强流脉冲离子束模型及辐照靶材能量沉积的模拟研究

强流脉冲离子束(IPIB)及其在靶材中沉积的能量是研究束流与靶材作用的基础.根据三束材料改性国家重点实验室从俄罗斯引进TEMPⅡ型加速器实测的磁绝缘二极管(MID)的加速电压波形及法拉第杯检测到的MID焦点处离子流密度波形,对其进行拟合得到高斯脉冲分布模型,以此为基础采用Monte Carlo方法模拟了离子在铝靶内沉积的能量,得到了一个脉冲内靶材内沉积的能量的时空演化规律.计算了单能离子束以20°～40°角入射铝靶情形.不同能量的单能H+束和C+束以一定角度入射时的最大射程比垂直入射时都要小,表面处单位长度沉积的能量随入射角的增加而增多.IPIB入射铝靶时变化规律同单能离子束.同时对H+和C+二维入射靶材情况也进行了模拟研究.     

Dynamics of Dust in a Plasma Sheath with Magnetic Field

Dynamics of dust in a plasma sheath with a magnetic field was investigated using a single particle model. The result shows that the radius, initial position, initial velocity of the dust particles and the magnetic field do effect their movement and equilibrium position in the plasma sheath. Generally, the dust particles with the same size, whatever original velocity and position they have, will locate at the same position in the end under the net actions of electrostatic, gravitational, neutral collisional, and Lorentz forces. But the dust particles will not locate in the plasma sheath if their radius is beyond a certain value.     

Numerical Research on Plasma Generation and Expansion into Vacuum

Energy deposition of intense pulsed ion beam （IPIB） on the Ti target based on the 2D model of IPIB density has been simulated by the Monte Carlo （MC） method. Taking the deposited energy as the thermal source, we have established the ablation model of the target and calculated the spatial and temporal evolution of the ablation shape of the Ti target irradiated by IPIB with different energy densities. We have also established the ejection model of the hydrodynamic equations related to the ablation shape of the target by using the ablation results as the initial conditions of plasma formed by IPIB irradiation. The spatially and temporally evoluted profiles of the plasma pressure and mass density are calculated.     

加速求积法及其应用

本文对估算环形电流的势、场以及自感、互感中所涉及的形如 B=integral from n=o to ∞ (d g(k)K_1(kr)sin(kz))和 B=-integral from n=0 to ∞ (d g(k)K_0(kr)cos(kz))的一类积分,采用加速求积法,获得了满意的结果。同时证明了,对常见的也是应用上很重要的一些类型的被积函数,如有理分式、指数函数、对数函数、三角函数、贝塞尔函数以及它们相互组合的函数,采用加速求积法是行之有效的。可见,加速求积法在应用上具有一定的广泛性。     

Configuration of 2D Finite Clusters in Plasma Sheath

Finite clusters with a small number of charged particles immersed in a plasma environment have been numerically simulated with a dynamic method. Finite Coulomb clusters are systems of a small number of charged particles, N = 1 to 100, confined by a potential produced by plasma 2D-sheath. Under the action of net force each particle is in an equilibrium position and together they form finite Coulomb clusters. The results of our study show the configuration of Coulomb clusters do not depend on their initial state. After theoretically studied and tested by using the Monte Carlo technique we also prove the system energy is the determinant parameter of the configuration. In addition, the effect of the external magnetic field on the cluster configuration is analyzed.     

Numerical Study on the Two-Dimensional Temperature Fields of Titanium/Aluminum Double-Layer Target Irradiated by High-Intensity Pulsed Ion Beam

Interaction between high-intensity pulsed ion beam (HIPIB) and a double-layer target with titanium film on top of aluminum substrate was simulated. The two-dimensional nonlinear thermal conduction equations, with the deposited energy in the target taken as source term, were derived and solved by finite differential method. As a result, the two-dimensional spatial and temporal evolution profiles of temperature were obtained for a titanium/aluminum double-layer target irradiated by a pulse of HIPIB. The effects of ion beam current density on the phase state of the target materials near the film and substrate interface were analyzed. Both titanium and aluminum were melted near the interface after a shot when the ion beam current density fell in the range of 100A/cm2 to 200A/cm2.     

用热电偶测定表面温度

用热电偶测定表面温度,目前已在建筑方面广泛采用。但是,如何消除产生的测量误差尚缺乏资料。 本文分析了用热电偶测定表面温度时测量误差产生的主要原因,并通过精确的实验和分析,提出了测定表面温度时获得较小误差的方法。     

轴向磁场中电弧螺旋不稳定性的简化数值分析

在静电近似下，通过数量级的分析，简化了能量方程。用数值方法研究了外加轴向磁场，电流分布、弧电流等对电弧曙旋不稳定性的影响。数值结果表明，在具有外加磁场情况下，当弧柱内均匀电流分布时，正向磁场能够使短波长的扰动稳定，反向磁场能够使长波长的扰动稳定。当弧柱内电流为抛物线形分布时，外加正向磁场对于短波情况下的稳定性影响很小，但对于长波情况，稳定性增强，外加反向磁场，同样能稳定中等和长波情况下的电弧。