Penning阱中离子运动的分析

根据Penning离子阱结构及电磁场分布特点,列出阱内离子运动方程并进行求解,对其中沿z轴运动和在xy平面上的运动进行详细分析,最后得到比荷为m/q的离子在Penning阱内的运动为沿磁场方向的简谐振动、绕磁感线旋转的回旋运动和垂直于z轴及径向绕z轴的漂移运动的叠加.     

Paul阱中存储离子的研究

根据Paul离子阱结构及电场分布特点,列出阱内离子运动方程并求解,对其中离子运动、硅团簇离子碰撞解离反应进行了分析.     

Secondary ion emission from Si under nitrogen ion bombardment

The yield and energy distribution of positive secondary ions emitted from Si under N₂⁺ ion bombardment were measured. The obtained mass peaks correspond to three types of secondary ion species, that is, physically sputtered ions (Si⁺, Si₂⁺), chemically sputtered ions (SiN⁺ Si₂N⁺) and doubly charged ions (Si²⁺). The dependence of secondary ion emission on the primary ion energy was studied in a range of 2.0–20.0 keV. The yields of physically and chemically sputtered ions were almost independent of the primary ion energy. The yield of the doubly charged ion strongly depended on the primary ion energy. The energy distribution of secondary ions of the three types showed the same dependence on the primary ion energy. The most probable energy of the distribution increased with the primary ion energy. On the other hand, for the energy distribution curves of sputtered ions, the tail factors N in E^?N were constant and showed a m/e dependence.     

Characteristics of electrical field and ion motion in surface-electrode ion traps

In this article, we calculated the potential function of the surface-electrode ion trap (SEIT) by using Green's function method, optimized trap size, obtained the coefficients of the multipoles and analyzed ion trajectories in the RF potential. The optimized SEIT not only increases its trapping well depth by a factor of about 15, but also has relatively good linearity of the field (or large quadrupole component). The current design of SEIT can work well either as the ion guide for ion transmission or as the ion trap for ion confinement. Our research can be used to calculate the potential function in the SEIT with different device parameters, understand ion motions in the traps and optimize instrument performance. The method for calculating potential function can be expanded to planar and halo ion traps.     

Penning阱中Hn+团簇离子的检测与确认

报道了在Penning阱中检测与确认Hn 团簇离子的方法,介绍了离子在阱中的运动,重点分析了离子存储条件、离子的产生与探测、离子信号的放大与检波以及离子谱的分辨.     

Paul阱中离子运动及稳定性分析

Paul离子阱由于没有外加磁场所引起的塞曼效应的影响,已成为离子存储及研究离子的重要装置.根据在实验中所采用的Paul离子阱结构及电场分布特点,列出阱内离子运动方程并进行求解,对其中各种运动进行分析,同时还分析了离子存储稳定性.最后对所作的研究进行总结,得到如下结论:阱中离子的运动为谐振运动、基频微运动和高阶微振动.     

Secondary ion mass spectrometer based on a high-dose ion implanter

A secondary ion mass spectrometer built around a modified high-dose ion implanter is used to study secondary ion emission in metals over a wide range of primary beam energies. The implanter generates ion beams with energies of up to 150 keV and a substrate current to 30 μA. A modified MX7304A monopole mass spectrometer is applied as an analyzer of secondary ions with mass numbers of up to 400 with a resolution of 1 M at a level of 10% of the peak height. The detection limit for iron is 6.5 ppm. The analyzer is equipped with a small-size filter separating secondary ions in energy. The relative emission intensities of the secondary monatomic and cluster ions of copper for different primary ion beam parameters are studied.     

Influence of ion species ratio on grid-enhanced plasma source ion implantation

Grid-enhanced plasma source ion implantation (GEPSII) is a newly proposed technique to modify the inner-surface properties of a cylindrical bore. In this paper, a two-ion fluid model describing nitrogen molecular ions N_2^+ and atomic ions N^+ is used to investigate the ion sheath dynamics between the grid electrode and the inner surface of a cylindrical bore during the GEPSII process, which is an extension of our previous calculations in which only N_2^+ was considered. Calculations are concentrated on the results of ion dose and impact energy on the target for different ion species ratios in the core plasma. The calculated results show that more atomic ions N^+ in the core plasma can raise the ion impact energy and reduce the ion dose on the target.     

Influence of ion-beam plasma on ion extraction efficiency in a single-grid ion source

The influence of ion-beam plasma on ion extraction efficiency in a single-grid ICP ion source is researched. The single-grid ion source is considered as a system with two plasmas, ion-beam plasma and the source plasma, separated by an extraction grid. Results of experimental measurements of the potentials of the two plasmas and the ion beam current dependence on these potentials are presented. It is shown that the ion extraction efficiency depends equally on both the acceleration potential and on the potential of the ion-beam plasma. The obtained results demonstrate the key role of the ion-beam plasma in the ion source operation, which is important in technological applications and space thrusters.     

Low-temperature ion emission

Technical Physics - The kinetics of alkali metal ion emission from metal surfaces heated to temperatures of 800–2500 K is studied. The ion current relaxation is described by the relationship...     

射频离子源离子束成分光谱测量

为HL-2A 装置中性束注入器研制了引出束功率为1MW 的射频离子源。在测试平台上,实验离子源已经成功引出了束能量和束电流分别为35keV 和12.4A、束质子比为79%、脉宽为100ms 的氢离子束,达到了设计束功率要求的44%。在射频离子源实验平台上,利用多普勒频移光谱方法测量了离子源引出束流成分比例,对比了束流成分和射频离子源引出束流之间的关系。实验数据分析表明,在10A 引出束流的情况下,离子流成分 H⁺ ₁、H⁺ ₂ 和H⁺ ₃ 分别为75%、18%和7%。并且当引出束流从3.3A 升至10.4A 时,H⁺ ₁ 从37%升至78%,而H⁺ ₃ 则从19%降至9%。     

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%.     

铪离子等离子体源离子注入铜基体的数值模拟

通过SRIM软件对铪离子等离子体源离子注入铜进行了模拟。模拟了铪离子注入铜的核阻止本领、电子阻止本领、入射深度随能量的变化,以及在不同注入条件下铪离子的摩尔浓度分布,并对模拟结果进行了分析。结果显示：能量低于6 MeV时核阻止本领占主导地位,高于6 MeV时电子阻止本领成为主要的能量损失,并且离子注入过程中会出现能量沉积的Bragg峰和质量沉积区域较集中的现象,入射深度随能量的增加而增加。     

铪离子等离子体源离子注入铜基体的数值模拟

通过SRIM软件对铪离子等离子体源离子注入铜进行了模拟。模拟了铪离子注入铜的核阻止本领、电子阻止本领、入射深度随能量的变化,以及在不同注入条件下铪离子的摩尔浓度分布,并对模拟结果进行了分析。结果显示:能量低于6 MeV时核阻止本领占主导地位,高于6 MeV时电子阻止本领成为主要的能量损失,并且离子注入过程中会出现能量沉积的Bragg峰和质量沉积区域较集中的现象,入射深度随能量的增加而增加。     

单个心肌细胞中随机钙火花诱发的钙离子螺旋波

利用改进的描述单个心肌细胞内钙信号的离散的fire-diffuse-fire模型和相分析方法, 模拟研究了钙火花随机释放特性对钙离子螺旋波的诱导激发作用, 研究结果表明, 适当频率的钙火花可以在静息心肌细胞中诱导产生钙离子螺旋波; 时序和空间不同的钙火花引起的相奇点的出现, 是产生螺旋波的关键; 系统相奇点的个数与钙火花频率相关, 并且对于固定系统有极限值.     

Nonlinear rotary wave ion plasma

The nonlinearly coupled Vlasov-Maxwell ion-plasma field equations are solved exactly for a transversely uniform subgroup of rotational modes induced by a uniform axial magnetic field. The ion orbits in momentum space are bipolar doubly periodic eigenfunctions of ion proper time, obtained in closed form as the difference between two doubly quasi-periodic Weierstrass zeta functions. The ion orbits in position space are helical-spiral doubly quasi-periodic functions of ion proper time, expressible simply in terms of doubly quasi-periodic Weierstrass sigma functions. The complete ion distributions are flexible functions of six constants of the ion motion: wave-frame ion energy, transverse gyro center, an inner Hamiltonian correlating wave-frame ion momentum with wave-frame axial position, and both first and second axial integration constants. A rotary electromagnetic plane wave propagates along the axial magnetic field with complex cisoidal dependence upon wave-frame axial position. The eigenvalue determination intricately interrelates the wave propagation vector, the wave amplitude, the axial magnetic field, the double periods, and the bipole separation.     

Scanning helium ion microscope: Distribution of secondary electrons and ion channeling

The principles and features of operation of a scanning helium microscope are reviewed briefly. The measurement data on the energy distribution of secondary electrons excited by the ion beam in an Au film and on the angular dependence of the backscattered ion yield are obtained and presented for the first time. The effect of ion channeling in silicon single crystal with the (110) orientation is demonstrated.     

Development of arc ion sources for heavy ion fusion

An overview of the development of arc ion sources for heavy ion fusion is presented. Two approaches to heavy ion fusion (HIF)-the RF linac-storage ring approach and the induction linac approach-are described. RF linac schemes require low emittance and moderate current levels, because the beam is accumulated in storage rings before being focused on target. The induction linac approach requires low emittance and high current, because this is a single-pass approach to HIF and one wishes to limit the number of beams in the machine. The RF scheme generally uses long pulse sources together with a buncher of RFQ. The induction linac approach requires sources in the microsecond pulse length range, with good optics being maintained during the pulse. Emphasis is on the induction linac approach pursued at the Lawrence Berkeley Laboratory     

Optimum electrode configurations for fast ion separation in microfabricated surface ion traps

For many quantum information implementations with trapped ions, effective shuttling operations are important. Here, we discuss the efficient separation and recombination of ions in surface ion trap geometries. The maximum speed of separation and recombination of trapped ions for adiabatic shuttling operations depends on the secular frequencies the trapped ion experiences in the process. Higher secular frequencies during the transportation processes can be achieved by optimising trap geometries. We show how two different arrangements of segmented static potential electrodes in surface ion traps can be optimised for fast ion separation or recombination processes. We also solve the equations of motion for the ion dynamics during the separation process and illustrate important considerations that need to be taken into account to make the process adiabatic.     

Microfabricated ion traps

Ion traps offer the opportunity to study fundamental quantum systems with a high level of accuracy highly decoupled from the environment. Individual atomic ions can be controlled and manipulated with electric fields, cooled to the ground state of motion with laser cooling and coherently manipulated using optical and microwave radiation. Microfabricated ion traps hold the advantage of allowing for smaller trap dimensions and better scalability towards large ion trap arrays also making them a vital ingredient for next generation quantum technologies. Here we provide an introduction into the principles and operation of microfabricated ion traps. We show an overview of material and electrical considerations which are vital for the design of such trap structures. We provide guidance on how to choose the appropriate fabrication design, consider different methods for the fabrication of microfabricated ion traps and discuss previously realised structures. We also discuss the phenomenon of anomalous heating of ions within ion traps, which becomes an important factor in the miniaturisation of ion traps.