滞后型脉冲泛函微分方程周期解的存在性

本文借助Mawhin重合度理论中的延拓定理和广义常微分方程周期解的存在性,在滞后型脉冲泛函微分方程与广义常微分方程存在等价关系的条件下,建立了滞后型脉冲泛函微分方程周期解的存在性定理.     

KLi(HC3N3O3)·2H2O晶体的电光效应和生长研究

本文采用电光系数的粉末测试方法，探索发现了新型电光晶体KLi(HC₃N₃O₃)·2H₂O。根据粉末样品的红外反射光谱和拉曼光谱，计算获得晶格振动对电光系数的贡献值，再加上粉末倍频效应推算的有效非线性光学系数，最终计算出KLi(HC₃N₃O₃)·2H₂O的电光系数为2.37 pm/V,与商用电光晶体β-BBO相当。采用水溶液法进行晶体生长，测试不同原料生长晶体时的过热和过冷曲线，优化生长工艺，获得35 mm×25 mm×10 mm透明晶体。采用X射线定向技术辅以压电系数测量，确定了晶体形貌与各向异性生长速率的对应关系。     

Determination of bulk viscosity of liquid water via pulse duration measurements in stimulated Brillouin scattering

We present a method by which to determine the bulk viscosity of water from pulse duration measurements of stimulated Brillouin scattering （SBS）. Beginning from a common model of Brillouin scattering, the bulk viscosity is shown to play an important role in Brillouin linewidth determination. Pulse durations of SBS back-reflected optical pulses are measured over the temperature range of 5-40℃. SBS linewidths are de- termined via Fourier transformation of the time-domain results, and the bulk viscosity of water is measured and derived from the obtained values. Our results show that the proposed method for measurement of pulse durations is an effective approach for determining bulk viscosity. The method can be easily extended to determine bulk viscosities of other Newtonian liquids.     

Extended breakdown of Simpleman approximation

In this letter, we solve three-dimensional time-dependent Newton equations for atoms interacting with a ten-cycle elliptically polarized laser pulse. The ionized electron momentum distributions show a tilt angle between the distribution density peak and the main polarization axis. The tilt angle’s behavior changes with an increasing laser intensity. We show that this behavior change is directly related to the release time of the electron from the atom.     

Switchable Q-switched and laser operating mode-locked erbium-doped fiber in the L-band region

We demonstrate a switchable Q-switched and mode-locked erbium-doped fiber laser （EDFL） operating in the L-band region using the nonlinear polarization rotation effect. The switching operation is achieved by controlling intensity-dependent loss using a polarization controller. In Q-switching mode, the EDFL produces a pulse train with a repetition rate of 21.1 kHz, pulse width of 7.7 #s, and pulse energy of 13.6 nJ. The EDFL also generates a multi-wavelength comb with a very narrow and constant wavelength spacing of 0.045 nm and optical signal-to-noise ratio of at least l0 dB. During mode locking, the EDFL produces stretched pulses with 3-dB bandwidth of 26.2 nm, pulse width of 350 fs, repetition rate of 2.38 MHz, and pulse energy of 48.56 pJ.     

Investigations of ionization-induced injection of laser wake field acceleration using phenomenological model

We develop a phenomenological model to investigate dynamics of ionization-induced injection. In the ＂bubble＂ regime of laser wakefield acceleration （LWFA）, it is found that there is an upper limit for laser intensity of ionization-induced injection. In the plane perpendicular to the laser polarization, when the laser pulse is linearly polarized, ionization-induced injected electrons exhibit a filamented structure and semi-coherent betatron oscillation.     

金属管内光环现象的观察与研究

对于内壁光滑的圆柱状金属管,从开口处观察可以发现亮度不连续分布的光环.本文利用平面镜实验初步验证了产生该现象的基本原理.通过建立模型,运用MATLAB进行模拟,对该现象产生的基本原理进行解释.最后采用实验与模拟结合的方式对影响光环的系列因素进行探究.     

托卡马克中磁流体不稳定性与高能量离子相互作用

在托卡马克中,磁流体不稳定性与高能量离子相互作用是一个非常重要的问题,它对未来聚变堆稳态长脉冲运行至关重要。HL-2A是我国第一个具有先进偏滤器位形的非圆截面的托卡马克核聚变实验研究装置。撕裂模是托卡马克中的一种基本的电阻磁流体不稳定性,它可以改变磁场的拓扑结构,形成输运短路,甚至会触发大破裂。高能量离子在燃烧等离子体和各种外部辅助加热过程中是不可避免会产生的。目前,撕裂模与高能量离子相互作用依然存在一些关键性问题,例如撕裂模与高能量离子相互作用的共振关系、该物理过程导致高能量离子损失的物理机理等,并且还没有完整的关于撕裂模与高能量离子共振相互作用的数值模拟工作。因此,本综述论文主要从以下三个方面展开:1)回顾撕裂模与高能量离子相互作用的研究历史;2)基于HL-2A实验,从数值模拟的角度讨论撕裂模与高能量离子共振相互作用的物理机理以及其导致高能量离子损失的物理机制;3)展望未来聚变堆中撕裂模与高能量离子相互作用的情况。     

小型整体径向传输线的设计与实验

设计了一个小型整体径向传输线并对其传输特性进行了实验研究。该传输线由两块相距1 cm的铝合金平板组成，其特征阻抗采用双曲线型。1个输出端口位于传输线中央，20个输入端口均匀分布在传输线的外圆周上，最多可供20路脉冲同时注入。此传输线浸没于去离子水中，其单向传输时间为15 ns。负载由20个154 的电阻并联而成，以保证输出端的阻抗匹配。实验测得的输出电压波形与3维电磁场仿真结果非常接近。此外，还通过实验研究了不同驱动脉冲路数情况下小型整体径向传输线的输出电压，发现在驱动脉冲路数较少的情况下，输出电压的幅值几乎正比于驱动脉冲的路数。