共查询到18条相似文献,搜索用时 140 毫秒
1.
2.
深入研究潘宁放电的物理机制, 研制了全三维高品质算法粒子模拟软件(PIC), 设计并添加了相应物理情景的蒙特卡罗碰撞模块(MCC), 并对电子、氢分子离子(H2+)、氢正离子(H+)、氢三正离子(H3+)同时进行了跟踪, 成功研制了全三维电磁PIC/MCC数值算法. 结合国内研究较热的潘宁放电模型, 对该算法进行模拟验证. 模拟结果显示: 采用有效的滤波算法能抑制电磁数值噪声, 电子能量呈麦克斯韦分布, 由于电子的径向漂移和加速导致离子源顶端H2+产量较大.
关键词:
潘宁离子源
高品质算法
粒子模拟/蒙特卡罗 相似文献
3.
深入研究电子束对中性气体电离的物理机理,在粒子模拟(PIC)软件CHIPIC的基础上,设计了蒙特卡罗(MCC)电离碰撞模块,并对电子与离子同时进行了跟踪,成功研制了全三维电磁PIC/MCC代码.通过该软件对填充氦气相对论返波管的模拟,对全三维电磁PIC/MCC代码进行验证.模拟结果显示:填充气体可以中和空间电荷限制效应,有效提高电流大小;填充适量的气体可提高功率峰值,扩展脉冲宽度;过量的气体则会缩短脉冲宽度、降低峰值功率. 相似文献
4.
5.
6.
7.
对自主开发的全三维粒子模拟/蒙特卡罗(PIC/MCC)算法进行了阐述,包括算法流程设计、碰撞处理机制等。采用该算法对中国原子能科学研究院研制的15~20mA负氢离子源进行数值模拟研究,结果显示:该多峰会切离子源能得到空间分布均匀的离子束,采用优化后的虚拟过滤场,不仅能有效过滤高能电子,还将导致离子源下游区域低能电子增多,有效提高负氢离子体积产生效率。 相似文献
8.
采用粒子模拟与蒙特卡罗相结合(PIC/MCC)的方法,应用电磁模型,编写了准三维的电子回旋共振(ECR)放电电离过程的模拟程序,得到了ECR放电过程中电子与离子的相空间分布、电磁场分布.通过对这些分布随时间演化的分析,得出ECR加热发生在ω≈ωc0且垂直于轴向的区域;ECR区域,微波能量几乎全部耦合给电子,获得能量的电子通过与中性粒子的电离碰撞产生了大量的带电粒子;随着放电的进行,大量带电粒子通过频繁的碰撞,分布由各向异性逐渐趋于各向同性.
关键词:
电子回旋共振放电
粒子模拟
蒙特卡罗
电离 相似文献
9.
10.
在等离子体粒子模拟中,TA模型和NanBu模型被广泛用于处理库仑碰撞,这两种模型要求每个时间步长内全部粒子参与计算。为了降低参与碰撞的粒子数,提高库仑碰撞的计算效率,提出了一种基于截面的库仑碰撞模拟方法,并给出了库仑碰撞概率的计算公式。采用该方法对不同温度不同密度电子气的弛豫过程进行模拟,分别对比了电子速度分布函数、电子温度以及电子x、y方向上的温度与电子温度之比的模拟值与理论值,验证了该方法的准确性。在相同的小时间步长上,该方法相比TA模型计算效率提升可达40%以上。对于较大的时间步长,该方法仍能得到与理论解近似的模拟结果,相比Nanbu模型,在相同的精度下可取更大的时间步长,计算效率也有所提升。研究表明,该方法同样适用于电子-离子碰撞。因此在提高库仑碰撞计算效率上,该方法具有碰撞粒子数少以及适用于大时间步长的优势。 相似文献
11.
Chiaming Wang Tungyou Lin Russel Caflisch Bruce I. Cohen Andris M. Dimits 《Journal of computational physics》2008,227(9):4308-4329
The interactions of charged particles in a plasma are governed by long-range Coulomb collision. We compare two widely used Monte Carlo models for Coulomb collisions. One was developed by Takizuka and Abe in 1977, the other was developed by Nanbu in 1997. We perform deterministic and statistical error analysis with respect to particle number and time step. The two models produce similar stochastic errors, but Nanbu’s model gives smaller time step errors. Error comparisons between these two methods are presented. 相似文献
12.
In this theoretical work a 0-D model for a self-sustained X-ray preionized XeCl-laser discharge is presented. The model is self-consistent in the sense that it simultaneously solves, contrarily to the usual decoupling procedure, the Boltzmann equation for electrons, the kinetic equations for excited and ionic species, the equations for the electrical circuit and the laser photon density. It includes a rather complete kinetics of HCl(v) vibrational excitation, dissociation and dissociative attachment. The influence of electron collisions with excited species and of e-e Coulomb collisions on the plasma parameters and transport coefficients is discussed. Some evidence of the non-stationary equilibrium between the electron distribution and the reduced electric field E/N is given. Results of the model are compared with experimental ones corresponding to a XeCl-laser discharge driven by a L-C inversion circuit. The model predicts well the main trends for the variation of the laser energy in a large range of experimental conditions. The discrepancy between experiment and model for absolute values of the laser energy is discussed. 相似文献
13.
Andris M. Dimits Chiaming Wang Russel Caflisch Bruce I. Cohen Yanghong Huang 《Journal of computational physics》2009,228(13):4881-4892
We investigate the accuracy of and assumptions underlying the numerical binary Monte Carlo collision operator due to Nanbu [K. Nanbu, Phys. Rev. E 55 (1997) 4642]. The numerical experiments that resulted in the parameterization of the collision kernel used in Nanbu’s operator are argued to be an approximate realization of the Coulomb–Lorentz pitch-angle scattering process, for which an analytical solution for the collision kernel is available. It is demonstrated empirically that Nanbu’s collision operator quite accurately recovers the effects of Coulomb–Lorentz pitch-angle collisions, or processes that approximate these (such interspecies Coulomb collisions with very small mass ratio) even for very large values of the collisional time step. An investigation of the analytical solution shows that Nanbu’s parameterized kernel is highly accurate for small values of the normalized collision time step, but loses some of its accuracy for larger values of the time step. Careful numerical and analytical investigations are presented, which show that the time dependence of the relaxation of a temperature anisotropy by Coulomb–Lorentz collisions has a richer structure than previously thought, and is not accurately represented by an exponential decay with a single decay rate. Finally, a practical collision algorithm is proposed that for small-mass-ratio interspecies Coulomb collisions improves on the accuracy of Nanbu’s algorithm. 相似文献
14.
In this paper the processes of excitation and ionization inside the cathode of a hollow cathode are discharge will be studied. The electron energy distribution function is calculated from the kinetic equation. For this we take into account the following processes: elastic and inelastic collisions of electrons with atoms, Coulomb interaction between emitted fast electrons and electrons of the plasma. 相似文献
15.
The paper deals with the impact of intensive electron attachment on the kinetics of the electrons in the active zone of the stationary band-like beam discharge plasma in SF6 which is an alternative useful plasma medium for “dry etching”. The energy distribution of the electrons in this plasma was obtained by numerically solving the Boltzmann equation which includes apart from elastic collisions, different exciting collision processes, attachment in electron collisions, direct ionization, the ambipolar loss of electrons, Coulomb interaction between electrons and of electrons with ions and the power input to the electrons by the turbulent electric field. In particular, due to the needed fulfilment of the consistent electron particle balance, for an extended region of the turbulence energy density in this plasma a large impact on the electron kinetics of the intensive electron attachment, which is the prevailing electron loss process, was found enforcing independent of the turbulence energy density always a large power input to the electrons, smooth and only slowly decreasing energy distributions even in the energy region of direct ionization. 相似文献
16.
Experiments have been performed in which ion-induced Auger electron yields of Mg, Al and Si were measured as a function of ion energy. A computer simulation based on a binary collision cascade model yielded results that were in close agreement with the experimental findings. From this a model is proposed, where the creation of inner shell vacancies occurs during symmetrical collisions in the collision cascade generated by the ion. From the minimum energy required for Auger emission a distance of closest approach between the particles can be derived, using the Molière approximation of the screened Coulomb potential to describe the collisions. This distance can be correlated with the radii of the interacting orbitals derived from Hartree-Fock-Slater calculations. 相似文献
17.
18.
受激发射泵浦得到的LiCs高位振动态与CO_2碰撞,研究了LiCs不同能量对碰撞能量转移过程的影响.利用高分辨率瞬时激光感应荧光(LIF)测量得到CO_2(0000,J=2-74)原生转动态分布.转动布居数的半对数描绘给出了一个双指数结构,得到了一个T_a=660±73K[对LiCs(E=4300cm~(-1))]和550±61K[对LiCs(E=3700cm~(-1))]的低能分布,一个T_b=2380±261K[对LiCs(E=4300cm~(-1))]和1980±217K[对LiCs(E=3700cm~(-1))]的高能分布,低能分布属于弹性或弱非弹性碰撞,高能分布属于强非弹性碰撞.转动分布对LiCs能量是敏感的.但弹性与非弹性分支比基本是相同的.在一次碰撞的条件下,测量了各J态的出现和倒空速率系数,它们仅弱依赖于LiCs激发能.出现和倒空速率系数对不同LiCs能量基本一致,是振动-转动/平移弛豫轨道的重要证据. 相似文献