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61.
An experiment on a transient nickel-like Mo x-ray laser in the extreme light Ⅲ (XL Ⅲ) laser facility is analyzed, based on the two-dimensional hydrodynamic evolutions of a plasma under a non-uniform incident laser. Influences of the pulse duration and intensity on plasma scale length, electron density, temperature, as well as their distributions are investigated, based on which the pre-pulse character and delay time are determined according to the parameters of laser line focus on XLⅢ. It is found that the optimal intensity of the pre-pulse is 1.0 TW/cm^2 with a duration of 500ps; a well modified pre-plasma can be obtained after 1.6ns under low quality line focus in the lab. 相似文献
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可变入射距离平焦场谱仪的概念设计 总被引:3,自引:3,他引:0
从理论上证明了可变入射距离的平焦场软X射线谱仪设计的可行性。对于标称栅距σ0=(1/1200)mm和象差修正项M20=-20/R, R分别为5649和6000mm的光栅, 对不同的入射距离, 计算出与平焦场相对应的入射角和成象距离, 使一定波长范围内的光谱可以被聚焦在一个平面上,从而提高了变栅距光栅使用的灵活性。同时可通过取消谱仪中入射狭缝, 使谱仪的光通量提高约1个量级。 相似文献
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超短超强激光通过尾波场加速产生的高能负电子束与金属靶相互作用可以获得高能正电子束。实验和计算均表明当高能负电子与较厚的靶相互作用时,产生的正负电子和X射线强度强、发散角大。针对这种情况,为了准确测量能谱,谱仪前方必须使用准直孔,让混合束通过准直孔后再进入大间隙的磁场区域内进行偏转和探测。应用FLUKA程序模拟表明,通过在谱仪外部添加准直孔,谱仪内部添加塑料(以下简称CH)屏蔽片的方式,可以实现谱仪能量分辨率的提高和对噪声的有效抑制,从而实现在混合场中对正电子束能谱进行更准确的诊断。 相似文献
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在中国科学院物理研究所"极光Ⅱ 号"飞秒激光装置上,对激光与薄膜靶相互作用产生的靶后质子束特性进行了实验研究.结果发现,在主脉冲前存在较强的飞秒预脉冲的情况下,通过适当地对激光束散焦,可以使质子束的转换效率提高3 个数量级,并同时改善质子束的准直性.分析表明,激光散焦的方法可以有效地抑制预脉冲的流体力学效应对质子加速的负面影响,从而提高质子的转换效率.此外,粒子模拟还发现,散焦量增大时可以产生更多的中低能超热电子,这也有利于建立高质量的质子加速电场.
关键词:
超短脉冲激光与等离子体相互作用
质子加速
转换效率 相似文献
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The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics(QED) method, which is a non-perturbative theory for the interaction between a plane electromagnetic field and a charged particle. In order to analyze in the real experimental condition, a Lorentz transformation for the cross section of this process is derived between the laboratory frame and the initial rest frame of electrons. The energy of the scattered photon is analyzed, as well as the cross sections for different laser intensities and polarizations and different electron velocities. The angular distribution of the emitted photon is investigated in a special velocity of the electron, in which for a fixed number of absorbed photons, the electron energy will not change after the scattering in the lab frame.We obtain the conclusion that higher laser intensities suppress few-laser-photon absorption and enhance more-laser-photon absorption. A comparison between different polarizations is also made, and we find that the linearly polarized laser is more suitable to generate nonlinear Compton scattering. 相似文献
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在随气泡顶端运动的坐标系中, 通过将理想流体模型推广到非理想流体的情况, 研究了流体黏性和表面张力对Rayleigh-Taylor (RT)和Richtmyer-Meshkov (RM)不稳定性气泡速度的影响. 首先得到了RT和RM不稳定性气泡运动的控制方程 (自洽的微分方程组); 其次给出了二维平面坐标和三维柱坐标中气泡速度的数值解和渐近解, 并定量分析了流体黏性和表面张力对RT和RM气泡速度和振幅的影响. 结果表明: 从线性阶段到非线性阶段的全过程中, 非理想流体中的气泡速度和振幅小于理想流体中的气泡速度和振幅. 也就是说, 流体黏性和表面张力对RT和RM不稳定性的发展都具有致稳作用.
关键词:
Rayleigh-Taylor不稳定性
Richtmyer-Meshkov不稳定性
气泡速度
非理想流体 相似文献