飞秒激光驱动X射线源中超热电子与靶相互作用研究

飞秒激光与靶相互作用产生超热电子,随后超热电子与靶原子碰撞,通过kα、kβ等散射过程,可辐射高亮度、飞秒级X射线,在原子与分子物理、生物及医学等领域均有广泛的应用前景.论文首先对飞秒激光驱动X射线源的发展进行简要叙述,然后对X射线源中的超热电子与靶相互作用进行研究.超热电子的产生由靶材对光脉冲的非碰撞吸收机制决定,X射线的产生由超热电子决定.研究超热电子、靶参数对X射线产额的影响,确定最佳参数值,可指导驱动激光脉冲参数的选择,以获得更大的X射线光子产额.使用蒙特卡洛模拟方法可研究超热电子动能及入射角、靶材(Cu靶)厚度对靶材上、下表面X射线辐射光子产额的影响,分析确定最佳超热电子动能及最佳靶厚.驱动激光强度与超热电子动能的定标关系表明：需要合理选择驱动激光参数,使真空加热机制主导超热电子产生过程,以在合适的激光脉冲强度下获得最大X射线光子产额.     

Electroluminescence Caused by the Transport of Interacting Electrons through Parallel Quantum Dots in a Photon Cavity

We show that a Rabi‐splitting of the states of strongly interacting electrons in parallel quantum dots embedded in a short quantum wire placed in a photon cavity can be produced by either the para‐ or the dia‐magnetic electron‐photon interactions when the geometry of the system is properly accounted for and the photon field is tuned close to a resonance with the electron system. We use these two resonances to explore the electroluminescence caused by the transport of electrons through the one‐ and two‐electron ground states of the system and their corresponding conventional and vacuum electroluminescense as the central system is opened up by coupling it to external leads acting as electron reservoirs. Our analysis indicates that high‐order electron‐photon processes are necessary to adequately construct the cavity‐photon dressed electron states needed to describe both types of electroluminescence.     

电子束在材料中的能量沉积和热激波特性

采用解析法、矩方法和Monte Carlo法等方法,计算了电子束在硬铝靶材中的能量沉积.计算表明,3个结果基本符合.根据得出的能量沉积结果和一维应变弹塑性流体动力学模型,计算了电子束热激波在硬铝靶材中的传播,并将其应力峰值的计算值与实测值进行了比较.     

Losses in the Energy of Low-Energy Electrons in Fluorene, Fluorenone, and Diiodofluorenone Vapors

Electron energy loss spectra (EELS) of fluorene, fluorenone, and diiodofluorenone vapors excited by monokinetic electrons of energies 15–50 eV have been obtained. The singlet and triplet absorption bands of these molecules have been calculated. Comparison of these bands with the experimental EELSs and optical absorption spectra has shown that the forbiddenness of singlet-triplet transitions is not completely removed in the process of interaction of molecules with electrons. The presence of heavy iodine atoms in the diiodofluorenone molecule enhances singlet-triplet transitions. Bands of overtones of stretching vibrations of the CH groups of the benzene rings have been detected near the peak of elastic scattering of electrons of the molecules studied.     

D-3He先进燃料靶惯性约束聚变的燃耗和增益

计算了球形均匀D-3He先进燃料靶惯性约束聚变(ICF)的燃耗和增益。讨论了这种堆系统的能量平 衡。设计了一种新型的由毛细管阵列组成具有抗辐射损伤、可自动更新的液态金属锂自由表面多孔湿壁,用它取 出聚变能。同时与D-T热核燃料靶系统的燃耗和增益及它们不同的堆工程特性作了比较。     

氢气比例和点火能量对CH4-H2混合气体爆炸强度影响的实验研究

在20 L标准球形爆炸罐内开展了当量比为1的甲烷-氢气-空气混合气体爆炸实验,通过改变点火能量和氢气体积分数,探讨点火能量和气体比例对其爆炸压力和爆炸强度的影响。研究发现:氢气比例越高,爆炸冲击波传播速度越快,点火能对冲击波传播速度的影响相对较小;点火能量的提高对峰值超压有增强作用,氢气比例低时,此增强作用较显著,氢气比例高时,此增强作用较弱;点火能量对爆炸强度指数KG的影响较小,而氢气比例对爆炸强度指数KG的影响十分明显,氢气比例低于50%时,氢气比例的增加对爆炸强度的增强作用较弱,氢气比例高于50%时,氢气的增加对爆炸强度的激励作用急剧增强。另外发现,相同当量比条件下,氢气的爆炸强度指数近似为甲烷爆炸强度指数的10倍。     

Electrons in the Field of Interfering Laser Pulses with Tilted Fronts: Formation of Compressed Bunches and Their Application for the Generation of Coherent γ – Rays

Simulations show that optical traps for charged particles can be formed in the fields of intense ultrashort laser pulses with tilted amplitude fronts. The traps travel in space with the velocities close to the speed of light and can be used for the creation of electron bunches which, at the laser intensities which are currently attainable, are compressed to proportions far below the laser wavelength and have energies reaching hundreds of GeV per particle. If an additional ultrashort laser pulse is propagated in the direction opposite to that of the bunch motion and interacts with the electrons, inverse Compton scattering occurs, with most of the electron energy being transferred to the resulting gamma‐quanta. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Increased Accuracy of the Binding Energy of K- and L-Subshell Electrons in Krypton from Re-analysis of Experimental Data: Importance for Determination of the Neutrino Mass

Analyzing thoroughly K and L X-ray transition energies, results of the former L-shell photoabsorption study and M subshell binding energies from photoelectron and optical spectroscopy, we determined the following electron binding energies in gaseous krypton: 14 327.26(4) eV for the K-shell and 1 921.4(3), 1 731.91(3) and 1 679.21(3) eV for L₁-, L₂-, and L₃-subshells, respectively. These accurate values of electron binding energies are important for energy calibration of the next generation tritium -decay experiment KATRIN with sub-eV sensitivity for the electron-neutrino mass.