Penning阱中离子谱的优化

根据Penning阱存储离子的探测原理,系统分析了阱内离子信号及信号本身的噪声、实验仪器及探测电路的噪声干扰,采用适当的品质因数和电子束流,得到较高信噪比和分辨率的离子谱。为深入开展Hn^＋（n≥3）对离子的形成机制、离子与中性气体原子或分子碰撞过程等问题的研究创造了更好的条件。     

An ion beam cooler for collinear laser spectroscopy

An ion beam cooler has been constructed and tested at the IGISOL mass separator facility at the University of Jyväskylä. The cooler is designed to improve the ion optical properties of radioactive ion beams produced with fission-, light-ion fusion and heavy ion fusion ion guides. The performance of the device has been tested in off- and on-line conditions. It has been shown that the emittance and energy spread of the ion beam can be decoupled from the ion guide parameters with high transmission efficiency.     

Ion flux from the cathode region of a vacuum arc

The properties of the ion flux generated in a vacuum arc are reviewed. The structure and distribution of mass erosion from individual cathode spots and the characteristics of current carriers from the cathode region at moderate arc currents are described. An appreciable ion flux (~10% of the total arc current) is emitted from the cathode of a vacuum arc. This ion flux is strongly peaked in the direction of the anode, although some ion flux may be seen even at angles below the plane of the cathode surface. The observed spatial distribution of the ion flux is expressed quite well as an exponential function of the solid angle. The ion flux is quite energetic, with average ion potentials much larger than the arc voltage, and generally contains a considerable fraction of multiply charged ions. The average ion potential and ion multiplicity increase significantly for cathode materials with higher arc voltages but decrease with increasing arc current for a particular material. The main theories concerning ion acceleration in cathode spots are the potential hump theory and the gas dynamic theory. Experimental data indicate that these theories serve reasonably well when used to predict the mean values of the charge state, ion potential, and ion energies for the ion flux, but are quite insufficient when compared with the results for the potentials and energies of individual ions     

表面凹陷对等离子体浸没离子注入均匀性的影响

利用二维流体模型和数值计算方法模拟了等离子体浸没离子注入（ＰⅢ）Ｋ ,具有圆弧凹槽的平面靶周围的鞘层扩展情况,计算了鞘层扩展过程中的电热分布、离子速度和离子密度变化获得了沿靶表面的离子入射角度和注入剂量的分布情况,为等离子体浸没离子注入处理复杂形状靶提供了理论基础。     

Dose regularities under ion bombardment of solids

Among other parameters which influence various processes associated with ion bombardment of solids (such as sputtering, secondary electron emission, ion scattering and so on) there is “ion dose”. As the ion dose the product of ion current density (or total ion current) and time of irradiation is usually accepted. However, this definition is valid in such cases only when the time interval required for the actual experiment (or for the actual measurement) is small as compared with a certain time interval (relaxation time) which may be approximately determined as the bombarded ion penetration depth divided by the velocity of the irradiated surface motion due to target sputtering. The examination of the situations which take place in typical ion bombardment experiments (ion current densities of about 0.01–1.00 ma/cm², sputtering ratios of about 1–10 at/ion) shows that the relaxation time turns out to be of the order of some minutes to some seconds depending strongly, in particular, on the crystalline target orientation with respect to the ion beam direction. When the time interval required for the performing of the experiment exceeds considerably the relaxation time the critical ion dose must be determined as the product of ion current density and the relaxation time. In fact, the damaged layer of the irradiated target is continuously sputtered and this process prevents the accumulation of damage. Because the relaxation time is inversely proportional to the bombarding ion current density in this case the critical ion dose proves to be independent of ion current density. This peculiar fact must be taken into account in particular when the dependence of various characteristics of the ion-solid interaction process upon bombarded ion current density are analysed. When the time interval during which the measurements are performed is comparable with the relaxation time one can expect that transient characteristics must be observed. In particular they must be observed when an abrupt change of irradiated crystalline target orientation with respect to the bombarded ion beam is performed.     

稀土探针Sm3+与牛血清白蛋白结合作用的分子光谱及电化学表征

研究了稀土Sm3 与牛血清白蛋白 (BSA)固体配合物合成方法 ,对其傅里叶红外光谱分析表明 ,Sm3 与牛血清白蛋白的羟基的氧和胺基或酰胺基的氮形成强烈的配位配合物。紫外光谱分析表明 ,Sm3 与BSA作用时直接与酪氨酸残基作用。在模拟生理条件下研究了Sm3 与BSA的结合性质 ,荧光光谱分析表明Sm3 与BSA形成 2 5∶1的配合物 ,表观络合常数为lgK =11 0 0。并用循环伏安法研究了pH条件对Sm3 与BSA结合作用的影响以及该配合物的稳定性     

兰州重离子加速器冷却储存环中电子冷却性能

为了在兰州重离子加速器冷却储存环(HIRFL-CSR)上开展一维离子束序化的研究,在CSR主环上,对6.39 MeV/u的58Ni19+离子束进行了冷却累积实验。测量了离子束与电子束之间不同的水平、垂直夹角以及不同电子束剖面的情况下,束流累积及束流寿命变化情况;重点研究了离子束衰减过程中动量分散随离子数的变化规律,拟合计算得到了动量分散随离子数按照幂函数衰减的指数;在给定离子数的情况下,动量分散随夹角、电子束剖面的依赖关系,为下一步在CSR上获得纵向一维有序化离子束的研究做准备。在实验中观测到在较大的夹角情况下,离子束出现纵向振荡和中心频率移动。     

中子管用潘宁离子源氢负离子产生机理及实验研究

为了克服目前潘宁(PIG)离子源中子管引出正离子所带来的诸多不利因素,使用PIG型氢负离子源作为中子管的离子源,研究了氢负离子产生的机理,以期在中子管中获得应用。给出了PIG离子源结构,根据氢负离子产生的方式和条件,结合CST软件仿真实验,确定在对阴极和引出孔附近区域存在氢负离子,而且是氢负离子密度比较大的区域。实验中,通过负离子源产生系统证实了氢负离子的存在及分布规律,中子监测仪测量自成靶50mm负离子源陶瓷中子管,中子产额较传统正离子中子管高出一个数量级以上。     

多峰离子源的三维数值模拟优化与设计

本文理论计算了多峰离子源永磁体, 采用二体碰撞模型处理电子之间的库仑碰撞, 运用空碰撞方法处理电子与氢元素相关粒子碰撞, 开发了全三维粒子模拟-蒙特卡罗模拟算法, 并采用此软件对热门多峰离子源JET-60U的两种优化设计模型进行数值模拟研究, 探索了两种离子源空间分布特性和体积负氢离子产率相关问题, 提出了负氢离子源设计的基本思想: 适当调整离子源多峰磁场分布情况可以输出均匀离子束; 适当调整引出磁场大小和离子源结构, 可以达到离子束空间均匀性和高产率兼顾的效果.     

EAST H模等离子体中离子内部输运垒特性 的初步实验研究

为了研究EAST上H模等离子体中离子内部输运垒(ITB)的特性，利用电荷交换复合光谱诊断，分析了离子ITB形成和稳态阶段等离子体离子温度和环向旋转速度的时空演化。结果表明，在离子ITB形成和稳定期间，ITB肩部附近(R=1.928m)的离子温度梯度增加时，ITB区域(R=1.984m)的离子温度梯度会有所降低，反之亦然。考虑到在离子ITB形成前，芯部区域不同半径位置的离子温度梯度同时增加或减小，得到了在R=1.984m处判断离子ITB是否形成的归一化离子温度梯度的阈值。     

Photoluminescence in europium ion–substituted bismuth niobate particles

In order to understand the influence of the substitution of europium ion for bismuth ion in the structural and photoluminescence properties of bismuth niobate, bismuth niobate ceramic powders, with different amount of europium ion, were prepared using sol–gel citrate route. The structural and morphological studies were made with X-ray diffraction, Raman, and scanning electron microscopy measurements. Rietveld’s analysis of X-ray diffraction proves the formation and increment of europium niobate phase in europium ion–substituted bismuth niobate samples with increase of europium ion concentration. Photoluminescence results also concur to that of X-ray diffraction and Raman with gradual swapping of europium ion emission from one phase to the other phase at higher concentration.     

Depth control of a silicon structure fabricated by 100q keV Ar ion beam lithography

Ion beam lithography of a silicon surface using an Ar ion beam with an ion energy in the order of hundreds of keV is demonstrated in this study. A specially designed ion irradiation facility was employed that enabled generation and irradiation with a highly accelerated and highly charged Ar ion beam. An ion-beam-induced amorphous layer on a silicon substrate can be selectively etched in hydrofluoric acid, whereas, a non-irradiated area is scarcely etched and, consequently, a concave structure can be fabricated on the irradiated area. To control the depth of the structure, parameters for dependence of the depth on ion irradiation were investigated. As a result, the depth of irradiated area can be controlled by the ion energy that is adjusted by the acceleration voltage and the ion charge. In addition, the etch resistance of the irradiated area increases with an increase in ion energy due to the crystalline layer formed on the surface. Simulation results reveal that the depth is strongly related to the defect distribution induced by ion irradiation. These results indicate the potential use of this method for novel three-dimensional lithography.     

Broad Beam Gas Ion Source with Hollow Cathode Discharge and Four-grid Accelerator System

1 Introduction Ion sources with wide energy and current ranges are used extensively in industrial applications such as ion implantation, etching, and deposition. Broad beam ion sources with a uniform current distributions are needed for many industrial applications and development of commercial ion bean technologies for surface modification of materials is impossible without highly efficient, simple, and dependable ion sources. These and other needs have spurred the development of high efficiency ion sources that can produce ion beams with high energy and current and require low or no maintenance.     

一台小型强流脉冲离子束加速器

 介绍了一台小型强流脉冲离子束加速器的结构组成,采用箍缩反射型离子二极管,可以稳定工作的峰值电压为200kV,得到了峰值为1.5kA、脉宽约20ns的离子束流,平均离子流密度110A/cm²。     

非对称离子门控制方法和对离子迁移谱分辨率的改善

为了改进离子门的驱动方式,简化离子门驱动电源设计和提高离子迁移谱分辨率,通过增加一组电阻实现离子门两端的不对称供电,再对低电压端的电压进行控制实现离子门功能。分析了该方式下的两种情况对迁移管内的电场、离子迁移谱的分辨率和信噪比的影响。借助SIMION7.0对离子门两边的电场分布进行了模拟和比较,并应用数值化拉普拉斯方程的方法计算了迁移管轴线的电场数据。实验证明：相比常规迁移谱的离子门浮地驱动电源,这种驱动方法成本低,离子门电源的设计简单,能够明显提高离子迁移谱的分辨率。该方法能够应用于离子迁移谱的测量仪器或实验设备。     

ECR离子源引出束流周期性波动研究

Earlier we reported an ion current jump which was observed at a fixed negative biased disc potential in the 6.4GHz ECR ion source at VECC,Kolkata.In a recent experiment with neon ions,we measured the time spectra of the ion current and observed the presence of a burst frequency in the kilohertz range.This frequency shows a correlated jump with the ion current jump described above.Another interesting feature is that the observed burst frequency shows a good linear correlation with the extracted ion current.The higher the ion current,the higher is the burst frequency.This means that current per burst is a constant factor;when there are more number of bursts,the current also increases.     

Optimisation of cold cathode ion source model

This paper represents the results of the optimisation of cold cathode ion source model with 5 cm extraction aperture diameter. In this model, the glow discharge is utilised for generation of electrons in the cathode of the ion source. The various models with different lengths of cathode and anode are tested. The shortest model with 4.5 cm in length of cathode and anode each shows satisfactory operation and can be used in cases when the high values of extracted ion current are not required. The best model from the point of view of ion beam current value and efficiency of the discharge is the model with cathode length of 7 cm and anode length of 7 cm. In this case, the obtained maximum ion beam current is 110 mA when the discharge current is 1000 mA. In case when moderate values of extracted ion beam current are necessary, it is possible to operate the ion source even without the anode magnetic system.     

Polarized ion sources: Status and perspectives

Modern polarized ion sources generate polarized ion beams with high intensity and polarization. Mainly, atomic beam-type and optically pumped polarized ion sources are used to provide polarized ion beams to accelerators. Principles of both methods are outlined in the paper. Characteristics as well as possible improvements of polarized ion sources are considered.     

Ion pair formation in the vacuum ultraviolet region of NO studied by negative ion imaging spectroscopy

The pair formation of positive and negative fragment ions has been studied in the vacuum ultraviolet region of NO, with negative ion imaging spectroscopy. The negative ion yield curve obtained in the photon energy region of 19–25 eV exhibits many structures which are absent from the photoabsorption spectrum in the same region. The partial yields and asymmetry parameters associated with the dissociations into individual ion pair limits have been extracted from the negative ion images observed. On the basis of these quantities, the assignments for the structures exhibited on the negative ion yield curve are given and the dynamical properties on the ion pair dissociation are discussed.     

表面离子阱的衬底效应模型研究及新型离子阱设计

通过分析表面离子阱衬底的功率损失和电势损失对离子阱阱深和离子加热速率的影响,提出考虑衬底效应的阱深和离子加热速率的解析分析模型.研究发现,硅基衬底的电势损失对表面离子阱阱深的降幅达17.19%,功率损失对离子加热速率的加速达13.37%.为了降低衬底效应的不利影响,设计了衬底真空隔离结构的表面离子阱,在离子阱射频电极和直流电极间的衬底表面刻蚀出多条隔离槽,从而减小衬底的等效电导和等效电容,达到降低衬底功率和电势损失的目的.模拟结果显示,相比于一般结构,真空隔离结构的硅基表面离子阱能够使阱深加深20.22%,使衬底功率损失降低54.55%.