MgO薄膜二次电子发射系数测量装置的设计

Mg O薄膜的二次电子发射系数 γ在彩色等离子体显示器的研究中是一个非常重要的参数。因此 ,准确的测量 Mg O膜的二次电子发射系数是很有必要的。本文分析了在二次电子发射系数测量中最容易出现的一些问题 ,并从 Mg O膜的二次电子发射机理入手 ,阐述了一种测量二次电子发射系数的方法。这种方法在实践中证明是行之有效的。     

真空器件中电极表面微结构对其二次电子发射性能的影响

本文在概述金属材料二次电子发射性能和用于行波管多级降压收集极的低二次电子发射系数电极材料研究的基础上,对电极材料表面尖锥阵列微结构层对二次电子发射性能的影响进行了有限元计算分析,进而提出了具有三维网络结构的电极表面微结构层概念,为构建新型超低二次电子发射系数电极材料提出了思路。     

一种航天器有效载荷新型高功率微波开关

为了抑制空间高功率器件中微放电击穿,本文提出了一种表面多孔结构。通过在器件表面构造该多孔结构,实现对二次发射电子的禁锢,从而减小器件表面二次电子发射系数,提高微放电阈值。通过模拟分析不同金属材料表面的二次电子发射特性,结合波方程和电子动力学理论建立电磁粒子模拟算法,实现不同微观表面微波器件的数值模拟。使用偏置电流法测量不同条件下金属的二次电子发射数据。模拟计算一定功率电平下典型微波开关微放电的物理图像。测量给出不同银表面处理下的二次电子发射特性,并且模拟给出微放电阈值。模拟结果与实验结果吻合良好,证明了表面多孔结构对微放电的有效抑制。     

二次电子发射系数对新型SM􀀁PDP 放电过程的影响

针对新型荫罩式PDP(SM-PDP)结构，采用二维数值模拟的方法研究了二次电子发射系数对放电过程的影响；以及在放电单元不同的表面上，二次电子发射系数对放电过程影响。通过计算比较得知二次电子发射系数越大，响应频率越快，粒子电离率越高；在SMPDP中，二次电子发射主要是由粒子轰击放电单元内上下介质表面决定的。     

二次电子发射系数的测量及应用

对多种材料的二次电子发射系数进行了测量,并讨论了这些受试材料的二次电子发射特性和发光效率。通过测量,可选择合适的材料以改善ＰＤＰ的性能。     

金刚石二次电子发射特性的研究

对高导热人造多晶金刚石、电镀人造金刚石及天然金刚石的二次电子发射特性进行了研究。测得金刚石的二次电子发射系数小于铜及镍,与热解石墨相当或更低。     

真空电子技术

O462.2200801273绝缘体二次电子发射系数测量装置的研制/谢爱根,郭胜利,李传起,裴元吉(南京信息工程大学物理系)//强激光与粒子束.―2007,19(1).―134～138.成功研制了测量绝缘体二次电子发射系数的测量装置,该装置主要由栅控电子枪系统、真空系统和电子采集系统组成,测量装置产生的原电子流的能量范围为0.8～60keV。采用单脉冲电子枪法,测量了原电子能量范围为0.8～45keV的多晶MgO的二次电子发射系数。测量中,收集极(偏置盒)离材料表面设置为约35mm,偏置电压设置为45V。测量得到:用磁控溅射法制备的MgO的二次电子发射系数最大值约为2.8…     

抑制行波管多级降压收集极二次电子发射的工艺研究

利用自行设计制造的一台抑制行波管多级降压收集极（MDC）二次电子发射的专用设备,分别对无氧铜片样品与无氧铜MDC进行了离子束表面改性的工艺研究。结果表明,表面改性后无氧铜表面二次电子发射系数可以得到大幅度的降低,有效提高空间行波管MDC的效率及整管效率。     

PDP器件中MgO薄膜二次电子发射系数γ的研究

结合等离子体显示器件 ( PDP)的放电机理 ,论述了 PDP中 Mg O保护膜的二次电子发射过程 :势能型发射和动能型发射。讨论了两种二次电子发射系数 γ的测量方法和装置 ,在此基础上 ,建立了一套简单可行的适用于 PDP样品的实验装置 ,文中给出γ值的测量结果。通过γ值的测试 ,可以反馈 Mg O保护膜的性能 ,为提高PDP性能提供依据     

纳米MgO晶体制备及其二次电子发射系数理论研究

为了研究MgO晶体和二次电子发射效率间的关系,分析了直接沉淀镁盐法生成Mg(OH)_2以及三段式温度煅烧Mg(OH)_2制备MgO晶体的过程,并使用扫描电镜和XRD对制成的MgO晶体进行了表征。在此基础上,采用第一性原理对MgO晶体的能带结构和态密度进行了计算,分析了晶体表面的结晶取向对MgO二次电子发射系数的影响。实验结果表明,本方法制备的MgO为立方晶体,且晶粒尺寸均匀分布在40.65nm附近,晶面取向为(200)、(111)、(220),并沿(200)取向择优生长。常见的(110)、(100)和(111)三种晶面取向中,表面(110)取向的MgO晶体禁带宽度最低,材料表面的二次电子发射系数相对较高。     

Photon-induced charge transfer and surface emission

Experimental measurements have been made of photon-induced charge transfer between plane-parallel electrodes. X-rays from a pulsed X-ray source were directed at near-normal incidence onto plane-parallel electrodes, and the current which flowed between the electrodes during the X-ray pulse was measured. Quantities obtained include bulk charge transfer in several dielectric materials; forward and reverse electron emission from Al, Cu, and Au surfaces; and secondary electron emission coefficients for these metals and selected dielectrics. Measured values for charge transfer and surface emission are compared with calculations.     

Secondary emission properties as a function of the electronincidence angle

Computer codes being developed to improve the understanding of crossed-field amplifier (CFA) performance require a more complete and reliable database of the secondary electron emission properties of the electrode materials than exists in the literature. The authors describe an experimental method and present results of secondary emission yield measurements on molybdenum surfaces, both clean and gas-exposed. The surface cleanliness was monitored by Auger electron spectroscopy (AES), and all measurements were made under ultrahigh-vacuum conditions (better than 1×10^-10 torr). The results differ from the existing data for which the surface cleanliness was not determined. The secondary electron emission yields were measured as a function of the primary electron energy and also of the angle of incidence. The results were fitted with the analytical expressions of J.R.M. Vaughan (1989), with good overall agreement if Vaughan's formulas are slightly modified     

The effects of titanium films on secondary electron emission phenomena in resonant cavities and at dielectric surfaces

The phenomenon of electron bombardment heating of insulators in vacuum under the influence of RF fields by several types of multipactor processes is reviewed. Evidence is given to show that a practical way of limiting the electron bombardment of insulators is to provide surfaces which have a maximum secondary electron emission yield of less than one on both the insulator and on the related metal surfaces. Thin films of titanium metal are shown to have a very good effect on suppressing the secondary electron multiplication processes at both the metal and dielectric. The discontinuous nature of very thin metal films makes it possible to coat dielectrics with titanium with thicknesses sufficient to reduce the secondary emission yield without adding significantly to the loss factor or to the dc conductivity.     

用离子束技术改善材料电子发射特性的研究

本文用离子束技术，使铜网的二次电子发射系数降低，场发射性能得到改善，钼网的“栅发射”得到抑制，测量并讨论了逸出功变化对电子发射性能的影响，研究表明，离子束技术是改善材料电子发射性能的有效手段。     

测量热阴极次级发射特性的扫描电子探针法

本文介绍了一种适用于量测热阴极次级发射特性的扫描电子探针法,原电子探束束斑直径为50100m,束流小于10-7A,原电子能量不大于3kV。该装置能定点测量热阴极表面上感兴趣点的次级发射系数与原电子能量间的关系曲线(-Ep);也能以扫描方式在短时间内测出整个热阴极表面的次级发射分布,从而求得次级发射的定量分布曲线(f-)。该装置在电视制式的扫描方式工作时,能观察热阴极表面的次级发射图象。 对纯镍样品的测量表明:该装置具有比单枪定点法更多的优点和更高的精度。由于该装置简便灵活,便于与热阴极研究的特殊需要相结合,因此,可望在热阴极的研究中发挥作用。     

浸渍镱酸盐阴极

本文介绍了一种新型钡钨阴极镱酸盐阴极,这种阴极是以多孔钨海绵为基体,浸渍镱酸盐发射材料而制成。该阴极具有大的次级电子发射系数,在室温下,为4.1;较大的热发射,在1000℃,可支取6A/cm2的电流密度,而且阴极表面发射比较均匀;有较强的抗氧中毒能力;是一种较好的实用阴极。     

A NEW Ba-W DISPENSER CATHODE IMPREGNATED WITH BARIUM YTTERBATE

A new kind of Ba-W dispenser cathode impregnated with barium ytterbate has been deve-loped.It has good properties;high coefficient of secondary emission,strong ability of resisting oxygenpoisoning,high thermionic emission current density and more uniform emission on the cathode surface.The cathode is suitable for using as an electron emitter for microwave tubes,especially magnetrons.     

Effect of random secondary delay times and emission velocities inelectron multipactors

Traditionally, the modeling of rf driven electron cascades (multipactors) has employed a constant emission velocity and zero delay time for all secondaries. This paper introduces the effects from the random secondary emission velocities, as well as the random delay time in the secondary emission. By combining the emission related random phase kicks with the focusing rf action it is shown that the electron impact phase, though wandering erratically, nevertheless stays in the vicinity of a stable phase-locked multipactor phase; the rms phase deviation from phase locking is bounded and directly proportional to the rms fluctuation in the secondary emission. The random phase wandering around the locked phase reduces the nominal secondary emission coefficient δ to an effective value δ* between δ>δ*⩾δ/2 and depending not only on the impact energy of the primary but also on the thermal spread of the secondaries. Multipactor quenching from secondary spreads may occur through the reduction in δ*. For sufficiently small fluctuations, the modeling of a “cold” multipactor with zero thermal spreads is sufficient to determine the actual multipactor behavior in terms of only two control parameters; the normalized rf and magnetic field strengths     

脉冲磁控管的阴极问题

在脉冲磁控管中,阳极电流可以用两个不同的公式表示。一是属于具体管型的,包含电磁参数和管的几何尺寸,它描述阳极如何从切向迴旋的电子云中提取电子。另一个只与阴极的热发射、回轰系数和次级发射系数有关,它描述阴极向迴旋电子云供应电子的一般方式。二者有紧密的联系,但又是不同的物理过程。我们将这两个公式和互作用空间中的电子云运动结合起来,便能更好地了解磁控管的工作机制。 为了使磁控管能稳定工作,就要使预振电压低于门槛电压,并且使空间电荷振荡的模式与谐振腔上高频振荡的模同步。在起振之后,阳极电流应近似地由次级发射供应,而回轰电流则近似地由热发射供应。此条件能保证得到较好的工作状态。