Beam optics optimization of a negative-ion sputter source

A negative-ion sputter source has been studied in order to increase the beam intensity delivered by the Vivitron tandem injector. The aim was to characterize the influence on the beam intensity of some factors related to the configuration of the source such as the shape of the target holder, the target surface topography and the anode/cathode voltage. The paper reports the results carried out by experimentation on a test facility and on the injector itself as well as the investigations performed with computer simulations.     

Plasma characterization on carbon fiber cathode by spectroscopic diagnostics

This paper mainly investigates plasma characterization on carbon fiber cathodes with and without cesium iodide (CsI) coating powered by a ～300~ns, ～ 200~kV accelerating pulse. It was found that the CsI layers can not only improve the diode voltage, but also maintain a stable perveance. This indicates a slowly changed diode gap or a low cathode plasma expansion velocity. By spectroscopic diagnostics, in the vicinity of the cathode surface the average plasma density and temperature were found to be ～ 3× 10¹⁴~cm^-3 and ～ 5~eV, respectively, for an electron current density of ～ 40~A/cm². Furthermore, there exists a multicomponent plasma expansion toward the anode. The plasma expansion velocity, corresponding to the carbon and hydrogen ions, is estimated to be ～ 1.5~cm/μ s. Most notably, Cs spectroscopic line was obtained only at the distance ≤ 0.5~mm from the cathode surface. Carbon and hydrogen ions are obtained up to the distance of 2.5~mm from the cathode surface. Cs ions almost remain at the vicinity of the cathode surface. These results show that the addition of CsI enables a slow cathode plasma expansion toward the anode, providing a positive prospect for developing long-pulse electron beam sources.     

A reliable noble gas duoplasmatron for the 10 mA range

Duoplasmatrons have been employed at GSI as accelerator sources of multiply charged heavy ions, but extensive experience was collected also with singly charged noble gas ions. Other ion species can be produced from volatile compounds. provided that the cathode is protected from aggressive vapours by an additional noble gas. In a second source modification. the sputter duoplasmatron, ions are directly obtained from solid material.

Recently the GSI-duoplasmatron has been equipped with plasma expansion cups in order to raise the ion current output. Generally, at least a factor of three is gained in beam intensity and other aspects of source performance are improved, too.

A new cathode design considerably enhances life-time and reliability, permitting uninterrupted operation for a few hundred hours. Tables of measured ion beam currents are given.     

吉瓦级强流相对论多注电子束二极管的优化设计与实验研究

多注相对论速调管放大器可在较高的工作频段实现GW级功率微波产生,在很多领域得到了发展和应用.多注相对论速调管中强流相对论多注电子束相互之间存在空间电磁场的作用,使得多注电子束从二极管引入多注漂移管,以及在多注漂移管中的传输运动受到影响,导致电子束会轰击到管壁上,早期实验中多注电子束的传输通过率较低.本文对功率数GW的强...     

多靶强流铯溅射离子源的研制

多靶强流铯溅射离子源是多种加速器中常用的离子源之一,在科学研究和工业生产领域的应用十分广泛。但是,目前商业化应用的该种离子源由欧美几个国家垄断,国内还没有厂家能够生产。为了提高加速器运行和建造中的自主化水平,研制了一种多靶强流铯溅射离子源。该离子源主要由离子源腔、换靶装置、冷却系统、控制箱等组成,根据功能需求对其关键部件进行结构设计,采用了全新的伺服电机驱动换靶方式,提供靶位微调功能和远程控制模式,并使用Opera-3D软件模拟优化结构参数和束流光路。经过测试,该离子源在中国原子能科学研究院的400 kV小型加速器质谱(AMS)装置上应用情况良好,换靶定位精准,供束稳定,束流参数达到进口离子源的参数指标,实现了预期目标。     

采用组合引导磁场的多注二极管设计

分析了采用单一同轴磁场时强流相对论多注阴极的侧端发射问题,研究了在不同磁场内半径和多注漂移管长度情况下多注电子束的传输效率。研究发现:由于引导磁场尺寸有限,高压下多注阴极杆及多注阴极柱的电子束发射是影响多注电子束传输效率的主要因素,且该部分电子束对多注漂移管入口管壁的轰击直接影响了多注速调管的重频能力。设计了采用永磁铁和同轴磁场组合工作的强流相对论多注二极管,理论分析和模拟计算证明:基于组合磁场的多注二极管可明显减弱甚至抑制多注阴极发射球头以外的电子束发射,并且组合磁场的磁场位形和强度可满足强流相对论多注电子束的高效、稳定传输。     

Design of a re-entrant double-staggered ladder circuit for V-band coupled-cavity traveling-wave tubes

The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling-wave tube is constructed. The electromagnetic characteristics and the beam-wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.     

基于滤光片提取光谱的流动注射-溶液阴极辉光放电检测研究

溶液阴极辉光放电-原子发射光谱法是近年来兴起的一种新型水体金属离子检测技术,它具有快速,在线和低成本检测的显著特点。以工业注射泵实现溶液阴极辉光放电激发源的流动注射进样,再以窄带滤光片分别提取Na,K,Ca,Li,Sr和Cs金属元素发射光谱信号,最后由光电倍增管和皮安表接收光谱信息光谱信号,实现了水质金属元素的检测。实验分析了注射容量分别为100和166 μL对1 mg·L-1的Na元素产生的信号强度的影响,研究发现其信号强度的相对标准偏差（RSD）分别为4.64%和1.95%,说明两种注射量稳定性都较好。为了获得更好的分析性能,实验分析了直流放电电压,狭缝的宽度以及光电倍增管供压等参数对信号强度的影响。实验结果表明,在直流放电电压为1 000 V,狭缝宽度为70 μm和光电倍增管供压为-800 V时获得了较高的信背比。采用此装置在流动注射模式下,测得了Na,K,Ca,Li,Sr和Cs六种金属元素检出限,分别为2.78,4.23,589,9.45,981和83.6 μg·L-1。实验最后对混合溶液标定物质中的Na和K元素进行了定量分析测量,测量的误差分别为7.5%和6.67%,精密度分别为1.24%和0.89%,研究结果表明基于滤光片提取光谱的流动注射分析-溶液阴极辉光放电-原子发射光谱方法具有较高的检测准确度。     

磁绝缘线振荡器阴极烧蚀与电压波形的关系研究

通过粒子模拟和实验研究相结合的方法,研究了磁绝缘线振荡器的阴极烧蚀与输入电压波形的关系,找到了造成阴极烧蚀的根本原因,给出了电子束回轰阴极的清晰图像,并通过对低阻抗加速器平台输出电压波形的调整,抑制了反向电压,解决了器件的阴极烧蚀问题.研究结果表明:在正向电压作用下已经发射出来的电子束在超过一定幅度的反向电压作用下发生反向运动并回轰阴极,产生反向电流并造成器件阴极的烧蚀,因此注入电压下降沿之后的反向电压是引起磁绝缘线振荡器的阴极烧蚀的最根本因素.     

猝发强流多脉冲电子束源物理设计

给出一台脉冲间隔100～1 000 ns、脉冲数2~5个、二极管电压3 MV、引出束流强度2.5 kA的猝发多脉冲电子束源的物理设计及初步调试结果。在设计中,采用感应叠加和阻抗匹配方案获得二极管高电压脉冲;试验中分别采用天鹅绒和大发射面储备式热阴极获得猝发多脉冲电子束。调试结果表明:采用大发射面热阴极可避免阴极等离子体产生,确保二极管在猝发多脉冲状态下稳定运行。初步调试获得大于2.7 MV猝发三脉冲二极管高压,并获得1.6 kA的三脉冲电子束流。     

双阶梯阴极型磁绝缘线振荡器设计与模拟

 结合负载限制型磁绝缘线振荡器（MILO）和渐变型MILO的特点,提出了一种新型双阶梯阴极型MILO。该器件前2个叶片为扼流片，中间3个叶片为主作用叶片,后面1个为提取叶片，在电流发射区与慢波结构径向相对的阴极部分分为3段，形成双阶梯阴极结构。根据Maxwell方程和Floquet定理导出其色散方程，并对其振荡主频作了理论分析。2.5维粒子模拟表明，器件工作频率为1.21 GHz，与理论预测相符，双阶梯的引入，对器件阻抗和振荡频率影响较小。在工作电压458 kV、电流40.5 kA条件下，双阶梯阴极结构将MILO输出功率从2.20 GW提高到2.88 GW，功率转换效率从12.0%提高到15.5%。     

强流碳纳米管阴极快脉冲重频发射特性

在Cu基底上, 采用催化热解生长法制备了石墨化程度较高的碳纳米管阴极. 当电子束能量达到1 MeV、梯度约为60 kV/ns时, 发射束流强度达到15 kA, 相应密度约为1 kA/cm², 束压、束流响应快, 波形间几无延时. 以50 Hz重复频率、约15 GW束功率强流发射时, 波形稳定, 随着频率增高, 稳定性降低. 发射炮次达1000后, 表面形貌保持完整、界面无脱附; 束压与束流基本满足空间电荷限制定律, 发射机理属闪络型等离子体发射, 等离子体速度约为3.9 cm/μs.     

碳酸铯修饰Al作为反射阴极的倒置顶发射OLED器件

以Cs₂CO₃修饰的Al电极作为反射阴极制备了高效倒置顶发射结构有机电致发光器件(ITOLED)。以八羟基喹啉铝(Alq₃)作为发光层、MoO₃修饰的Ag为半透明阳极时,器件的开启电压为3.6 V,发光效率和功率效率分别达到9.8 cd/A和3.4 lm/W。研究结果表明,Al/Cs₂CO₃为反射阴极的器件性能明显高于使用Mg:Ag(4.2 V,8.6 cd/A,2.85 lm/W)和Al(5 V,5.5 cd/A,1.57 lm/W)作为反射阴极的倒置顶发射OLED器件。单电子器件研究结果证明,以Cs₂CO₃修饰的Al电极功函数明显低于Mg:Ag和Al电极,具有更好的电子注入效果。因此,除去微腔效应外,Al/Cs₂CO₃为反射电极的ITOLED器件性能的提高主要归因于Al/Cs₂CO₃阴极的有效电子注入。     

Wide-aperture high-current electron beam in a discharge with cathode plasma at elevated pressure

This work pursues investigations into the discharge with a cathode plasma in a cavity one wall of which is an insulating plate with a hole D in diameter (the cavity is 0.5 or 1.5 mm wide). This discharge is thoroughly analyzed in comparison with the high-voltage hollow-cathode discharge. Owing to the reduced emission of electrons from the cathode plasma, the discharge becomes more stable against transition to the low-voltage form, as a result of which an electron beam can be generated under higher gas pressures. Such a beam formed at the entrance to the cavity is used as an auxiliary one that propagates over the remaining (flat) surface of the cathode and adds to the gas ionization. Accordingly, the beam current from the main discharge to the anode rises (high-current regime). Wide-aperture (D = 22 mm) ≈1-μs-long pulsed beams with a current an order of magnitude higher than the total current of the equivalent anomalous discharge are obtained. Experiments are carried out at a helium pressure to 20 Torr and a voltage from 1 to 20 kV.     

双离子束溅射沉积薄膜的光学特性与激光损伤研究

对氧化物薄膜的双离子束溅射沉积作用了系统地实验研究。考察了离子束溅射工艺参数对薄膜光学特性的影响。制备了折射率接近于块材料的ＴｉＯ２和ＺｒＯ２薄膜，显著降低了ＴｉＯ２，ＺｒＯ２和ＳｉＯ２薄膜的光吸收损耗，ＴｉＯ２和ＺｒＯ２薄膜的抗激光损伤阈值得到显著提高。用双离束溅射沉积１．０６μｍ多层高反，是到了大于９９．５％的高反射率，经高温退火处理的双离子束溅射沉积高反膜的抗激光损伤阈值同热蒸发沉积的高反膜     

Measurements of velocity ratio in a 90 MW gyroklystron electronbeam

Measurements of the ratio of perpendicular to parallel velocity (α=υ_⊥/υ,) in a 390-420 kV, 160-240 A, small orbit gyroklystron electron beam produced by a magnetron injection gun have been performed using a capacitive probe. The probe employed guard rings to reduce uncertainties in measurement and calibration due to fringing electric fields. These studies represent the first measurements of a in such a powerful rotating beam. Since the current levels in this experiment are two to three times higher than those in previous velocity ratio studies of beams with similar voltage. The effects of changes in voltage, current, and magnetic compression on the measured velocity ratio are investigated. Values of α in the range of 0.8-1.3 are typically observed, which are considerably higher than the values predicted by theoretical simulations. Errors in the modeling of space charge effects are ruled out as the cause of the discrepancy by the agreement between theoretical and experimental space charge current limits. Instead, a significant portion of the discrepancy is attributed to a reduction in cathode magnetic field by the self-axial magnetic fields of the electron beam     

Design of a reentrant double staggered ladder circuit for V-band coupled-cavity traveling-wave tube

The reentrant double staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, besides the easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling-wave tube is constructed. The electromagnetic characteristics and the beam--wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.     

The Experimental Study of Novel Pseudospark Hollow Cathode Plasma Electron Gun

The high-power microwave devices with plasma-filled have unique properties. One of the major problems associated with plasma-filled microwave sources is that ions from the plasma drift toward the gun regions of the tube. This bombardment is particularly dangerous for the gun, where high-energy ion impacts can damage the cathode surface and degrade its electron emission capabilities. One of the techniques investigated to mitigate this issue is to replace the material cathode with plasma cathode. Now, we study the novel electron gun (E-gun) that can be suitable for high power microwave device applications, adopting two forms of discharge channel, 1: a single hole channel, the structure can produce a solid electron beam; 2: porous holes channel, the structure can generate multiple electronic injection which is similar to the annular electron beam.     

On the radial distribution of the HeII 468.6 nm line intensity in a high voltage hollow cathode discharge tube

The radial distribution and spatial profiles of the HeII 468.6 nm line intensity in an internal anode type of the high voltage hollow cathode discharge (HV-HCD) tube have been investigated by a photographic technique using a narrow-bandpass interference filter. From the photographic data, it is inferred that the density of fast electrons near the tube axis of this HV-HCD tube is considerably higher than that of the conventional cylindrical type HCD tube.     

Electron beam formation in an anomalous glow discharge

Scaling parameters that account for the efficient formation of electron beams in sources based on an anomalous glow discharge are considered, and the processes leading to the violation of scaling laws are analyzed. Estimates show that the working pressure range in such sources can be increased significantly. The results obtained can be used to optimize discharge regimes with required electron beam parameters. It is demonstrated that sources with plane-parallel continuous electrodes can operate at pressures as high as 100 Torr (which is one to two orders of magnitude higher than that in similar existing electron beam sources), provided that parasitic spark breakdowns at the insulator near the discharge cathode are suppressed. The sources designed can be used for direct excitation of laser working media or their preionization by soft X-rays.