近物所在产生金属离子束方面的研究

Since 1998,many experiments for metallic ion production have been done on LECR2(Lanzhou ECR ion source NO.2),LECR3(Lanzhou ECR ion source NO.3)and SECRAL(Superconductiong ECB ion source Advanced design in Lanzhou)at Institute of Modern Physics.The very heavy metallic ion beams such as those of uranium were also produced by the plasma sputtering method,and supplied for HIRFL(Heavy Ion Research Facility in Lanzhou)accelerators successfully.During the test,11.SeμAU~(28 ),9eμAU~(24 ) were obtained.Some ion beams of the metal having lower melting temperature such as Ni and Mg ion beams were produced by oven method on LECR3 too.The consumption rate was controlled to be lower for ~(26)Mg ion beams production,and the minimum consumption was about 0.3mg per hour.In this paper,the main experimental results are given.Some discussions are made for some experimental phenomena and results,and some conclusions are drawn.     

电子辅助热丝化学气相沉积金刚石薄膜中氢原子谱线与最佳成膜条件

采用蒙特卡罗方法,对以CH4／H2混合气体为源气体的EACVD中的氢原子发射过程进行了模拟。研究了不同实验条件下产生的H、CH3的数目与氢原子谱线相对强度的关系,给出了一种利用氢原子谱线来获得最佳成膜实验条件的方法。本工作对于有效控制工艺条件,生长出高质量的金刚石薄膜具有重要意义。     

泵浦光调制对Ce:KNSBN光折变晶体全息存储质量的改善

实验研究了泵浦光斩波、斩波占空比、斩波频率对两波耦合过程及光扇噪声的影响,结果说明斩波调制抑制了光扇噪声,Ce:KNSBN晶体体全息存储再现图像质量得到明显改善.     

橡胶环直径方向受压大变形问题

本文基于变形梯度和分解定理(S-R定理)和拖带坐标描述法,应用有限元方法,计算了橡胶环直径方向受压接触大变形问题。并将结果与Durelli的实验进行了系统的比较,取得了令人满意的相符结果。表明了本程序在计算大变形问题时具有较高计算速度和精度之优点。     

ON LARGE DEFORMATION UNILATERAL CONTACT PROBLEM WITH FRICTION (I)—INCREMENTAL VARIATIONAL EQUATIONS

Based on the theory and technique of nonlinear geometric field theory of continuum, a more general incremental variational equation for elastic and plastic large deformation in co-moving coordinate is established in this paper. An expression for two and three-dimensional continua is derived, and the incremental variational equation for large deformation of changing boundary contact and the variational inequality in rate form are obtained, which provides the theoretical basis for the computation of elastic-plastic large deformation contact problem with friction.     

论拖带坐标系中应力的客观速率

应力客观速率是有限变形力学中一个十分重要的问题,本文利用非线性几何场论方法,推导出拖带坐标系中应力客观速率公式,并应用新公式计算了拉伸、拉伸与转动复合、简单剪切大变形问题.通过将计算结果与用Jaumann等其它应力速率计算的结果进行比较,说明了本文所得结果是合理的.     

氢原子谱线测定EACVD中电子平均温度

采用蒙特卡罗方法,对以CH₄/H₂混合气体为原料气体的EACVD中氢原子的发射过程进行了模拟。在模拟中考虑了电子与H₂的弹性碰撞及振动激发、分解、电子激发、相应于H_α, H_β, H_γ谱线的激发、电离及分解电离等非弹性碰撞过程;与CH₄的碰撞考虑了弹性动量传输及振动激发、分解、电子激发、电离及分解电离等非弹性碰撞过程。研究了不同CH₄浓度下基片表面上电子平均温度与氢原子谱线相对强度的关系,给出了一种对EACVD中电子平均温度进行实时监测的方法。对于有效控制工艺条件,生长出高质量的金刚石薄膜具有重要意义。     

电子助进化学气相沉积金刚石中衬底温度对发射光谱的影响

采用蒙特卡罗方法,对以CH4/H2为源料气体的电子助进化学气相沉积(EACVD)金刚石中的氢原子(H_α,H_β和H_γ)、碳原子C(2p3s→2p2: λ=165.7 nm)以及CH(A2Δ→X2Π: λ=420～440 nm)的发射过程进行了模拟,研究了衬底温度对各发射谱线以及金刚石膜合成的影响。结果得知,各谱线强度随衬底温度的变化幅度很小,且在衬底表面附近的谱线强度随衬底温度的变化幅度相对于远离衬底的反应区域较大,这表明衬底温度的变化基本上不改变远离衬底的反应区域中反应基团成分,而只对衬底表面附近的反应过程有影响。由此得知,衬底温度对薄膜质量的决定性主要是由于衬底温度改变了衬底表面化学反应动力学过程和表面附近的反应基团的缘故,而不是衬底温度对反应空间中气相成分的影响。     

Experimental results of helicon source

Helicon plasma sources are known as efficient generators of uniform and high density plasma. A helicon plasma source was developed for the investigation of plasma stripping and plasma lenses at the Institute of Modern Physics, CAS. In this paper, the characteristics of helicon plasma have been studied by using a Langmuir four-probe and a high plasma density up to 3.9× 10^13/cm^3 has been achieved with the Nagoya type III antenna. In the experiment, several important phenomena were found： （1） for a given magnetic induction intensity, the plasma density became greater with the increase of RF power; （2） helicon mode appeared at RF power between 300 W and 400 W; （3） the plasma density gradually tended to saturation as the RF power increased to the higher power; （4） a higher plasma density can be obtained by a good match between the RF power and the magnetic field distribution. The key issue is how to optimize the matching between the RF power and the magnetic field. Moreover, some tests on the extraction of ion beams were performed, and preliminary results are given. The problems which existed in the helicon ion source will be discussed and the increase in beam density will be expected by extraction system optimum.     

用于聚焦离子束系统的离子源

介绍了现阶段两种用于聚焦离子束系统的离子源——液态金属离子源和气体场发射离子源的基本原理, 并对比了它们的优缺点。由于目前这两种离子源都难以满足纳米加工领域不断提高的技术要求, 因此提出了一种用于聚焦离子束的新型离子源——电子束离子源, 并介绍了电子束离子源的基本原理, 给出了设计参数、 模拟结果（20 kV的Ar+离子束, 发射度约为5.8×10-5·mm·mrad, 束斑约为1 μm）和初步的实验结果。 There are two kinds of ion sources, Liquid Metal Ion Source and Gas Field Ion Source, used to provide ion beams for the Focus Ion Beam system. The working mechanism of the two kinds of sources is presented and their advantages and disadvantages are summarized. With the rapid development in the nano technology, the requirements are hardly met with these two kinds of ion sources. Therefore, a new kind of ion source, electron beam ion source, is developed for the Focus Ion Beam system. The basic principle of the electron beam ion source is introduced and the design parameters, the result of the simulation (20 kV Ar+, extracted emittance is 5.8×10-5π·mm·mrad, raduis of the ion beam about 1 μm.) and the primary experimental results are presented