紧凑型自由电子激光太赫兹源研究进展

研制了一种具有两路微波馈入的新型热阴极微波电子枪和满足实验要求的主加速器增能段,介绍了该项目中的热阴极微波电子枪和主加速器的物理设计、数值模拟以及摇摆器测试结果等,并进行了初步热测实验。测得电子束能量约6.7 MeV,能散0.95%,归一化发射度13.5πmm.mrad。     

热管式吸附床制冷性能的实验研究

利用高效热管作为吸附床的传热部件,有效地提高了船用柴油机废气的热量回收。本文将热管式吸附床与传统的壳管式吸附床进行了性能对比。同时,选择氯化钙-氨作为吸附工质对,通过实验测定解吸、吸附过程的变化情况。本文的研究结果表明,采用热管式吸附床使得初始解吸和吸附速率有明显提高,从而有效缩短解吸和吸附周期,并能有效提高系统的SCP和COP。     

Comprehensive performance of a ball-milled La0.5Pr0.5Fe11.4Si1.6B0.2Hy/Al magnetocaloric composite

Due to the hydrogen embrittlement effect, La(Fe,Si)₁₃-based hydrides can only exist in powder form, which limits their practical application. In this work, ductile and thermally conductive Al metal was homogeneously mixed with La_0.5Pr_0.5Fe_11.4Si_1.6B_0.2 using the ball milling method. Then hydrogenation and compactness shaping of the magnetocaloric composites were performed in one step via a sintering process under high hydrogen pressure. As the Al content reached 9 wt.%, the La_0.5Pr_0.5Fe_11.4Si_1.6B_0.2H_y/Al composite showed the mechanical behavior of a ductile material with a yield strength of ~44 MPa and an ultimate strength of 269 MPa accompanied by a pronounced improvement in thermal conductivity. Due to the ease of formation of Fe-Al-Si phases and the several micron and submicron sizes of the composite particles caused by ball milling process, the magnetic entropy change of the composites was substantially reduced to ~1.2 J/kg· K-1.5 J/kg· K at 0 T-1.5 T.     

回热型吸附式制冷系统的实际循环与循环周期分析

1前言在吸附式制冷系统中，许多因素影响着系统的实际运行，包括运行工况、实际循环与理想循环的偏离程度、循环周期以及工质对的匹配等。要进行系统的设计，并最大限度地利用所设计的机组，就必须首先考虑这些因素。本文以连续回热型吸附式制冷系统为例，分析了系统运行的循环周期，以及实际循环偏高理想循环这两个主要因素，得出了相应的结论。2连续回热型吸附式制冷系统的实际循环和理想循环基本的回热型吸附式制冷循环包括两个吸附器，它的流程图见图1。在这个系统中，阀A、B、C、D交替开启关闭，吸附器1和吸附器2分别加热和冷却，使…     

对吸附制冷性能参数SCP物理意义的分析

评价吸附式制冷系统的主要性能指标包括COP与SCP等参数,其中SCP是单位吸附剂质量的制冷功率。SCP的计算包括按照单床运行进行计算以及按照多床循环进行计算等方式,这些计算值所代表的物理意义并不相同,本文通过对吸附式制冷不同循环方式中SCP物理意义的分析,更加明确了SCP不同计算方式所适用的场合及所代表的意义。     

一种三级自动复叠制冷系统的试验研究

本文提出一种三级自动复叠的制冷系统,搭建了相应的研究装置,采用R134 a/R23/R14混合制冷剂,对试验装置和混合制冷剂组分的优化试验。并对降温过程中制冷系统中混合制冷剂合流特性进行了分析。     

纳米铈-钨发射材料的结构与热发射性能研究

以纳米Ce—W粉末为原料制备了纳米Ce—W发射材料,利用扫描电镜和原位俄歇电子能谱等现代分析技术研究了材料的形貌、铈的分布和高温扩散、以及材料的表面性能,并采用自行研制的微机控制全自动电子发射测量装置测量了材料热发射性能。研究表明,纳米Ce-W材料晶粒细小,稀土元素铈的分布更弥散均匀,铈向表面扩散的能力增强。高温下材料表层形成了含有超额铈的活性层,纳米Ce-W材料的活性层厚度增大,超额铈的含量增多,Ce／O的活性层更厚,因此热发射性能更优异。     

High‐Performance On‐Chip Thermionic Electron Micro‐Emitter Arrays Based on Super‐Aligned Carbon Nanotube Films

An important advancement towards the realization of miniaturized and fully integrated vacuum electronic devices will be the development of on‐chip integrated electron sources with stable and reproducible performances. Here, the fabrication of high‐performance on‐chip thermionic electron micro‐emitter arrays is demonstrated by exploiting suspended super‐aligned carbon nanotube films as thermionic filaments. For single micro‐emitter, an electron emission current up to ≈20 µA and density as high as ≈1.33 A cm^?2 are obtained at a low‐driven voltage of 3.9 V. The turn‐on/off time of a single micro‐emitter is measured to be less than 1 µs. Particularly, stable (±1.2% emission current fluctuation for 30 min) and reproducible (±0.2% driven voltage variation over 27 cycles) electron emission have been experimentally observed under a low vacuum of ≈5 × 10^?4 Pa. Even under a rough vacuum of ≈10^?1 Pa, an impressive reproducibility (±2% driven voltage variation over 20 cycles) is obtained. Moreover, emission performances of micro‐emitter arrays are found to exhibit good uniformity. The outstanding stability, reproducibility, and uniformity of the thermionic electron micro‐emitter arrays imply their promising applications as on‐chip integrated electron sources.     

红外低温光学关键技术研究综述

随着红外探测技术的日趋成熟,以降低背景辐射为目的的低温光学技术已成为提高红外探测技术发展的主要途径。本文从工程应用的角度阐述了红外低温光学技术的各个要素,如低温光学系统构型选择、光学和机械结构设计、光学系统材料选择以及光学系统制冷方案设计等在低温光学处理中的设计要点。介绍了红外遥感相机和红外空间望远镜这两个红外低温光学的应用实例。最后对机载红外系统低温光学的应用提出了建议。     

冷源冷量对压缩/喷射制冷系统性能影响的实验研究

实验研究了喷射器的最优喷嘴距及在此条件下,冷凝器进水冷量对喷射器及双蒸发压缩/喷射制冷系统性能的影响,同时对双蒸发压缩/喷射制冷系统与蒸汽压缩制冷系统进行了对比研究.结果表明:喷射器引射系数随冷凝器进水冷量的增大而减小,喷射器升压比随冷凝器进水冷量的增大而增大;双蒸发压缩/喷射制冷系统COPp随冷凝器进水冷量的增加先快...