强流离子束离子径向密度分布的模拟研究

对初始分布为K-V分布的离子束进行模拟研究.除观察到存在束晕现象外，还发现离子束在通 道内运行过程中，离子沿径向密度分布发生了变化. 通过延迟反馈控制，不仅可以消除束晕 ，而且只要控制参数适当，也可以使束中心部分呈均匀分布状态. 关键词： 强流离子束 束晕 填充因子 离子密度分布     

稀土粉末Eu∶Y_2O_3的自由感应衰减量子拍

稀土固体是重要的激光和光电子材料。目前 ,由于以宽带信号和太赫兹比特数据传输率为特征的信息技术的发展 ,稀土固体材料的相干瞬态动力学过程成为宽带与高速信息光子学的基本物理问题之一。研究了室温下稀土粉末样品Eu3+ ∶Y2 O3自由感应衰减的相干瞬态光谱 ,这有助于理解有效的光吸收动力学、激发态弛豫、相干能量传递和超短光脉冲在稀土固体中的传播。用一对紫外飞秒相干光脉冲作用于稀土粉末样品Eu3+ ∶Y2 O3,然后监测物质激发态的布居数随两个激发脉冲之间的延时的变化 ,测量到其自由感应衰减量子拍 (FID) ,从拍频周期分析确定了其能级精细结构 ,能级的退相时间长达皮秒量级。理论分析和实验结果符合得很好。对稀土离子的量子干涉的研究 ,表明其在受激受控光放大方面具有潜在的应用前景     

超短脉冲超强激光与固体靶相互作用中高能离子的产生

 用2D3V PIC粒子模拟方法得到了超短脉冲超强激光与固体靶相互作用中高能离子产生的图像，并对其机理进行了研究。在靶前后表面都观察到了高能离子的产生，并诊断了离子能谱。模拟结果表明，在靶前表面所产生的高能离子，角分布较大，在向靶内输运过程中会损失能量；在靶后表面产生的高能离子，定向性很好，能获得很高的能量。模拟得到的离子能量和实验观测结果在量级上相符。     

氩离子激光器输出光功率稳定度与光反馈应用

通过实验观测氩离子激光器工作电流与输出光功率及其稳定性之间的关系，采用光反馈解决了反馈工作点的设置和跟踪调解，使输出光功率稳定性得到明显提高。     

含三正辛胺微胶囊对六价铬的富集

本文将对六价铬有效的萃取剂ＴＯＡ（三正辛胺）微胶囊化，制成填充柱型的酸性体系六价铬的富集分离装置。实验结果表明，微胶囊填充柱中每毫升ＴＯＡ对六价铬的最大萃取容量为１５８．０ｇ／ｍＬ，为纯ＴＯＡ液相萃取的４．９倍。微胶囊经碱／水洗涤后，可再生使用。     

量子计算与超冷离子

通过介绍量子计算的基本概念和特点，并对比目前人们使用的计算机的计算方式，对于如何利用囚禁在离子阱中的超冷离子进行量子计算作了简要的叙述．     

HoYb:YVO4的上转换发光研究

研究了960nm激光激发下HoYb双掺钒酸钇晶体HoYb:YVO4的直接上转换增敏发光,发现了Ho3+离子的上转换发光现象,HoYb:YVO4晶体的上转换发光是5F5→5I8最强,而5S2→5I8相对小了一个数量级,这是由于YVO4晶体既有很强的振子强度又有很大的多声子无辐射弛豫造成的. 关键词： 上转换发光 直接增敏(敏化) 钒酸钇YVO4晶体 Ho3+离子     

Measurement of storage time, estimation of ion number and study of absorption line profile in a Paul trap

Europium (Eu⁺) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu⁺ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions. The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both experimentally and theoretically.     

The Transport Properties of the Cell Membrane Ion Channels in Electric Fields: Bethe Lattice Treatment

The interactive two-state model of cell membrane ion channels in an electric field is formulated on the Bethe lattice by means of the exact recursion relations. The probability of channel opening or maximum fractions of open potassium and sodium channels are obtained by solving a non-linear algebraic equation. Using known parameters for the conventional mean-field theory the model gives a good agreement with the experiment both at low and high trans-membrane potential values. For intermediate voltages, the numerical results imply that collective effects are introduced by trans-membrane voltage.     

TRIUMF resonant ionization laser ion source

The range of isotopes available at the TRIUMF Isotope Separator Accelerator (ISAC) facility has been greatly enhanced by adding a Resonance Ionization Laser Ion Source (RILIS). A large wavelength range is accessible with the fundamental, second and third harmonic generation of titanium-sapphire laser light. In addition a dedicated laser is available for non-resonant laser ionization. The first on-line beam ⁶²Ga was delivered in Dec. 2004. In general RILIS improves the intensity, purity and emittance of ion beams. ⁶²Ga and ²⁶Al and Be beams have been delivered so far on-line. This work was financed by TRIUMF which is federally funded via a contribution agreement through the National Research Council of Canada.