电荷交换离子对栅极系统束流影响的数值研究

采用二维网格质点法(PIC)计算离子在离子发动机栅极系统中的运动, 通过在模型中添加离子和中性粒子电荷交换的Monte Carlo碰撞模块, 得到了电荷交换离子在栅极周围的分布及电荷交换离子的运动规律.计算结果表明:考虑电荷交换离子后, 屏栅极电流较不考虑电荷交换离子情况时增大了1.42%, 所受影响不大, 加速栅极电流由0增大到主束流电流的1.41%.模拟结果表明:加速栅极下游较远处产生的电荷交换离子, 是造成加速栅极下游面腐蚀及加速栅极电流的主要原因.      

电子回旋共振离子推力器放电室低信号调试

微波输入技术是电子回旋共振离子推力器的关键技术之一,输入微波在推力器放电室内产生谐振的时候,微波功率才能高效地被吸收,从而电离气体,提高电子的能量,增加等离子体的电离度。电子回旋共振离子推力器放电室是一个不规则的微波谐振腔,很难从理论上确定其谐振状态下的结构。本文利用网络分析仪,采用微波无源器件回波损耗的测试方法对放电室进行精确调谐,分析微波谐振频率及带宽,目的在于详细研究放电室的结构尺寸、微波耦合探针形状和尺寸在谐振状态下的匹配性。调试结果表明放电室增加14 mm圆柱段,选择圆柱段长度22 mm和球形直径9 mm的组合探针,可以得到较好的谐振状态,此时腔体的回波损耗为-23 dB,谐振频率4.195 GHz,谐振带宽为0.025 0 GHz,品质因素为167.848。     

日光/H2O2/草酸铁催化氧化降解活性艳红的研究

研究了日光／H2O2／草酸铁体系以日光为驱动力对可溶性染料活性艳红进行降解反应．探讨了溶液的pH、H2O2、光强和活性艳红的起始浓度对催化反应的影响。结果表明。对活性艳红的降解速率受pH、H2O2、草酸铁的浓度、入射光强的影响很大。在研究范围内。pH=3．0和在17光照射下其降解效果最好,同时．表明在同一光强光源条件下色度、TOC的去除率均比在UV／TiO2的效果好。     

射频离子推力器研究进展

射频离子推力器由于高比冲、长寿命、高效率等优点在电推进领域中占有重要地位.为了进一步缩减推进系统的质量和体积,降低成本,一些新型射频离子推力器相继出现,其中无中和器射频离子推力器备受关注.对传统射频离子推力器的国内外研究及发展现状进行了总结,分析了射频离子推进技术中涉及的关键技术,概述了无中和器射频离子推力器的原理及研...     

高温合金材料螺孔加工技术研究

高温合金GH4169属镍基高温合金,是航天发动机高温系统中应用广泛的高温结构材料,但它的切削加工性能极差.如以相对正火状态45钢的切削加工性Kv=1来衡量,高温合金的切削加工性Ky=0.2～0.5,而镍基高温合金的Kv=0.2.其切削加工特点主要表现为强度高,塑性大,切削抗力大,冷作硬化严重,切削温度高,刀具在加工过程中磨损剧烈,以攻丝为加工最难点,小直径的螺孔用普通攻丝方法几乎无法加工,已经严重影响了公司的生产进度和产品质量.我们经过自己研究、攻关和与国内几所大学联合开发,特别是利用北京师范大学的离子注入技术,开发出加工高温合金螺孔的新型丝锥,现已用于公司的发动机生产,基本能满足公司的需要,解决了存在多年的高温合金的螺孔加工的难题.     

四氯化碳对1J116材料的腐蚀行为及机理探讨

以发生锈蚀的1J116材料产品为分析对象,应用能谱分析、模拟试验等方法,研究了锈蚀产生的原因、腐蚀介质的作用模式和腐蚀机理。实验表明,锈蚀形式主要表现为缝隙腐蚀,氯离子是引起锈蚀的重要条件,而产品清洗后系统中残留的四氯化碳、水和乙醇的混合溶液是氯离子的主要来源。     

基于SP+模型的航空锂离子电池组优化技术研究

随着多电飞机技术与锂离子电池技术的发展,锂离子电池已经广泛应用于航空领域,除作为应急电池外,越来越多地作为动力电池应用于飞机。因飞机对锂离子电池组质量、体积等特性具有很高的要求,需要对其进行优化设计,而采用基于模型的方法开展优化设计可以有效减少成本并缩短周期。由于SP+电化学模型能够准确反映锂离子电池的工作机理,同时具有精度高、计算简便等特点,因此文中采用SP+模型构建锂离子电池组模型并进行了验证。同时,以典型的用电工况为例,开展了航空锂电池组的优化设计,实现了对锂离子电池组质量与体积的优化。     

高温化学腐蚀加工多孔碳化硅陶瓷的表征及机理

探讨高温化学腐蚀加工SiC陶瓷工艺参数对加工质量的影响,分析SiC陶瓷的腐蚀机理。分别用失重法和Archimedes法测量试样的腐蚀速率和气孔率;用XRD、SEM、粗糙度测试仪对试样表面的形貌和结构进行表征。结果表明:随着温度和KOH浓度升高,腐蚀速率加快,温度高于碱溶液沸点时,腐蚀效果显著提高;碱溶液浓度过高会造成气孔率下降,升高温度可减缓气孔率下降;在优化的工艺参数下,高温化学腐蚀能够降低样品粗糙度,最低约为1.6μm;表面质量得到改善,轮廓支承长度率Rmr提高,Rmr(50%)达到89.70%;腐蚀温度过高或时间过长将造成晶粒脱落,导致表面质量大幅下降;此外,与机械加工试样相比,高温化学加工后的样品未出现裂纹,表面经简单清洗无反应物残留。     

Investigation of a plasma delivery system for optical figuring process

Plasma figuring process enables the correction of metre-scale optical surfaces, which has advantages such as rapid convergence to ultra-precision accuracy level, no subsurface damage, ease of upscale thanks to the conditions of operation at atmospheric. Such attributes make plasma figuring a highly competitive technology. To maintain a stable discharge of plasma for long period, a robust Plasma Delivery System (PDS) is required for large optics manufacturing. A dedicated PDS, mainly based on an L-type radio frequency (RF) network and an inductively coupled plasma (ICP) torch, had been previously proposed and designed. This study addresses the requirement for improving the robustness and securing the performance of the plasma etching. Due to the complexity of interactions of PDS parameters, single variable optimization is conducted for adjusting the impedance of the plasma torch. The PDS optimization is analysed based on ignition power demand, test repeatability and reflected power values. The results show that reflected power values are controllable within 10 W, when the RF power is supplied from 200 W up to 800 W. Finally, plasma processing is carried out on fused silica glass, using the optimum parameters of the PDS.     

Crack monitoring method based on Cu coating sensor and electrical potential technique for metal structure

Advanced crack monitoring technique is the cornerstone of aircraft structural health monitoring.To achieve real-time crack monitoring of aircraft metal structures in the course of service,a new crack monitoring method is proposed based on Cu coating sensor and electrical potential difference principle.Firstly,insulation treatment process was used to prepare a dielectric layer on structural substrate,such as an anodizing layer on 2A12-T4 aluminum alloy substrate,and then a Cu coating crack monitoring sensor was deposited on the structure fatigue critical parts by pulsed bias arc ion plating technology.Secondly,the damage consistency of the Cu coating sensor and2A12-T4 aluminum alloy substrate was investigated by static tensile experiment and fatigue test.The results show that strain values of the coating sensor and the 2A12-T4 aluminum alloy substrate measured by strain gauges are highly coincident in static tensile experiment and the sensor has excellent fatigue damage consistency with the substrate.Thirdly,the fatigue performance discrepancy between samples with the coating sensor and original samples was investigated.The result shows that there is no obvious negative influence on the fatigue performance of the 2A12-T4 aluminum alloy after preparing the Cu coating sensor on its surface.Finally,crack monitoring experiment was carried out with the Cu coating sensor.The experimental results indicate that the sensor is sensitive to crack,and crack origination and propagation can be monitored effectively through analyzing the change of electrical potential values of the coating sensor.