共查询到18条相似文献,搜索用时 146 毫秒
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为了验证理论分析得到的圆锥形喷管在单脉冲条件下的激光推进能量相似律,用2维轴对称辐射流体动力学方法,计算得到了不同构形的推进性能参数,分析了锥角、长度、无量纲因子、入射激光能量对冲量、冲量耦合系数的影响。计算揭示的激光推进能量相似律合理,在理论模型可以描述的范围内,其定性规律与理论分析、实验结果之间相互印证。结果表明:当锥角固定时,冲量和冲量耦合系数随无量纲因子先增大后减小,极大值对应的无量纲因子仅与气体比热比相关;当无量纲因子固定时,冲量随入射激光能量增加而增大,冲量耦合系数受激光能量的影响很小,冲量和冲量耦合系数均随锥角增大而单调减小。 相似文献
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为结合金属高比冲和聚合物工质高冲量耦合系数的优点,为激光推进光船优选工质,对掺入金属粉末的聚甲醛(POM)工质在CO2激光辐照下的推进性能开展了实验研究。结果表明:在一定的条件下金属粉末能提高工质的推进性能。掺入微米铝粉的聚甲醛工质的冲量耦合系数最大值由12×-5 N/W提高到21.72×10-5 N/W,在直筒结构的约束下,最高冲量耦合系数和比冲分别提高到61.64×-5 N/W和727.32 s,能量利用率超过了100%,表明工质参与了化学反应。 相似文献
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设计了触发间隔从100 ms到5 ms可调的双脉冲触发器驱动TEA CO2激光器高压开关,用以模拟激光器不同的输出脉冲重复频率。用该装置精确控制的不同激光脉冲重复频率下,对抛物面型光船模型进行了大气模式激光推进中冲量耦合系数的实验研究。发现冲量耦合系数随着重复频率的增加而下降,而单位时间内光船获得的冲量耦合系数的增量则随着重复频率的增加而增大。初步分析认为,这是由于飞行器内的空气未得到充分的补充造成的。 相似文献
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利用透镜聚焦,抛物面喷管约束,结合复摆和光指针测量系统研究了单脉冲能量对吸气式激光推进冲量耦合系数的影响,实验中通过调节激光器工作电压和硅片衰减实现了脉冲能量5~70 J范围的有效拓展;进一步采用纳秒分幅高速相机拍摄了24 J能量下的流场纹影照片。结果表明:在4~9 J低能量和32~70 J较高能量区间,冲量耦合系数均较稳定;9~32 J能量下冲量耦合系数呈线性增长趋势,变化范围(6.5~21.0)×10-5 N·s·J-1;纹影照片显示流场演化经历了激光支持爆轰波、爆燃波和激波3个阶段,耦合系数的变化规律源于不同单脉冲能量对应不同的能量沉积效率。 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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采用单脉冲激光进行了大气环境下激光烧蚀小钢珠实验,得到其推进效应参数,发现并分析了钢珠在不同放置位置(焦前与焦后)时不同的物理现象;为了得到一系列定量实验数据,采用自行研制的激光冲量靶仪进行了单脉冲激光烧蚀推进效应实验测试,得到了不同环境条件、不同靶材料的激光推进效应参数,并与国外的实验数据以及数值计算结果进行了比较。实验表明,靶材料和激光功率密度是影响冲量耦合系数的主要因素,冲量耦合系数随环境气压的降低而升高。 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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为研究激光烧蚀靶产生冲量过程和机理, 建立了一个复杂的一维热传导和流体动力学模型. 以空间碎片常见材料Al为例, 用建立的模型数值计算了纳秒脉宽激光烧蚀靶产生的冲量及冲量耦合系数随时间变化情况. 数值结果和已有的实验数据符合的较好. 数值计算表明: 激光脉冲时间内, 靶获得的冲量随时间迅速增加, 在脉冲时间结束后, 冲量变化随时间趋于稳定; 在冲量耦合过程中, 烧蚀等离子体向真空膨胀, 羽流尺度逐渐增大, 同时吸收入射激光能量, 导致激光与靶耦合的能量降低.
关键词:
激光烧蚀
冲量耦合
等离子体 相似文献
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Thrust enhancement via gel-type liquid confinement of laser ablation of solid metal propellant 总被引:1,自引:0,他引:1
Soojin Choi Tae-hee Han Ardian B. Gojani Jack J. Yoh 《Applied Physics A: Materials Science & Processing》2010,98(1):147-151
Laser propulsion has been developed as a suitable small thruster technology for the attitude control of micro and nano class
satellites. Laser-based thrusters meet the satellite design criteria for being of light weight and cost effective, because
they do not require fuel storing and oxidizer for combustion. Also, thrust control by laser propulsion is achieved fairly
easy. In this paper, we consider the confinement of plasma expansion by a gel-type liquid material, which results in the enhancement
of the thrust for propulsion. We also present our attempts to resolve some known issues regarding laser ablation of solid
and liquid targets. The level of thrust is quantified via the momentum coupling coefficient, which was experimentally measured
using a ballistic pendulum system. We have discovered that the laser ablation confinement by the gel-type medium results in
2.3 times more enhanced driving force as compared to the water confinement. A proof of performance is demonstrated for using
gel-type material for generating propulsion, and material characterization for optimal thrust performance is presented. 相似文献
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Ablative laser propulsion (ALP) could revolutionize space travel by reducing the 30:1 propellant/payload ratio needed for near-earth orbit 50-fold. Experiments to date have demonstrated the necessary efficiency, coupling coefficient, and specific impulse for application, but were performed at pulse energies and spot sizes much smaller than required and at wavelengths not usable in the atmosphere. Prior experiments have also not simultaneously measured the properties of the ions produced or of the ablated surface, properties that would allow full understanding of the propulsion properties in terms of ion characteristics. The first realistic measurements of laser propulsion parameters are proposed using PALS (Prague Asterix Laser System), the important parameters of which (pulse energy (~ 1 kJ), pulse length (400 ps), beam diameter (~ 29 cm), and flat beam profile) equal those required for application. The PALS wavelength is a little short (1.3 μ m vs.>1.5 μ m) but is closer than any other laser available and PALS’ 2ω/3ω capability should allow extrapolation to application values. The PALS’ proven infrastructure for measuring laser-driven ion properties means that only a ballistic pendulum for measuring momentum transfer will have to be added. 相似文献
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Carlos A. Rinaldi Norberto G. Boggio Daniel Rodriguez Alberto LamagnaAlfredo Boselli Francisco ManzanoJorge Codnia M. Laura Azcárate 《Applied Surface Science》2011,257(6):2019-2023
Propulsion pellets of different metal/salt (Zn/CaCO3) composition have been prepared. The impulse imparted to the pellet by the laser has been measured using two different methods: a torsion pendulum and a piezoelectric sensor. The dependence of the coupling coefficient, Cm, on the composition of the solid binary propellants in ablative laser propulsion has been investigated under different experimental conditions: in vacuum and at atmospheric pressure as well as with two different wavelengths, IR and UV. The composition of the Zn/CaCO3 propellant mixture that optimizes the coupling coefficient, Cm, has been determined. 相似文献
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In order to investigate the mechanisms of both the air-breathing and the ablation modes of laser propulsion under laboratory conditions, a multi-use laser impulse pendulum (MULIP) is developed. The measurable impulse range is from 1.0×10-4 to 3.8×10-3 N.s. The experimental calibration data agree well with the theoretical calculated data. With MULIP, the ablation mode has been performed, in which a high power pulsed Nd:glass laser (λ= 1.06μm,Τ= 20 ns) and a gray PVC film sample are used. The experimental results show that the maximum momentum coupling coefficient Cm is 7.73×10-5 N/W, and the maximum specific impulse Isp is 208.6 s. 相似文献
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采用YJG-Ⅱ激光微区分析仪、组合式多功能光栅光谱仪和CCD数据采集处理系统构成的激光微等离子体光谱分析系统,以国家标准土壤样品(BGW07411)为样品,在Ar,He和不同He-Ar混合的环境气氛下,以Ca Ⅱ 393.367 nm,Ca Ⅱ 396.847 nm为分析线,实验研究了土壤激光微等离子体辐射强度.研究结果表明,He-Ar混合气氛环境等离子体发光时间、辐射强度均好于单一He,Ar环境气氛.当He-Ar混合气体分别为:He 66.7%,Ar 33.3%时,等离子体辐射强度明显增强,并在此条件下研究了辅助电极高度对激光微等离子体辐射强度的影响.当辅助电极高度为3 nm时,激光微等离子体的辐射强度达到最佳. 相似文献
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微空心阴极放电推力器是一种新颖的电热式微推力器,利用纳卫星提供的1~10 W的功率可提高微推进装置的性能。为了预示该推力器的性能,结合实验中测量的气体温度值和火箭发动机原理,初步计算得出微放电推力器的推力范围为几十至上千μN,以氩气为工质比冲量级为600~1 000 N.s/kg,以氦气为工质比冲量级为3 000 N.s/kg。研究结果表明,微空心阴极放电较小的尺寸结构与强烈并可控的气体加热相结合,可以开发应用在电热式微放电推进中,作为微小卫星,尤其是纳卫星和皮卫星的动力系统。 相似文献
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利用基于SOS的SPG200高压脉冲功率装置研究了有机玻璃(PMMA)和尼龙1010在变压器油中的闪络特性。研究结果表明:闪络电压随内电极直径增加近似指数增加,随闪络距离延长近似线性增加,相应的击穿时延也近似线性增加。受实验条件的影响,有机玻璃和尼龙1010的闪络性能略有差异。同轴径向电场降落集中在内电极表面附近一定径向距离内,同轴电场下的闪络电压主要由内电极表面电场与径向电场分布的均匀程度决定。增加内电极直径和延长闪络距离都可以提高闪络电压,而增加内电极直径的效果更显著。 相似文献