低能高束流氩离子源的结构及性能

离子源技术是等离子体研究中的一项重要内容,而低能大束流源则是离子源技术研究中的一个重要方向,因为这样的源在离子束刻蚀、离子束溅射镀膜以及荷能粒子与物质相互作用方面都有广泛的应用;本文采用空心阴极空心阳极结构,用热阴极电子发射弧放电驱动并用磁场约束产生等离子体,用曲面发射引出离子束,研制成了氩气放电溅射离子源;研究了灯丝加热电流、弧压对弧流的影响和弧流与工作气体压力对离子束引出的影响规律.离子源的引出电压在0-4.0 kV之间连续可调,最大引出束流为100 mA,束斑面积为φ6.0 cm,以Ti为溅射靶时的最大溅射沉积率为0.45 nm/s,离子源可连续工作160 h.     

真空弧离子源引出束流在加速空间的分布

采用数码相机直接照相的方法来确定真空弧离子源引出束流在加速空间的分布。实验在动态真空实验系统中进行,系统真空度优于2×10-3 Pa。在离子源脉冲工作的条件下,采用数码相机拍摄到离子源引出束流在加速空间的积分图像,得到引出束流的幅亮度在拍摄平面上的相对分布,然后再通过Abel转换得到引出束流在加速空间的径向分布。实验结果表明:真空弧离子源引出束流近似高斯分布,离子源出口处的束流比靶入口处的束流强40%。     

强流ECR离子源研究进展

研制了一台用于强流质子加速器的强流ECR离子源,建立了无油、大抽速的离子源实验台架,解决了微波功率馈送、放电室结构、高压打火和微波窗板损坏等问题,特别是对影响离子源寿命的窗板问题,做了独创性的改进,有效地解决了窗板容易损坏的难题,获得了很好的结果。离子源的引出能量达到70 keV,最大引出束流100mA,质子比好于80％,归一化rms发射度小于0.2π mm·mrad,离子源通过了12 h连续运行的可靠性考验。另外,设计加工了用于低能束流传输段的螺旋管透镜,设计加工了束流脉冲化装置,下一步将开展低能离子束的传输特性及脉冲化研究。     

用于质子直线加速器的强流ECR离子源

介绍了正在研制的一台强流ECR离子源。它的目标是用于加速器驱动的次临界系统(ADS)。两种结构的离子源均获得了较好的结果。在30 keV能量下,氢离子最大束流达到100 mA,质子比好于85％,引出束流密度最高可达340 mA/cm2。初步测定的发射度约为0.11πmm·mrad。已通过了100 h的连续运行考验。     

反应堆上产生强流放射性核束的模拟实验装置

正研制了一台反应堆上产生强流放射性核束的模拟实验装置。模拟装置示于图1,模拟装置真空室与反应堆中子管道尺寸一致。模拟装置由真空系统、真空室、加热系统、离子源、导向器、四极透镜、束测单元等元件组成。离子源阴极采用LaB6材料,由加热元件加热发射电子,电子在阴极和阳极之间加速获得能量后在阳极内与原子碰撞将原子电离。离子源位于20kV的电位上,离子通过引出电极引出加速获得20keV的能量。紧跟着离子源,布置了一套XY导向器,然后是两组四极     

EAST-NBI离子源电极打火分析及处理

强流离子源是EAST(Experimental Advanced Superconducting Tokamak)中性束注入器(Neutral Beam Injector,NBI)最关键的核心部件,其能达到的性能在很大程度上决定了EAST中性束注入器所能达到的指标。离子源在束引出时电极打火现象偶有发生,这对于离子源的正常运行有非常严重的影响,甚至危害离子源的寿命。本文结合离子源运行过程中的束引出实验波形和水流量热计(Water Flow Calorimetry,WFC)系统的测量数据得出等离子体发射面的束流光学系统一直处于非最佳聚焦状态是导致打火的原因,试通过优化高压投入时刻等离子体与高压的匹配,实现高压的稳定投入有效抑制打火现象的发生,并且给离子源加入硬件保护机制,为离子源安全稳定运行奠定基础。     

高产额中子发生器研制

本文介绍了用于安检辐射成像的高产额中子管及中子发生器装置的主要性能指标和研发设计过程。中子管离子源采用冷阴极潘宁离子源,在引出阴极加磁钢,提高引出离子浓度。离子光学系统采用单电极加速结构,靶端通过外加电阻产生抑制电压,减小靶流,提高中子管工作稳定性。对中子管离子源和靶端通过散热结构设计和利用变压器油进行散热,效果良好。通过对中子管的各项性能参数进行测试,离子流可达50 mA以上,引出束流接近1 mA,中子产额达1.1×10¹⁰s^-1。研发的高产额中子管及发生器装置具有产额高、工作稳定、安全便携等优点,达到了设计目的。     

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。     

一台可产生直流束和微秒脉冲束的ECR离子源

ECR离子源与其他离子源相比具有一些优点。例如在放电室中具有较低的工作气压,能产生均匀的高密度等离子体,由于无热阴极可耐腐蚀气体,工作寿命长、发射度小、高原子离子比和束流强度大。所以,应用在中子发生器中具有良好发展前景。专门应用于中子发生器的ECR离子源既可引出直流离子束,又可引出微秒脉冲离子束。介绍了这种ECR离子源的工作原理和结构,给出了测量到的主要参数和脉冲波形。     

高稳定度磁控管电源

介绍ECR型离子源的磁控管稳流电源。它使磁控管输出功率稳定,保证离子源引出稳定束流。     

Modification of an Ion Source for the Production of Microampere 4He- Beams

Several modifications of the ion source of a model EN Tandem Van de Graaff Accelerator have increased the production of 4He- beams by a factor of 100 over that first obtained with the source (~10 nA). While using H2 gas for charge exchange, the replacement of the source drift tube by a screen and the installation of a system for precise adjustment of the button alignment with respect to the extractor electrode increased the output to 150 nA at the ion source. Recently potassium vapor has been used for charge exchange. Since the introduction of this technique, 4He- beam currents of 1. 2 ?A have been regularly produced. The 4He+ ions from a duoplasmatron ion source are accelerated to 20 keV and passed through the standard exchange canal which is modified by the addition of a potassium vapor chamber. Analyzed 4He++ beams of 0.3 to 0.8 ?A have been obtained with terminal voltage between 1.8 and 6 MV. The modified source has been used with K-vapor exchange for continuous periods of up to 120 hours without deterioration of source performance. Normal operation with H2 gas exchange for other beams is possible without the interruption of the source operation.     

A Nominal One-Megavolt, Pulsed Power Generator

A pulsed voltage generator, called Frizz, has been designed and constructed at Sandia Laboratories and is now being used as a voltage source for breakdown studies of various materials. Frizz generates a nominal 100 ns pulse of variable risetime from 5 to 50 ns across a vacuum chamber in which dielectric test samples are placed.     

A magnetically insulated negative ion source for neutral beam heating

A new, magnetically insulated negative ion source has recently been discovered which can produce pulsed negative ion beams (H^?, Li^?, and C^?) with intensities of of 100–300 A/cm² at 1–4 MeV. This source may provide the basis for a high energy neutral beam system for heating large tokamaks.     

Six stirrup handled Moche ceramic vessels from pre-Colombian Peru: a technical study applying PIXE spectrometry

Much has been said recently concerning the Moche culture of Peru (100 to 700 ) which preceded the more widely known Inca society. Since there was no written language, what is known about the Moche people has been through the artifacts produced, their design and craftsmanship. This study concerns the PIXE analysis of the matrix and the red and white surface patterns of six stirrup handled earthenware vessels. The results suggest different techniques were applied for producing the coloring and surface designs and that a common source of clays was not used in the construction.     

团簇尺度的瑞利散射测量中光电倍增管信号刻度与归一化处理

利用光电倍增管测量团簇的瑞利散射,信号幅度与团簇源背压有关,也与光源强度和光电倍增管工作电压有关.当团簇源背压变化范围较大时,散射信号幅度变化可能导致光电倍增管信号超出线性范围.为此,在不同的光源强度、不同的工作电压下对光电倍增管输出信号进行了刻度,得到了输出信号幅度随光源强度、工作电压之间的关系.用此关系.对不同条件下的实验数据进行归一化处理,得到了团簇散射因子随团簇源背压的关系曲线,与同类实验和理论结果相符.     

The use of an electrothermal plasma gun to simulate the extremely high heat flux conditions of a tokamak disruption

Disruption damage conditions for future large tokamaks like ITER are nearly impossible to simulate on current tokamaks. The electrothermal plasma source SIRENS has been designed, constructed, and operated to produce high density (> 10²⁵/m³), low temperature (1–3 eV) plasma formed by the ablation of the insulator with currents of up to 100 kA (100 s pulse length) and energies up to 15 kJ. The source heat fluence (variable from 0.2 to 7 MJ/m²) is adequate for simulation of the thermal quench phase of plasma disruption in future fusion tokamaks. Different materials have been exposed to the high heat flux in SIRENS, where comparative erosion behavior was obtained. Vapor shield phenomena has been characterized for different materials, and the energy transmission factor through the shielding layer is obtained. The device is also equipped with a magnet capable of producing a parallel magnetic field (up to 16 T) over a 8 msec pulse length. The magnetic field is produced to decrease the turbulent energy transport through the vapor shield, which provides further reduction of surface erosion (magnetic vapor shield effect).     

高位置分辨平行板雪崩室的研制

描述了灵敏面积为 10 0 mm× 10 0 mm和 150 mm× 150 mm两维位置灵敏雪崩室。采用分块结构 ,电极从两端分前后点引出 ,增加了延迟线的长度 ,延迟线跨边连接和在大气中直接封真空技术。在流动的 4 2 0 Pa的正庚烷气体中 ,用2 52 Cf裂变源对探测器的性能进行了测试 ,得到Δx=Δy=1mm的位置分辨。     

Zener diodes for gamma-ray radiation dosimetry

The fundamental properties of Zener diodes and junction field-effect transistors have been studied to use them as a relative dose monitor or a radiation-damage monitor. The response observed at liquid nitrogen temperature, i.e., radiation-induced change in the breakdown voltage of the Zener diode, or change in the breakdown voltage of the pn junction between the gate and the channel (or between the substrate gate and the channel) of the junction field-effect transistor as a function of dose, has shown good linearity. The diode of Toshiba 05Z18 has been found to be useful for doses between 1 and 100 MGy with the fading of response less than 10% for 100 h after irradiation. On the other hand, the junction field-effect transistors of Mitsubishi 2SK33 has proved useful in the region between 0.1 and 10 MGy with the build-up of responses less than 5% for 100 h. The response of both the junction field-effect transistor and the Zener diode has shown a reproducibility within ±5%. For fast readout, a simple system consisting essentially of a constant-current source together with a digital voltmeter has been constructed. For practical application, the devices from which soldered leads are taken off can be used simply to measure relative doses in various materials     

Potential impacts to operating nuclear power plants due to application of revised source term

TID-14844 was promulgated in 1962, and more than 30 years later there has been a big change of the US NRC's regulatory position in using accident source term for radiological assessment following a design basis accident (DBA). To replace the instantaneous source term of TID-14844, the time-dependent source term of NUREG-1465 was introduced in 1995, which represents the accident source term enveloping all light water reactor plants. In the meantime, the radiological acceptance criteria for reactor site evaluation in 10 CFR Part 100 were also revised. In particular, the concept of a total effective dose equivalent (TEDE) has been incorporated in accordance with the radiation protection standards set forth in revised 10 CFR Part 20. Subsequently, the publication of Regulatory Guide 1.183 and the revision of the Standard Review Plan 15.0.1 followed in 2000, which provided the licensee of a operating nuclear power reactor with the acceptable guidance of applying the revised source term. The guidance allowed the holder of an operating license issued prior to 10 January 1997 to voluntarily revise the accident source term used in the radiological consequence analyses of DBA. Depending on its type of application, there were suggested full and selective applications. Whether it is full or selective, based upon the scope and nature of associated plant modifications being proposed, the actual application of the revised source term to an operating plant is expected to give a large impact on its facility design basis. Prior to its actual implementation of design modifications, it is necessary to identify and analyze the potential impacts of each type of application and to derive the considerations taken in each application. In this paper, the experiences and lessons learned from its application to Ulchin Unit 3&4 are evaluated and presented.