y0.9Gd0.1)2O2S:Tb和(Gd0.9La0.1)2O2S:Tb,并且用阴极射线和254nm紫外线两种激发方式测试了它们的发光性能.研究了固溶体(Y0.9Gd0.1)2O2S:Tb和(Gd0.9La0.1)2O2S:Tb中Tb3+离子5D3——7FJ和5D4——7FJ的能级跃迁强度随Tb3+离子浓度而变化的关系,以及它们的发光色度随激活剂Tb3+离子浓度的变化,探讨了Tb3+离子的浓度猝灭机理. 相似文献