共查询到20条相似文献,搜索用时 93 毫秒
1.
低温装置中温度测量的热沉问题 总被引:2,自引:0,他引:2
文中讨论了低温装置中的热沉问题。为减少因电引线导热对温度计的热负荷 ,提高温度测量的精度 ,在温度计的引线中加入热沉将是非常必要而且有效的手段。文中解决了不同边界条件下所需的热沉长度的求解问题 ,并讨论了其实际应用 相似文献
2.
3.
4.
5.
����ܽ��£����ٷɣ�κ���죬�� �� 《核聚变与等离子体物理》2018,38(3):287-292
采用理论计算和有限元实体模型的方法,对HL-2M装置低温冷凝泵及与其相连接的真空穿透结构进行了温度分布和液氦管热负荷分析。结果显示,低温冷凝泵中液氦管的热稳态热负荷为5.45W,粒子沉积的热负荷为75.68W,真空穿透部分的热负荷为5.04W。所得结果为后续的热应力分析、低温泵流速控制和低温系统的设计提供了参考。 相似文献
6.
7.
采用理论计算和有限元实体模型的方法,对HL-2M装置低温冷凝泵及与其相连接的真空穿透结构进行了温度分布和液氦管热负荷分析。结果显示,低温冷凝泵中液氦管的热稳态热负荷为5.45W,粒子沉积的热负荷为75.68W,真空穿透部分的热负荷为5.04W。所得结果为后续的热应力分析、低温泵流速控制和低温系统的设计提供了参考。 相似文献
8.
9.
10.
11.
The factors affecting the feasibility of cryogenically cooled CMOS are reviewed. This approach becomes more attractive as CMOS feature sizes shrink below 250?nm where chip performance is limited by interconnect characteristics. The impact of interconnects is demonstrated using a methodology for estimating interconnect-limited CMOS performance. The cryogenic behavior of normal and superconducting interconnects is reviewed. Cooling the best normal interconnect metals such as Al or Cu to 77?K can produce 9×lower resistivity. High-temperature superconductors can produce lower resistance at GHz clock frequencies, but would be difficult to produce on low dielectric substrates compatible with silicon technology. Performance doubling has been demonstrated for CMOS circuits operating at liquid nitrogen temperature. Comparable performance improvements may be expected down to below 100?nm if process technology is adjusted appropriately. In addition, dramatic increases in DRAM storage times result from exponential decreases in subthreshold leakage currents. Circuit reliability should increase correspondingly, apart from hot-carrier induced degradation. Thermally efficient packages and refrigerators are required for cryogenic CMOS. Microchannel heat exchangers can produce thermally efficient cryogenic packages. However, thermodynamic limits to refrigerator performance may make operation at higher cryogenic temperatures more attractive. 相似文献
12.
为了研究低温条件下Yb:YAG放大器的增益和热特性,搭建了一套液氮冷却的低温放大器,开展了实验研究。测量了不同泵浦强度下的小信号增益以及低温和常温下的介质热致波前畸变。结果表明:低温条件下,可以用更少的泵浦能量得到高于常温的增益;常温下泵浦电流200A、脉冲宽度1200μs的小信号增益为1.59;低温下泵浦电流200A、脉冲宽度400μs的小信号增益为1.82,光光效率显著提高。自发辐射放大(ASE)问题在低温下更加显著,采用短脉冲泵浦有利于降低ASE的影响。低温的热管理效果较常温有显著提高,可以在更高的平均功率下运行。 相似文献
13.
Nikolai I. Avdievich Gary J. Gerfen 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,153(2):178-185
The design, construction, and performance of a multifrequency pulsed EPR and ENDOR probe for use at cryogenic temperatures are described. Interchangeable resonators based on a folded strip line design allow variation of the resonance frequency over a range of 5-11 GHz. Variable coupling to the resonator is achieved capacitively via a simple mechanical adjustment which is thermally and mechanically stable. The entire assembly is robust and easily fabricated. Common methods of analyzing the resonator parameters such as the Q-factor and coupling coefficient are discussed quantitatively. Probe performance data and multifrequency pulsed ENDOR spectra are presented. 相似文献
14.
15.
The controllable synthesis and characterization of novel thermally stable silver-based particles are described. The experimental approach involves the design of thermally stable nanostructures by the deposition of an interfacial thick, active titania layer between the primary substrate (SiO2 particles) and the metal nanoparticles (Ag NPs), as well as the doping of Ag nanoparticles with an organic molecule (Congo Red, CR). The nanostructured particles were composed of a 330-nm silica core capped by a granular titania layer (10 to 13 nm in thickness), along with monodisperse 5 to 30 nm CR-Ag NPs deposited on top. The titania-coated support (SiO2/TiO2 particles) was shown to be chemically and thermally stable and promoted the nucleation and anchoring of CR-Ag NPs, which prevented the sintering of CR-Ag NPs when the structure was exposed to high temperatures. The thermal stability of the silver composites was examined by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Larger than 10 nm CR-Ag NPs were thermally stable up to 300 °C. Such temperature was high enough to destabilize the CR-Ag NPs due to the melting point of the CR. On the other hand, smaller than 10 nm Ag NPs were stable at temperatures up to 500 °C because of the strong metal-metal oxide binding energy. Energy dispersion X-ray spectroscopy (EDS) was carried out to qualitatively analyze the chemical stability of the structure at different temperatures which confirmed the stability of the structure and the existence of silver NPs at temperatures up to 500 °C. 相似文献
16.
液氦容器是浸泡式超导涡流制动装置稳定运行不可或缺的部件, 其漏热损耗和结构强度关系着内部超导磁体能否安全稳定的工作. 针对超导涡流制动装置的液氦容器的各类漏热进行了分析计算, 详细讨论了超导线圈励磁过程中对不同壁厚的液氦容器产生的涡流损耗, 并采用 Ansys 有限元分析软件对不同壁厚液氦容器的强度进行了计算, 结合漏热及强度计算结果获得了最优的液氦容器壁厚参数. 结果表明4 mm 壁厚下的液氦容器总漏热在励磁速度为90 A/s 时可达1 .87 W, 液氦容器在各类综合力作用下的最大应力为393 MPa, 最大变形为2.2 mm,可满足所选材料的漏热及强度需求, 为超导涡流制动器装置总体设计提供了有力保证. 相似文献
17.
18.
介绍的高效低温传热方法主要包括 :自然循环冷却法和基于自然循环预冷及低温热管的高效低温冷却方法。自然循环冷却法的特点是在大温差条件下实现物体的快速冷却。一旦被冷却物体到达或接近低温液体的温度 ,将产生循环动力不足的情况 ,必须采用诸如气体引射或容器自增压等方法加以解决。而低温热管的特点在于能在小温差条件下 ,传递大量的热能。文中将自然循环预冷法及低温热管技术有机结合 ,综合自然循环和低温热管的优点 ,取长补短 ,既可以在很短的时间内使被冷却物体的温度降低下来 ,又可以保证被冷却物体的温度波动较小。文中还详细给出了基于自然循环预冷及低温热管的高效低温传热单元的设计及试验结果 相似文献
19.
自主设计了低温吸收池其温度可以从室温到100K之间连续调节,在可调节温度区间内可以稳定在任意一个目标温度,温度的稳定性为ΔT<±1K。对低温吸收池内部结构作了详细的说明,并对温度的稳定性进行测试。用于测量1.65μm处甲烷低温吸收光谱,给出6 039.70cm-1处甲烷在296,248,198和176K低温吸收光谱的特性,并根据可调节低温吸收池的温度可调节性测量了甲烷吸收光谱在6 039.657 9cm-1处的自加宽温度依赖系数n。 相似文献
20.