Ir—Ce合金阴极及其应用研究

重点研究了粉末冶金法制备Ｉｒ－Ｃｅ（铱－铈）合金阴极过程中压制压力和烧结温度对发射性能的影响，建立起了一套稳定的制备工艺。试验得到Ｉｒ－Ｃｅ掺Ｗ阴极在１７５３Ｋ时的发射电流密度达１２．４Ａ／ｃｍ２，电流密度保持为１．７Ａ／ｃｍ２，发射试验稳定达１５０ｈ。从机理上验证了它是一种高温大发射电流的发射体。试验还表明Ｉｒ－Ｃｅ阴极具有良好的抗中毒能力。作为应用研究，测量了该阴极在热阴极微波电子枪中的发射性能，微波腔场强约１０ＭＶ／ｍ，工作温度１９１３Ｋ，零场发射电流密度为１０Ａ／ｃｍ２，最大发射电流密度达２１Ａ／ｃｍ２，在２０２０Ｋ时计算零场发射电流密度可达４２Ａ／ｃｍ２。     

大发射电流密度Ir－Ce合金阴极的研究

制作了一种发射电流密度较大的铱－铈两相合金阴极。在１７７３Ｋ时，阴极零场发射电流密度为６７５Ａ／ｃｍ２，有效逸出功为２．７３ｅＶ；在１８２３Ｋ时，观察到最大发射电流密度超过２１．２Ａ／ｃｍ２。同时简介了阴极制作工艺和抗中毒情况以及未来的改进发展方向。     

大发射电流密度Ir—Ce合金阴极的研究

制作了一种发民流密度较大的铱－铈两相合金阴极。在１７７３Ｋ时，阴极零场发射电流密度为６．７５Ａ／ｃｍ＾２，有效逸出功为２．７３ｅＶ；在１８２３Ｋ时，观察到最大发射电流密度超过２１．２Ａ／ｃｍ＾２。同时简介了阴极制作工艺和抗中毒情况以及未来的改进发展方向。     

阴极条室性能研究的结果

本文介绍了６０ｃｍ×５０ｃｍ阴极条室的设计，研制和性能研究的结果。实验测量得到的空间分辨σ≌５０μｍ，实验证明了阴极条室具有良好的性能，使其有着很好的应用前景。     

MEVVA型金属离子源

本文报道金属蒸发真空孤放电（ＭＥＶＶＡ）型金属离子源的研究结果。阴极材料分别使用了Ａｌ、Ｔｉ、Ｆｅ和Ｃｕ。阴极触发脉冲１２ｋＶ，脉冲宽度９０μｓ，脉冲重复率１－５次／ｓ。引出束流脉冲宽度３００μｓ。当引出电压为２８ｋＶ时，可引出Ａｌ、Ｔｉ、Ｆｅ和Ｃｕ离子流强度分别为２３０ｍＡ、２５０ｍＡ、２８０ｍＡ和３００ｍＡ     

新的心血池显像剂^99Tc^m—DTPA—HSA的实验研究

＾９９Ｔｃ＾ｍ－ＤＴＰＡ－ＨＳＡ心血池显像剂于２０只家兔进行实验研究，并与＾９９Ｔｃ＾ｍ－ＲＢＣ（体内法）及＾９９Ｔｃ＾ｍ－ＨＳＡ进行比较。由＾９９Ｔｃ＾ｍ＝ＤＴＰＡ－ＨＳＡ所得心血池显像的图像清晰。生物学分布研究表明，＾９９Ｔｃ＾ｍ－ＤＴＰＡ－ＨＳＡ在肝和肺的浓聚较＾９９Ｔｃ＾ｍ－ＲＢＣ及＾９９Ｔｃ＾ｍ－ＨＳＡ略低。心／肝放射性比值，＾９９Ｔｃ＾ｍ－ＤＴＰＡ－ＨＳＡ为０．８５，＾９９Ｔｃ＾ｍ－Ｒ     

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。     

LaMo阴极材料的制备与对比测试

对ＬａＭｏ阴极材料的制备进行了探索性的尝试，并对从美国购进的ＬａＭｏ阴极材料和自制的ＬａＭｏ材料的发射特性及用于强流离子源的弧放电性能进行了对是度是了较好的实验结果。     

JT—60U长脉冲,高βN放电中磁岛宽度的测量

通过用一个外差辐射计测量电子回旋发射的振荡，估算了长脉冲、高βＮ放电期间的磁岛宽度。由于外差计的高空间分辨率约为２ｃｍ，所以能详细地测量磁岛结构的演变。磁岛宽度随着起伏的幅度而增大。当ｍ／ｎ＝３／２模出现时，饱和的磁岛宽率约为７ｃｍ。限制可持续的βＮ的电阻模的模数一般为ｍ／ｎ＝３／２和２／１。本文讨论了预测到的磁岛与新经典撕裂模之间的关系。     

10cm×10cmCSC模型室的测试系统软件

阴极条读出探测器（ＣＳＣ）具有特点使其成为美国ＳＳＣ实验室ＧＥＭ合作中μ探测器的被选对象。本文介绍高能物理所研制的ＣＳＣ１０ｃｍ×１０ｃｍ模型的性能测量所应用的软件。     

Plasma characteristics in the discharge region of a 20A emission current hollow cathode

Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter.The results of the two methods indicated that the highest plasma density and electron temperature,which improved significantly in the orifice region,were located in the discharge region of the hollow cathode.The magnitude of plasma density was about 10~(21)m~(-3)in the emitter and orifice regions,as obtained by numerical calculations,but decreased exponentially in the plume region with the distance from the orifice exit.Meanwhile,compared to the emitter region,the electron temperature and current improved by about 36%in the orifice region.The hollow cathode performance test results were in good agreement with the numerical calculation results,which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current.The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.     

An experimental study on the degradation of the C12A7 hollow cathode

Emitter overheating is by far the greatest problem limiting the performance of novel C12A7 hollow cathodes. To explore the failure operating point and degradation mechanism of the C12A7 hollow cathode, microscopic analyses of a degraded electride emitter after 10 h of thermal electron emission are presented in this paper. The morphology and composition variation of overheated electride emitters by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction indicate the melting and decomposition of electride of the surface layer. The monitored temperature of the electride emitter during the C12A7 hollow cathode operation shows that to avoid overheating the electride emitter, the average current density allowed should be about 64 mA mm−2 for the C12A7 hollow cathode in its current configuration. Experimental results of the heaterless C12A7 hollow cathode demonstrate that xenon (Xe) ion bombardment can remove the insulating layer and restore the thermionic emission capability for less degraded emitters. Based on experimental results and microscopic characterization, the depletion and degradation mechanisms of electride emitters during the hollow cathode operation are discussed.     

Oxide Coated Cathode Plasma Source of Linear Magnetized Plasma Device

Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm 2 to 6 A/cm ² in pulsed mode within pulse length 5–20 ms. A 10 cm diameter, 2 m long plasma column with density 10 ¹⁸ m ⁻³ to 10 ¹⁹ m ³ and electron temperature T_e ≈ 3–7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.     

六硼化镧阴极在双等离子体离子源中的应用

一、引言早在50年代初,J.M.Lafferty就研究了六硼化镧阴极的电子发射特性。70年代中期以后,六硼化镧阴极广泛地应用于现代技术的许多领域。例如,等离子体发生器、强流离子源(包括用于聚变研究中的中性束注入源)、电子显微镜、质谱仪和一些电子器件(真空规管,热电离变换器等)。     

Influence of heating on the discharge characteristics of a hollow cathode

Hollow cathodes are widely used as electron sources and neutralizers in ion and Hall electric propulsion. Special applications such as commercial aerospace and gravitational wave detection require hollow cathodes with a very wide discharge current range. In this paper, a heater is used to compensate for the temperature drop of the emitter at low current. The self-sustained current can be extended from 0.6 to 0.1 A with a small discharge oscillation and ion energy when the flow rate is constant. This is also beneficial for long-life operation. However, when the discharge current is high(1 A), heating can cause discharge oscillation, discharge voltage and ion energy to increase. Further, combined with a rapid decline of pressure inside the cathode and an increase in the temperature in the cathode orifice plate, electron emission in the orifice and outside the orifice increases and the plasma density in the orifice decreases. This leads to a change in the cathode discharge mode.     

碳团簇及C60负离子的产生

利有铯负离子溅射源和石墨阴极产生并引出了碳团簇负离子流，观察到了一些电子亲和势很小的团簇，用Ｃ６０／Ｃ７０混合物做阴极，也引出了Ｃ６０及其碎片的负离子束，分析了碳团簇负离子束流的质谱组成特点和束流变化的一些规律。     

Characteristics of a High Current P.I.G. Ion Source at Low Gas Pressure

The characteristics of a 10 cm P.I.G. (Penning ionization gauge) discharge and its application as an ion source at a low pressure are given. Using a hot cathode two regions of operation are found, one above and the other below 1 micron. Pulsed ion current reaching 1 Ampere could be extracted from this source through a 10 cm diameter gridded cathode at a discharge current of about 20 Amperesand a gas pressure of 0.5 micron. The cathode discharge current was found to contain electrons. The ion current to the reflector cathode is about 10% of the discharge current.     

在线低能气体离子源

材料中氦和氢积累可引起材料性能的恶化甚至失效。为研究材料内氦和氢的存在形式、氦与氢及缺陷的相互作用、气泡的形成和演变过程以及各种因素的影响,建立一套离子束能量最高20keV的潘宁型气体离子源引出和聚焦系统,与200kV透射电镜联机,在离子注入现场原位观察氦和氢不同注入浓度下材料内部的微观结构及变化过程。对离子源进行氦离子的起弧、引出和聚焦测试。离子源在15–60mA放电电流范围内稳定地工作。在5×10–3Pa和1.5×10–2Pa工作气压下,放电电压约380V和320V。低气压下引出离子束流比高气压下大,且引出束流随放电电流和吸极电压的增加而增加。等径三圆筒透镜有显著聚焦作用,在距透镜出口150cm处,离子束流密度提高一个量级以上。能量10keV左右的氦离子获得束流密度约200nA·cm–2的离子束,可满足多种材料进行在线离子注入和原位电镜观测的需要。