Low energy range dielectronic recombination of Fluorine-like Fe~(17+) at the CSRm

The accuracy of dielectronic recombination(DR) data for astrophysics related ions plays a key role in astrophysical plasma modeling. The absolute DR rate coefficient of Fe~(17+) ions was measured at the main cooler storage ring at the Institute of Modern Physics, Lanzhou, China. The experimental electron-ion collision energy range covers the first Rydberg series up to n= 24 for the DR resonances associated with the ~2 P_(1/2)→~2 P_(3/2)△n =0 core excitations. A theoretical calculation was performed by using FAC code and compared with the measured DR rate coefficient. Overall reasonable agreement was found between the experimental results and calculations.Moreover, the plasma rate coefficient was deduced from the experimental DR rate coefficient and compared with the available results from the literature. At the low energy range, significant discrepancies were found, and the measured resonances challenge state-of-the-art theory at low collision energies.     

储存环HIAF-SRing等时性模式的非线性磁场影响研究

高精度环形谱仪SRing（Spectrometer Ring）是强流重离子加速器装置（HIAF）的重要组成部分,其等时性模式为远离β稳定线的短寿命原子核质量和寿命的精确测量提供国际领先的科研条件。为了扩大短寿命原子核质量测量精度和范围,SRing等时性模式设计了两种光学:γ_t=1.43和1.67。质量分辨是衡量等时性储存环的最重要参数。二极磁铁的高阶场以及磁铁的边缘场能强烈地引起束流光学高阶畸变,对质量分辨产生影响,因此需要高极磁铁对其进行校正。介绍了SRing等时性模式的线性计算,对非线性磁场的影响进行了详细研究。应用六极磁铁和八极磁铁对非线性场和发射度的影响进行了校正后,离子的循环时间标准偏差σ（T）/T达到3.5×10-7,质量分辨△m/m达到1×106。The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility (HIAF) project in China offers the capacity of measuring the mass and half-life of short-lived nuclides. The transition energy settings of the SRing are 1.43 and 1.67, which have been calculated in the same injection scheme. The resolution of mass or revolution time is the most important parameter of the isochronous mode design of a storage ring. The nonlinear magnetic field errors, including high-order magnet field of dipole, fringe field of magnets, have strongly effect to the resolution of revolution time. High-order corrections are required to improve the resolution of revolution time and mass. In this paper, the SRing linear isochronous optical were shown. The influence of nonlinear magnetic field errors on the revolution time resolving power were investigated. With 3 sextupole families and 1 octupole family corrections, the relative variation of revolution time reaches 4.6×10-7 with the momentum spread of ±0.2%. The relation of the relative standard revolution time deviation σ(T)/T and revolution turns was researched. With corrections of high-order isochronous condition and emittance influence by 3 sextupole families and 1 octupole family, one can reach a resolution of up to σ(T)/T=3.5×10-7, which corresponds to the mass resolution of △m/m=1×106.     

平面激光诱导荧光技术在交错电极介质阻挡放电等离子体研究中的初步应用

利用平面激光诱导荧光技术对交错电极介质阻挡放电过程中产生的痕量组分NO进行了检测. 通过数值模拟对实验结果进行了分析说明,并对介质阻挡放电等离子体流动控制原理进行了简要分析. 此外还通过平面激光诱导荧光技术对等离子体诱导流动进行了直观显示. 关键词： 平面激光诱导荧光 等离子体 介质阻挡放电     

具有初挠度的柔韧圆板的振动问题

本文推导出具有初挠度柔韧圆板的振动方程,在相平面上讨论了运动稳定性.用Galerkin法和Lindstedt-Poincaré摄动法求得具有初挠度圆板非线性振动的周期解,讨论了初挠度对柔韧圆板的动力特性的影响.     

网格湍流对剪切层中预混火焰结构的影响

本文研究网格湍流对射流剪切层以及建立在其中的预混火焰的影响。利用热线风速仪测量射流的速度场,发现网格湍流使剪切层内湍流强度明显降低,抑制了低频速度脉动,同时增加了湍动能在小尺度脉动上的分配,使湍流更趋于各向同性,这表明网格湍流抑制了剪切层内的大涡和拟序结构。用细丝热电偶测量了火焰温度,结果显示网格湍流使火焰前峰的低频大幅摆动减少,小尺度皱褶增加,火焰区平均温度更高,说明网格湍流有利于剪切层中预混火焰的强化和稳定。     

HIRFL-CSR主环加速腔系统设计

正在建设中的兰州重离子加速器冷却储存环 ( HIRFL- CSR)的主环加速腔系统用于将累积的重离子束流进行加速 .其频率范围为 0 .2 5 - 1 .7MHz,峰值电压为 8.0 k V.重点介绍了主环加速腔系统的设计及主要高频参数 ,包括高频腔体的设计及低电平控制部分的设计. An ion cooler storage ring HIRFL CSR is constructing at Institute of Modern Physics(IMP). It consists of two rings--main ring (CSRm) and experimental ring (CSRe). For the CSRm, two RF systems will be employed. One is for RF stacking, and another is for beam accelerating. The designed parameters of CSRm accelerating system and the control block diagram of RF system are described. The RF accelerating system has a specification of lower and wider frequency range from 0.25 to 1.7 MHz...     

螺线管磁场缺陷对电子束横向温度的影响

分析了直螺线管磁场缺陷的来源,考虑了电子束的空间电荷作用,采用数值方法模拟计算了磁场缺陷对电子束横向温度的影响 ,获得了电子冷却装置中直螺线管磁场的均匀性要求.结果表明,当相对磁场缺陷小于1× 1 0-3时 ,影响可以被忽略.In order to obtain the tolerance requirement for the magnetic field homogeneity of the solenoids in electron cooling device, the source of the magnetic imperfection and its influence on the transverse temperature of electron beam were investigated by means of numerical simulation, and taking the space charge effect of electron beam into account. The calculated result shows that the influence of the imperfection of magnetic field will be negligible when the relative magnetic field...     

GDM模型及2000年中国人口生存函数预测

Maisano在De Moivre线性模型的基础上,提出了具有良好拟合效果的人口生存函数GDM模型。本文将利用GDM方法对我国历年人口数据进行模型拟合,并对2000年中国人口的生存函数进行预测。     

缺失数据的加权调整(系列之Ⅳ)

加权调整法是通过给回答数据赋以不同的权数 ,然后再进行数据处理 ,以此减小无回答偏差。本文介绍了三种调整方法 ,分别是 :波利茨—西蒙斯调整 ;加权组调整及事后分层调整     

缺失数据的偏差校正(系列三)

调查中的缺失数据会造成估计量的偏倚。有一些简单易行的对数据进行调整的方法 ,如果使用得当 ,可以减小由于缺失数据造成的估计量偏倚。本文介绍了三种常用的方法 :即 ,再抽样调整 ;多次调查数据调整和相关推估法