激光等离子体中横场坍塌形成的密度空穴

强激光与等离子体相互作用时在临界面附近发生强烈的波-波、波-粒相互作用,原来均匀分布的横等离子体波在调制不稳定作用下,发生坍塌破碎,局域化的高强度横等离激元通过有质动力排斥粒子形成密度空穴,同时诱发出高强度的低频磁场.采用从伏拉索夫方程和麦克斯韦方程组导出的非线性控制方程,数值模拟了非静态极限情况下无碰撞等离子体中密度空穴和低频磁场的演化过程.     

三能级原子与双模场多光子相互作用的量子动力学性质

研究三能级原子与双模场多光子相互作用过程中,原子能级占据几率的量子动力学行为。显然,本文的结果与单光子跃迁过程中的结果完全不同。     

Kinetic theory of Jeans' gravitational instability in millicharged dark matter system

The possibility of baryons cooled by a millicharged dark matter (mDM) via mDM-baryons scattering has recently been proposed to explain the observation discrepancy from the experiment to detect the global epoch of reionization signature (EDGES). In this sense, we analyze the Jeans instability of self-gravitational systems in the background of mDM under kinetic regime that the collisionless Boltzmann equation and Poisson equation have been combined to obtain the modified dispersion relation. It is shown that the effect of mDM is significant on the dynamics of gravitational collapse, i.e., the presence of mDM makes the self-gravitational systems more difficult to collapse relatively.     

Effects of Higher-Order Relativistic Nonlinearity and Wakefield During a Moderately Intense Laser Pulse Propagation in a Plasma Channel

Using a variational approach,the propagation of a moderately intense laser pulse in a parabolic preformed plasma channel is investigated.The effects of higher-order relativistic nonlinearity (HRN) and wakefield are included.The effect of HRN serves as an additional defocusing mechanism and has the same order of magnitude in the spot size as that of the transverse wakefield (TWF).The effect of longitudinal wakefield is much larger than those of HRN and TWF for an intense laser pulse with the pulse length equaling the plasma wavelength.The catastrophic focusing of the laser spot size would be prevented in the present of HRN and then it varies with periodic focusing oscillations.     

两个级联型三能级原子受激辐射的非线性性质

本文研究了两个级联型三能级原子同单模腔场的非线性相互作用.研究表明: 在激发场场强达到一定阈值以后, 两个原子的合作辐射效应变成同步辐射, 即多原子系统在一定阈值条件下可以有组织成相当于一个大原子的系统, 而产生同步有序辐射. 同时, 由于这种同步辐射效应, 两原子系统的受激辐射的二阶相干度相对于单原子系统的要大, 即聚束效应强而反聚束效应弱. 另外, 两原子系统由于多光子过程的加强而有更深的压缩效应, 此时要求的激发场场强也比单原子系统的要强. 关键词：     

基于纠缠的数据链路层量子通信协议

利用量子力学中的纠缠关联性，提出了数据链路层的量子通信协议. 该协议把线路分为忙闲时段，量子纠缠态的分发预先在闲时段完成，数据经由经典链路发送，确认帧经由量子纠缠信道发送. 量子信息的传输可以是瞬时的，因此两个发送成功的数据帧之间的最小时间间隔可以大为减小. 研究表明该协议能有效地提高数据链路的最大吞吐量，改善数据链路层停止等待协议的性能. 关键词： 量子通信 纠缠 停止等待协议 数据链路     

Electron Acceleration and Bunch Generation by Intense Femtosecond Laser Pulse in Preplasma of a Target

We present analytical studies of electron acceleration in the low-density preplasma of a thin solid target by an intense femtosecond laser pulse. Electrons in the preplasma are trapped and accelerated by the ponderomotive force as well as the wake field. Two-dimensional particle-in-cell simulations show that when the laser pulse is stopped by the target, electrons trapped in the laser pules can be extracted and move forward inertially. The energetic electron bunch in the bubble is unaffected by the reflected pulse and passes through the target with small energy spread and emittance. There is an optimal preplasma density for the generation of the monoenergetic electron bunch if a laser pulse is given. The maximum electron energy is inverse proportion to the preplasma density.     

激光在等离子体中的坍塌行径

 从椭圆偏振激光场波包所满足的非线性控制方程出发,利用场论方法,构造该非线性方程的拉格朗日密度函数,得到激光场波包的能量集中具有准粒子特性,并给出守恒的粒子数、动量和能量。讨论了调制不稳定发展后期的波包坍塌动力学问题,利用归一化的粒子数密度分布作为权重,分析了激光场的波包。结果表明,激光场波包的尺度在有限的时间进程中,将塌缩到一个很小的值,证明了激光场具有塌缩行径。     

流体模自引力系统的调制不稳定性

利用流体模自引力系统的结构方程,分析了流体模自引力系统的有限振幅的调制不稳定性,解析上获得了在两种特殊条件下纵扰动的时间增长率与扰动态波数之间的函数关系.最后用数值方法得到了一般情况下纵扰动的时间增长率关于扰动态波数的数值曲线,正好将两种特殊条件下的解析结果衔接起来,使其成为一条连续的曲线.从而,表明了解析结果的可靠性.     

非轴对称的吸积盘的不稳定性分析Ⅱ.气压为主要压力

针对非轴对称的吸积盘中压力主要为气压的区域,采用一种新的黏滞机制(反常磁黏滞),利用数值方法进行了吸积盘的不稳定性分析。结果表明,当吸积盘无黏滞时,吸积盘的稳定性不受不透明度的影响;随着方位角扰动波数n的增大,热模、黏滞模是越来越不稳定,In-模和Out-模则是越来越稳定