冷阴极潘宁离子源通过表面溅射直接引出负离子

在不引入铯蒸汽的情况下，对袖珍型永磁冷阴极潘宁离子源通过固体表面溅射的方式，直接引出氯、溴等元素的负离子进行了初步研究。利用该源，在气耗量小于２０ｃｍ３／ｈ、弧功率约５０Ｗ的情况下，除了从放电气体中直接引出相关元素的负离子外，分别以ＮａＣｌ、ＮａＢｒ、ＮａＦ为阴极靶材，通过表面溅射，在传输效率为１５％时，得到相应元素的负离子分析束Ｆ－６０μＡ、Ｃｌ－６８μＡ、Ｂｒ－３９μＡ。实验中观测到，不同的辅助工作气体对固体表面溅射形成负离子的产额有一定的影响。     

射频负离子源关键参数测量系统研制

强流离子源是大功率中性束注入系统的关键部件之一,为了实现中性束注入系统的稳态运行,需要开展射频负离子源的实验研究。射频负离子源的负离子引出电流、引出总电流和引出电子流等关键参数的测量是射频离子源实验理论分析的基础,本系统通过信号调理隔离传输实现射频负离子源关键参数的测量。实验结果表明,系统测量采集数据精准可靠,运行稳定。     

溅射负离子源的最新发展

负离子源是应串列加速器的需要而产生的。目前在串列加速器上基本上使用三种形式的负离子源——双等源、电荷交换源和溅射源。双等源在产生束流品质较好的气体负离子方面有特殊的优点。它能产生多种气体负离子,如氢、氘、碳、氮、氧、氟等,而且束流较大,发射度较小。如通用离子源公司的358型双等源,能给出最大的氢负离子流约150μA,发射度约3～6mm·mrad·MeV~(1/2)。电荷交换源也不可缺少,目前它是产生氦负离子的唯一离子源。通用离子源公司生产的710锂电荷交换源能保证4μA的氦负离子,2μA的锂负离子。溅     

永磁端引出溅射PIG源进展

介绍了永磁端引出溅射ＰＩＧ离子源的进展状况，通常它可用于引出气体的与金属的单或多电荷离子，在２０－３０ｋＶ的引出电压下，可引出ｍＡ级的气体离子和数十微安的金属离子，功耗小于５０Ｗ。同时也可用于直接引出某些电子亲合势料强的气体元素，如，Ｈ，Ｏ，Ｆ等的负离子。     

加速器质谱测量136Sn的负离子引出实验研究

许多核素的同量异位素不能形成负离子或形成的负离子不稳定,可借助于此来有效消除同量异位素干扰,这是串列AMS的优点之一。此外,AMS测量中选用某种化合物形式引出相应负离子时,其干扰核素不能形成负离子或者束流很小,这样,即可在离子源处压低同量异位素的干扰,从而可提高测量灵敏度。因此,样品化学形式及引出负离子的选择在AMS测量中是非常重要的。     

微波驱动离子源的恢复

2008年底,在加拿大TRIUMF国家实验室工作期间恢复了1台微波驱动离子源。这台离子源能产生稳定可靠的正离子和负离子,可用于回旋加速器和其他种类的加速器。目前,该离子源在频率2．45GHz、输入功率500W情况下,产生2．1mA的负氢离子,束流归一化发射度0．25nmm·mrad。     

用ZhT-1301型质谱计进行微量铅的同位素分析试验

我们的任务是试图解决分析样品中微克量级铅的同位素级成的问题,使用的仪器是中国科学院科学仪器厂生产的ZhT-1301型质谱计。一、实验方法1.方法选择固体元素的同位素分析,一般多采用带状离子源进行,因为这种类型的离子源较其它类型     

在线Nielsen源的研制

描述如何简单地把标准Ｎｉｅｌｓｅｎ源必建成在线离子源，对它的一些性能进行测试并与标准离子源作了比较，讨论了它们的判别和产生的原因。实验结果表明，两离子源的放电特性无差别，改建后的离子源可考虑用来进行整体靶离子源试验。     

低能强流负氢束发射度测量仪的设计

随着核物理实验、原子物理、表面物理实验的进一步发展以及加速器技术在各领域的广泛应用，对离子源产生的束流品质的要求也越来越高。束流发射度是束流品质的一个重要指标，因此，对离子源束流发射度的测量和研究，对离子源技术本身、加速器研究以及相关应用技术都具有重要意义及参考价值。     

用于溅射负离子源的透射表面电离器的研制

介绍了１种应用于表面电离型溅负离子源的球面形透射表面的电离器，并阐述了原理。这种电离器可使铯蒸气直接通过，避免了铯蒸气绕射造成电离表面铯原子通量低的缺点，增大了铯离子的产额也使离子源的流强较采用非透射型电离器时提高了５０－８７％。‘     

Hefei utility negative ions test equipment with RF source: commissioning and first results

In order to study the key technology and physics of RF driven negative ion source for neutral beam injector in China, the Hefei utility negative ions test equipment with RF source was developed at Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). Its negative ion source can be equipped with single or double RF drivers. There is a plasma expansion chamber with depth of 19 mm and an enhanced filter field. A three electrodes negative ion accelerator was employed to extract and accelerate the negative ions, which are plasma grid, extraction grid and ground grid. And there are several diagnostic tools for the plasma and beam parameters measurement. The characteristics of plasma generation, negative ion production and extraction were studied on the test equipment. The negative ion beam was extracted from the RF driven negative ion source for the first time. The detailed structure and main results are presented in this article.     

Power Consumption in Positive Ion Beam Converter with Electrostatic Electron Suppressor

The power recovery characteristics of an in-line direct beam converter provided with electrostatic electron suppressor were studied numerically by tracing the orbits of fast primary ions and secondary charged particles generated along their beam path by collision with background gas molecules. It is shown that, in reference to the electrostatic field potential at the point of impact, the energy distribution of secondary ions impinging on the suppressor has two peaks—one corresponding to a zone of high positive potential surrounding the collector and the other to one of slightly negative potential around the electron suppressor. Secondary electron emission from the suppressor is ascribed mainly to the latter peak, associated with impingement of slower secondary ions. Far much power consumed in secondary particle acceleration is spent for emitting electrons from the suppressor than for secondary ions generated by beam-gas collision. The upper limit of background pressure is discussed on the basis of criteria prescribed for restricting the power consumed in this secondary particle acceleration, as for practical convenience of electrode cooling. Numerical examples are given of calculations based on particle trajectory analysis of both primary ions and secondary particles, for the case of a 100 keV-proton sheet beam 10 cm thick of 35mA/cm² current density.     

中子管用PIG负氢离子源及其束流引出实验研究

PIG离子源用于中子管引出正离子,但在使用过程中存在一定问题,如单原子离子比低、靶材料溅射严重及功耗大等。为解决这些问题,提高中子管的寿命和稳定性,本文设计一种中子管用PIG负氢离子源,并对其束流引出进行实验研究。分别测量了离子源的磁场、不同阴极材料及引出阴极离子发射孔径对引出负氢离子束流的影响。实验数据表明,该负氢离子源可用于制作性能指标良好的中子管。     

On the understanding of positive and negative ionization processes during ToF-SIMS depth profiling by co-sputtering with cesium and xenon

In this paper, ionization processes of secondary ions during ToF-SIMS dual beam depth profiling were studied by co-sputtering with 500 eV cesium and xenon ions and analyzing with 25 keV Ga⁺ ions. The Cs/Xe technique consists in diluting the cesium sputtering/etching beam with xenon ions to control the cesium surface concentration during ToF-SIMS dual beam depth profiling. Several depth profiles of a H-terminated silicon wafer were performed with varying Cs beam concentration and the steady state Si, Xe and Cs surface concentrations were measured in situ by Auger electron spectroscopy. It was found that the implanted Cs surface concentration increases with the Cs fraction in the beam from 0% for the pure Xe beam to a maximum Cs surface concentration for the pure Cs beam. Secondly, the variation of the silicon work function, due to the Cs implantation, was measured in situ and during depth profiling as the shift of the secondary ion kinetic energy distributions. Finally, the positive and negative elemental ion yields generated by the Ga analysis beam were recorded and modeled with respect to varying Cs/Xe mixture. We found that the Si⁻ and the Cs⁻ yields increase exponentially with the decrease of the silicon’s work function while that of Cs⁺ and Si⁺ decrease exponentially, as expected by the electron tunneling model.     

Progress of the RF negative hydrogen ion source for fusion at HUST

Huazhong University of Science and Technology has developed an experimental setup of a radio frequency (RF) driven negative hydrogen ion source, to investigate the physics of production and extraction of the H− ions for neutral beam injection in nuclear fusion reactors. The main design parameters of the ion source are: RF power ≤40 kW; extraction voltage ≤10 kV; accelerator voltage ≤20 kV. This paper gives an overview of the progress of the ion source with particular emphasis on some issues. The RF driver and source plasma are analyzed and optimized in terms of impedance matching, plasma characteristics and power coupling. In regard to the simulation analysis, a plasma model based on the particle-in-cell method and a beam trajectory model considering beam stripping loss are developed to investigate the plasma and negative ions transport inside the ion source. Furthermore, a collisional radiative model of H and H2 is built for plasma optical diagnosis.     

Symmetric Neutralized Ion Beams for Magnetic Fusion Applications

A symmetric neutralized ion beam (SNIB) is composed of positive and negative ions, and is capable of propagating across a transverse magnetic field due to the polarization of the beam. Such a beam may be of use as an alternative or complement to conventional neutral beam injection (NBI) in magnetic confinement fusion devices. SNIBs of energies from hundreds of keV up to a few MeV can be efficiently produced through a novel application of radio frequency quadrupole (RFQ) accelerators. Because the cross-field propagation ability of the SNIB depends mainly on beam density, SNIBs of significantly lower energy than the 1 MeV envisioned for ITER neutral beams can in principle reach the center of a magnetically confined plasma. Some challenges that need to be overcome for this technique to be viable are identified; nevertheless, the approach is attractive when compared to the bulky, high voltage, conventional neutral beam systems. Distributed injection of many beams is possible due to the relative compactness of a SNIB module.     

Collection, cooling and delivery of ISOL beams

The collection of an ISOL beam in a Penning trap using implantation on a surface that is subsequently manipulated so as to become part of an end electrode of a Penning trap and reionization of the implanted material by heat has already been very productive for high-precision nuclear-mass measurements, even though it is limited to elements that are surface ionizable and the collection efficiencies are never better than about 0.1%. More recently, in 1990 a Paul trap system for electric collection of ions was installed at the ISOLDE-3 facility and collection was demonstrated for a 60 kV beam of ¹³²Xe ions. The purpose of this test setup was to determine the relationship between phase space volume of a typical trap and the collection efficiency that could be obtained in direct capture. For the modest trap used, collection efficiencies of up to 0.2% were achieved. A beam of negative bromine ions was collected by simply reversing the polarities of all voltages used. From the experience with this system it appears feasible to build a Paul trap which is about three times as large in linear dimensions as the existing one and which could be driven at up to 10 kV peak at 1 MHz using a modest rf amplifier (300 W). With moderate prebunching of the injected beam at 1 MHz, this system should achieve collection efficiencies approaching 100%. Based on these results, preliminary design work is being carried out on the collection system to be installed at the ISOLDE Booster facility. Suggestions for other uses of a Paul trap collection system for ISOL beams are presented.     

RFQ加速装置同时加速同荷质比正负离子的理论与实验研究

提出用RFQ加速器同时加速同荷质比正负离子的理论,并利用现有的RFQ加速装置进行了实验验证。初步结果表明：采用这一方法可有效提高RFQ加速装置的载束能力。     

静电加速器离子束杂质成分的测定

静电加速器广泛应用于离子的X射线分析、背散射、核反应和研究离子与物质的相互作用等等。静电加速器的离子由离子源产生,极端部高压进行加速。离子源所产生的离子往往不是很纯净的。为此,通常依靠磁分析器来排除那些被加速而又不需要的离子,并挑选出所需要的离子。但是,磁分析器要区分开那些荷质比相近的离子是十分困难的。在磁分析器所挑选出的离子束中,往往含有一些荷质比相近的其他离子。例如,在选择氘离子源的D~-离子中伴随有H_2~ 离子;相反在选择氢离子源的H_2~ 离子却伴随有D~ 离子。~4He~ 离子中可能伴随D_2~ 和~(12)C~(3 )离子。离子束中的杂质成分往往被人们所忽视,但在有些情况下,却是不容忽视的。例如,在利用D~ 离子分析表面氢含量时,D~ 离子束中含有H_2~ 离子就会直接影响到分析的灵敏度;在研究H_2~ 离子与固体膜相互作用时,H_2~ 离子中含有的D~ 离子的数量大小也会影响到测量的精度;在背散射分析、离子溅射、辐照损伤研究以及核反应截面测量时,有时也不能忽视离子束中的杂质成分。     

The surface charge effect by using boron ions implantation in p-channel MOSFETs fabricated

This article reports on the effects of surface charge on bare wafers and p-channel MOSFETs by a positive ion beam accompanied by an electron beam current for surface charge neutralization. Without the negative electron beam the films show a higher sheet resistance and the pMOSFETs exhibit a lower threshold voltage, a lower breakdown voltage and a lower gain factor. If the electron beam current is equal to or higher than the ion beam current of 6 mA, the uniformity of sheet resistance, fluctuations of breakdown voltage and gain factor are significantly improved by controlling the charge neutralization in this experiment. It prevents the positive charges from penetrating the poly-gate and causing catastrophic damage in the gate oxide layer. The sheet resistance deviation for the samples with a capped photoresist is higher than that for the bare wafer because the insulating property of the photoresist enhances the wafer surface charge accumulation and thus repels the subsequently implanted ions. The thinner gate oxide layer leads to larger deviations of threshold voltage, breakdown voltage and gain factor due to the imbalance of surface charge.