磁共振法研究(Fe1-xCox)84Zr3.5Nb 3.5B8Cu1纳米晶薄带的磁各向异性

铁磁共振（FMR）实验研究(Fe_1-xCo_x)₈₄Zr_{3.5 Nb3.5B8Cu1（x=0.0,0.2,0.4,0.6, 0.8）合金薄 带的各向异性，易轴在薄带的横向方向,同等宽度样品 的各向异性常数K′随Co掺杂量的增加而减小, K′值在4.67×10^-5　J/m（x=0. 0）到 2.54×10^-5　J 关键词： 铁磁共振 各向异性常数 低场非共振信号 磁化过程}     

体积算符对任意价顶角的本征作用与本征值谱

利用体积算符所含抓三元组对自旋网任意价顶角中圈线作用的反称化和双元恒等式，证明了这种作用均为本征作用，本征值为-2.用代数方法给出了对任意价顶角求体积算符本征值的系统程式，得到了普遍情况下的3，4，5和6顶角体积本征值的具体代数表式. 关键词： 体积算符 任意价顶角 本征作用证明 本征值谱     

缓变截面波导开放谐振腔的微波网络分析

本文利用微波网络理论分析了缓变截面波导开放谐振腔,给出了任意纵剖面形状开放腔的传输Q值的一般公式。估计了波导壁欧姆损耗对Q值的影响。简单讨论了谐振频率修正问题。并具体推导了双圆锥腔和圆柱形开放腔的传输Q值的计算公式。 关键词：     

晶体中稀土离子能级重心的位移

本文从理论上讨论了晶场作用对稀土离子能级重心位移的影响,具体计算了J混效应对15个含Nd³⁺离子的晶体中的⁴I_J能级重心的位移。结果指出J混效应加宽了光谱项^2S+1L由于自旋轨道耦合导致的能级劈裂宽度,并且与晶体基质的组成、结构有关。 关键词：     

环形轴对称锐边界等离子体的扭曲模不稳定性

本文对任意环径比、任意β值、任意截面形状的轴对称锐边界等离子体,给出了正确的边界条件,导出了无导体壳和存在导体壳两种情况下扭曲模稳定性的能量矩阵,对环向波数n为1,2,3的能量矩阵,给出了可快速、精确积分的具体形式,对不同环径比和不同拉长度b/α的椭圆形、跑道形(包括圆形)截面的等离子体进行了数值计算。计算结果表明,跑道形截面等离子体的临界β值比相应的椭圆形截面的β值高,随着b/α的增大,跑道形截面的临界β值也增加。导体壳有一定的稳定作用。从系统稳定性边缘态的本征矢量来看,存在导体壳时极向扰动的最大分量是模数1的扰动。与J.P.Freidberg和W.Grossmann的工作比较,在环径比为2时,圆截面等离子体的临界β值相差23％,临界q值相差15％。     

在辐射阻尼存在下有效横向弛豫时间T*2的快速测定

利用CPMG自旋回波技术,通过一连串180°脉冲抑制辐射阻尼效应,让磁化矢量经过横向弛豫T₂过程大幅度衰减后再检测回波信号的线宽,该方法可直接获得有效横向弛豫时间T*₂,并可在CPMG测试T₂值的同时进行. 另外,当饱和恢复法用于估计T*₂值时,信号检测必须使用小角度脉冲.所有结果已进行了实验验证.     

可调谐位相型光瞳滤波器的横向光学超分辨和轴向扩展焦深

为克服传统光瞳滤波器的缺点,实现系统光学超分辨性能的可调谐性,设计了一种新型可调谐的位相型光瞳滤波器.该光瞳滤波器包括两个λ/4波片和置于其间的λ/2波片,其中λ/2波片分为两个可作相对旋转的区域.研究结果表明,通过旋转λ/2波片的任意一区域不仅可以实现系统横向光学超分辨能力的可调性,而且可以在横向分辨能力提高的同时实现光学系统轴向焦深的扩展以及轴向焦移. 关键词： 光学超分辨 位相型光瞳滤波器 可调谐     

自旋结网圈表象中体积与面积本征值

利用抓算符作用的反称化和双元恒等式，通过计算，证明了3价和任意价自旋结网圈分别为体积和面积算符的本征态，并得到了体积本征值为2^-32l³₀∑ip_σp_τp_ρ和面积本征值为2^-1l²₀∑jp_l(j)的结果. 关键词： 体积算符 面积算符 本征值 自旋结网圈     

铒离子注入6H-SiC的横向离散研究

利用离子注入掺杂技术设计、制作半导体集成器件时,了解离子注入半导体材料的射程分布、射程离散和横向离散规律等是很重要的.用400 keV能量的铒(Er)离子分别与样品表面法线方向成0°,45°和 60°倾角注入碳化硅(6H-SiC)晶体中,利用卢瑟福背散射技术研究了剂量为5×10¹⁵ cm^-2 的400 keV Er离子注入6H-SiC晶体的横向离散.测出的实验值与TRIM98和SRIM 2006得到的理论模拟值进行了比较,发现实验值跟TRIM98和SRIM 关键词： 离子注入 6H-SiC 卢瑟福背散射技术 横向离散     

镜泊湖水体水溶性有机物荧光特性研究

通过黑龙江省区域镜泊湖水体6个点位样品采集(样品号J1-J6),利用荧光检测技术,结合三维荧光光谱区域积分(FIR),研究了水溶性有机物(DOM)的荧光特性。传统荧光光谱显示J4和J5 DOM分子缩合度较高;三维荧光光谱显示J6点位DOM中类蛋白特征峰最为显著;对所有点位DOM的三维荧光光谱5个区域积分(A_Ⅰ,A_Ⅱ,A_Ⅳ：类蛋白区域;A_Ⅲ：类富里酸区域：A_Ⅴ：类胡敏酸区域)显示：所有点位DOM区域积分中A_Ⅴ区域占有比例最大,并且以J4和J5点位最高,J6点位最低。通过对腐殖酸区域(A_Ⅲ和A_Ⅴ积分比例之和)与类蛋白区域(A_Ⅰ,A_Ⅱ,A_Ⅳ积分比例之和)积分比值表明,J4(4.94)和J5(5.18)点位比值相近;J1(3.52)和J2(3.66)点位比值接近;最小值为J6点位(2.11)。综合以上分析证实,镜泊湖水体各点位DOM腐殖化程度为：J4,J5>J1,J2>J3>J6点位。     

Convergence of general beams into Gaussian intensity profiles after propagation in turbulent atmosphere

It is shown that a general shaped laser beam will eventually approach a Gaussian average intensity profile after propagation in turbulent atmosphere. In our formulation, source field at the exit plane of the laser is taken as the product of arbitrary functions of source transverse coordinates with Gaussian exponential modulations. Following the expansion of the arbitrary functions in terms of Hermite polynomials, the average receiver intensity expression is derived using the extended Huygens-Fresnel principle and the conditions for the intensity profile to assume a Gaussian shape are stated. The results are illustrated by simulating various source field distributions.     

Output power optimisation of slab-waveguide laser with Gaussian output mirror

We present an approximate analysis of the nonlinear operation of the hollow slab-waveguide laser with Gaussian reflectivity profile output mirror, including gain saturation and longitudinal as well as transverse field distribution of the laser mode. The model presented is general and can be applied to the study of arbitrary configuration of the slab-waveguide laser. In particular, the laser characteristics obtained reveal the influence of the position of the output mirror and the Gaussian mirror parameter on the power efficiency of the laser system. Received: 6 January 2000 / Published online: 8 November 2000     

An analysis of the second order spatial coherence of stationary laser oscillators with a Fabry-Perot resonator

We investigate in this paper the results yielded by a rigorous application of second order spatial coherence theory to a Gaussian TEM-multimode laser beam. Formulae for a qualitative discussion and a quantitative evaluation of the second order spatial coherence properties of a laser oscillator with an arbitrary number of longitudinal and/or transverse Gaussian TEM-modes of oscillation are derived and considered for some practically important cases.     

激光等离子体在螺线管发散磁场中的特性研究

激光烧蚀等离子体(LAP)可用作粒子加速器和离子注入器中使用的离子源。相较于其它离子源,激光离子源在流强上具有优势,但由于产生的离子束脉冲时间短,限制了其在加速器中的广泛应用。实验中通过对激光等离子体扩散区域引入螺线管磁场进行约束,实现了对激光等离子体脉冲时间结构的调制。为了研究螺线管磁场对LAP的影响,实验使用了不同的激光能量(1~8 J)来生产具有不同初始条件的激光等离子体,并应用了不同的磁场强度来约束激光等离子体。在螺线管边缘场,通过可移动的法拉第筒(FC)对激光等离子体的横向分布进行测量。对于不同初始状态的等离子体,随着磁场的增加,其离子脉冲的主要参数(脉冲总电荷量、峰值流强、脉宽)均呈现先上升后逐渐饱和的变化趋势。另外,在没有磁场的条件下,在所测量位置处,等离子体的横向呈均匀分布;而在磁场约束的条件下,等离子体明显向轴线聚集。以上实验结果对进一步了解磁约束激光等离子体的特性具有重要意义。     

Parallel propagating modes and anomalous spatial damping in the ultra-relativistic electron plasma with arbitrary degeneracy

The dispersion relations of parallel propagating modes(Langmuir mode, right and left handed circular polarized waves) in the weak magnetic field limit |ω-k·v| ? are considered for ultra-relativistic arbitrary degenerate electron plasma. The results are presented in terms of moments of Fermi-Dirac distribution. The increase in the electron equilibrium number density from negative large(weakly degenerate) to positive large(highly degenerate) values of μ/T_e is observed(where μ is the electron chemical potential and T_e is the electron thermal energy). As a result, shifting of the cutoff points in all the real dispersion branches towards the higher values and increasing in the band gap between unmagnetized longitudinal and transverse modes in k-space are examined. Also, the suppression of the weak magnetic field effects in weakly magnetized right handed and left handed circular polarized waves and a decrease in the longitudinal and transverse screening effects are observed in the graphical patterns due to an increase in the equilibrium number density.     

The influence of collective effects on quantum fluctuations of laser radiation

Quantum fluctuations in a laser with two different relaxation times are considered, i.e., transverse (polarization relaxation) and longitudinal (population relaxation) in the case in which the cavity transmission band half-width is much smaller than the transverse width and much larger than the longitudinal one. The lasing frequency detuning from the transition frequency of a two-level system is assumed to be arbitrary in this case, and it is necessary to take into account the contribution of two-particle correlators into the dispersion and laser linewidth. The results are considered as applied to a semiconductor laser.     

Effect of electron reflection from the surface on the electromagnetic properties of cylindrical particles

The cross section of the absorption of a magnetic field by a cylindrical metal particle is calculated. The general case when the ratio of the electron mean free path to the particle transverse size may take arbitrary values is considered. The boundary conditions imply the mixed mirror-diffuse reflection of electrons from the inner surface of the particle. The limiting cases are considered and results obtained are discussed.     

Laser guiding of cold molecules in a hollow optical fiber and continuous-wave cold molecular beam generation

A novel scheme for guiding arbitrary buffer-gas cooled neutral molecules in a hollow optical fiber (HOF) using a red-detuned HE₁₁ mode is proposed and analysed theoretically. We give the electromagnetic field distribution of the HE₁₁ mode in the HOF and calculate the optical potential of an I₂ molecule, and study the molecule guiding mechanism using a classical Monte Carlo simulation. Using a 6 kW input laser, an S-shape HOF with a 2 cm curvature radius for both bends, and an input molecular beam with a transverse temperature of 0.5 K and longitudinal temperature of 5 K, we obtain a guiding efficiency of ～0.126% for the scheme, and the transverse and longitudinal temperatures of the guided molecular beam are 1.9 mK and 0.5 K, respectively.     

Cyclotron mechanism of electron acceleration in subpicosecond laser plasma

The effect of ultrastrong magnetic fields generated in a relativistic-intensity subpicosecond laser plasma on the acceleration of fast electrons was studied. It is shown that resonance electrons can continuously accumulate energy from the circularly polarized laser field in the presence of a longitudinal magnetic field. For the linear polarization and a transverse magnetic field, energy accumulation has a pulse-periodic character, and the electron trajectories correspond to electron rotation in the Larmor orbit in a quasi-stationary magnetic field, while the energy strongly oscillates. In both cases, electron energy may attain values higher than 100 MeV for intensities of 10²⁰ W/cm².