共查询到17条相似文献,搜索用时 140 毫秒
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采用蒙特卡罗模型对氮空心阴极放电等离子体鞘层离子(N2 、N )的输运过程进行了模拟研究,计算了阴极鞘层中氮离子(N2 、N )的能量及角分布的空间变化和粒子密度及平均能量随放电参数的变化规律。研究结果表明:空心阴极放电产生的氮离子,在鞘层输运过程中,N2 是密度几乎不变的低能粒子;N 是密度逐渐减少的高能粒子。随着电压增加,N 密度减小,平均能量增加;N2 密度和平均能量变化不明显。能量及入射角的相对分布规律与平板电极氮直流辉光放电基本类似,但圆筒空心阴极放电更有利于氮离子的产生。 相似文献
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ECR微波等离子体离子输运的数值模拟 总被引:2,自引:0,他引:2
建立了ECR微波等离子体源离子输运的平板和圆柱模型,对离子历经的空间区域的输运过程进行了数值研究。采用Monte Carlo(M-C)方法模拟了存在外磁场情况下,离子离开开放电室后历经中性区、鞘层区、最后被加负偏压的工作表面吸收的全过程,考虑了离子与中性粒子的电荷交换碰撞玫弱性散性,统一处理了中性区和鞘层区电势的衔接,采用曲线拟合,电势自洽迭代方法把中性区和鞘层区衔接起来,得到了光滑自治的电势分布曲线和鞘层区不同位置处的速度分布、能量分布及角分布。 相似文献
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基于OOPIC软件,对平面直流磁控溅射放电等离子体进行了二维自洽粒子模拟,重点研究了磁场、阴极电势和气压等工作参数对磁控放电特性的影响。模拟发现,在一定的工作参数范围内,随着磁场的增强,鞘层厚度变窄,鞘层电势降减小,阴极离子密度增大,但是分布变窄;随着阴极电势的增加,鞘层厚度稍微变窄,鞘层电势降增大,阴极离子密度增大,分布变宽;随着气压的升高,鞘层厚度基本不变,鞘层电势降会增大,阴极离子密度先增大后减小,分布略微变宽。 相似文献
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衬底偏压对ECR等离子体鞘层和离子行为的影响 总被引:1,自引:0,他引:1
介绍了电子回旋共振微波放电等离子体中离子向衬底输运的蒙特卡罗模型,该模型考虑了精确依赖于离子能量的电荷交换和动量转移截面以及中性区与鞘层的衔接。 相似文献
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建立了电子回旋共振(ECR)微波放电等离子体中离子输运过程的蒙特卡罗模型,考虑了离子与中性原子的电荷交换碰撞和弹性碰撞,以及精确依赖于离子能量的电荷交换和动量转移截面,模拟了源于氩气ECR微波放电的氩离子向衬底输运的过程,得到与实验报道相符的模拟结果。 相似文献
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V. V. Khvostov I. K. Khrustachev K. F. Minnebaev E. Yu. Zykova I. P. Ivanenko V. E. Yurasova 《Journal of Experimental and Theoretical Physics》2014,118(3):365-374
Secondary ion emission from silicon and graphite single crystals bombarded by argon ions with energies E 0 varied from 1 to 10 keV at various angles of incidence α has been studied. The evolution of the energy spectra of C+ and Si+ secondary ions has been traced in which the positions of maxima (E max) shift toward higher secondary-ion energies E 1 with increasing polar emission angle θ (measured from the normal to the sample surface). The opposite trend has been observed for ions emitted from single crystals heated to several hundred degrees Centigrade; the E max values initially remain unchanged and then shift toward lower energies E 1 with increasing angle θ. It is established that the magnitude and position of a peak in the energy spectrum of secondary C+ ions is virtually independent of E 0, angle α, and the surface relief of the sample (in the E 0 and α intervals studied). Unusual oscillating energy distributions are discussed, which have been observed for secondary ions emitted from silicon (111) and layered graphite (0001) faces. Numerical simulations of secondary ion sputtering and charge exchange have been performed. A comparison of the measured and calculated data for graphite crystals has shown that C+ ions are formed as a result of charge exchange between secondary ions and bombarding Ar+ ions, which takes place both outside and inside the target. This substantially differs from the ion sputtering process in metals and must be taken into account when analyzing secondary ion emission mechanisms and in practical applications of secondary-ion mass spectrometry. 相似文献
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S. Yu. Gus’kov V. B. Rozanov A. N. Cherkasov 《Journal of Experimental and Theoretical Physics》2003,97(5):932-947
We investigate the formation of the charge and energy distributions of ions that slow down and randomly change their charges in collisions with particles of the medium. We study the influence that the spread of ions in charge has on the shape of the Bragg curve. The suggested diffusion approximation for the kinetic equation of heavy ions allows the parameters of the ion charge and energy distributions to be easily determined in the entire ion path. The parameters of the ion charge distribution are shown to be related to the ionization-recombination cross sections. The ion distributions calculated in the suggested analytical model are compared with the results of numerical calculations. We have obtained good agreement between the analytical, numerical, and experimental results. 相似文献
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The present work deals with the spectroscopic investigation of Penning ionization and nonresonant charge exchange due to thermal-energy collisions of metastable atoms or ions of the inert gases He, Ne with atoms of alkali metals K, Rb, Cs in a low temperature plasma of the corresponding binary mixtures. The rate constants of these reactions and partial rate constants of exciting several alkali metal ion levels were determined by the kinetics of the decay of ionized and excited particles in the afterglow of a pulsed discharge. Measured Penning and charge exchange constants are in order of 1010-9 cm3 sec?1. Partial Penning constants in the He? Cs system exhibit a small dependence of the energy defect of reaction, whereby an important part of collisions results in excited Cs+-states. On the contrary, energy transfer by charge exchange in He? Rb, Cs systems distinguishes by a significant energy defect dependence. Charge exchange from He+ to Rb0 leads above all to He(23S1)-atoms and normal Rb+-ions. It follows from the metal ion spectrums, that Penning ionization and charge exchange of the investigated systems under utilized conditions represent as processes of selective excitation of alkali metal ions in afterglow and stationary discharge. 相似文献
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Energy and charge distributions of ions are calculated for a cluster beam irradiated by a high-power ultrashort laser pulse. It is shown that the self-consistent field of a cluster ionized by the laser beam strongly affects the characteristics of the ion distributions obtained after the cluster explodes. The mean concentration of atoms bound into clusters in a beam, the cluster size distribution, and the focal-spot diameter are found to have a weak effect on both energy and charge distributions of the ions, whereas the energy spectrum of the produced ions is determined by the mean cluster size. 相似文献
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《Surface science》1986,177(3):593-614
Ion energy distributions in low temperature field evaporation obtained by pulsed-laser time-of-flight atom-probe, in general, show a FWHM of the spatial zone of ion formation to be 0.3–0.5 Å; post field ionization is not responsible for the ion formation. However, when ions of two or more charge states coexist a low energy tail can be found for the higher charge state ions, similar to those found for gas ions in field ionization. This tail can extend as far as 10 Å above the surface. Ions in the tail can only be produced by post field ionization. Double peak structures are found in the energy distributions of some ion species such as Mo2+; the origin of which is not yet understood. At a constant rate of field evaporation, as the field is gradually reduced by continued field evaporation and the laser power density appropriately increased, the charge states shift to the lower ones. For Mo, however, Mo2+2 ions are formed before Mo+ ions can be detected. The narrowness of the energy distributions shows that they are stable. This finding has an important implication to the study of the stability or Coulomb explosion of multiple charged cluster ions, and also the theory of field evaporation. Under intense laser irradiation, higher charge state ions can reappear and a large fraction of ions may have an excess energy of a few hundred eV. These may be produced by multiphoton ionization and also by interaction with the over-heated electrons in laser-solid interactions. 相似文献