Theory on single molecule-photon cryocooler

The micro mechanism of anti-Stokes fluorescent cooling was investigated on molecular or ionic scale. A new conception of single molecule-photon cryocooler (SMPC) was given, and the smallest cryocooler in the world was predicted. We described SMPC and its running principle in detail. The quantum transition processes of SMPC and the largest cooling coefficient that SMPC can get in an optical transition were given. Also we studied the random property of SMPC in cooling processes. The thermodynamic behavior of single Yb³⁺ ion as a photon cryocooler was imitated.     

Analysis of ultrasound-assisted convective heating/cooling process: Development and application of a Nusselt equation

In this study, the convective heating/cooling process assisted by US irradiation is analyzed with the aims of developing a new convective heat transfer correlation. Heat transfer experiments were conducted with different copper machined geometries (cube, sphere and cylinder), fluid velocities (0.93–5.00 × 10⁻³ m/s), temperatures (5–60 °C), and US intensities (0–6913 W/m²) using water as heat transfer fluid. The Nusselt (Nu) equation was obtained by assuming an apparent Nu number in the US-assisted process, expressed as the sum of contributions of the forced convection and cavitation-acoustic streaming effects. The Nu equation was validated with two sets of experiments conducted with a mixture of ethylene glycol and water (1:1 V/V) or a CaCl₂ aqueous solution (30 g/L) as immersion media, achieving a satisfactory reproduction of experimental data, with mean relative deviations of 17.6 and 17.8%, respectively. In addition, a conduction model with source term and the proposed correlation were applied to the analysis of US-accelerated heating kinetics of dry-cured ham reported in literature. Results demonstrated that US improves heating of ham slices because of the increased heat transfer coefficients and the direct absorption of US power by the foodstuff.     

Simulation and experiment of the cooling effect of trapped ion by pulsed laser

We investigate the process of pulsed laser cooling using a self-constructed molecular dynamics simulation(MDSimulation) program. We simulate the Doppler cooling process and pulsed laser Doppler cooling process of a single ~(40)Ca~+ ion, and the comparison with the experimental results shows that this self-constructed MD-Simulation program works well in the weak laser intensity situation. Furthermore, we analyze the pulsed laser Doppler cooling process of a single ~(27)Al~+ ion. This program can be used to analyze the molecular dynamic process of various situations of Doppler cooling in an ion trap, which could give predictions and experimental guidance.     

Numerical analysis of motional mode coupling of sympathetically cooled two-ion crystals

A two-ion pair in a linear Paul trap is extensively used in the research of the simplest quantum-logic system; however,there are few quantitative and comprehensive studies on the motional mode coupling of two-ion systems yet. This study proposes a method to investigate the motional mode coupling of sympathetically cooled two-ion crystals by quantifying three-dimensional(3 D) secular spectra of trapped ions using molecular dynamics simulations. The 3 D resonance peaks of the ~(40)Ca~+ – ~(27)Al~+ pair obtained by using this method were in good agreement with the 3 D in-and out-of-phase modes predicted by the mode coupling theory for two ions in equilibrium and the frequency matching errors were lower than 2%.The obtained and predicted amplitudes of these modes were also qualitatively similar. It was observed that the strength of the sympathetic interaction of the ~(40)Ca~+ – ~(27)Al~+ pair was primarily determined by its axial in-phase coupling. In addition,the frequencies and amplitudes of the ion pair's resonance modes(in all dimensions) were sensitive to the relative masses of the ion pair, and a decrease in the mass mismatch enhanced the sympathetic cooling rates. The sympathetic interactions of the ~(40)Ca~+ – ~(27)Al~+ pair were slightly weaker than those of the ~(24)Mg~+– ~(27)Al~+ pair, but significantly stronger than those of ~9Be~+ – ~(27)Al~+ . However, the Doppler cooling limit temperature of ~(40)Ca~+ is comparable to that of ~9Be~+ but lower than approximately half of that of ~(24)Mg~+. Furthermore, laser cooling systems for ~(40)Ca~+ are more reliable than those for ~(24)Mg~+and ~9Be~+ . Therefore, ~(40)Ca~+ is probably the best laser-cooled ion for sympathetic cooling and quantum-logic operations of ~(27)Al~+ and has particularly more notable comprehensive advantages in the development of high reliability, compact, and transportable ~(27)Al~+ optical clocks. This methodology may be extended to multi-ion systems, and it will greatly aid efforts to control the dynamic behaviors of sympathetic cooling as well as the development of low-heating-rate quantum logic clocks.     

环形磁场金属等离子体源冷却流场的数值模拟与优化

环形磁场金属等离子体源作为一种全新的等离子体源结构,可用于产生高度离化、无大颗粒、高密度的离子束流,但传统流道结构不能保证其高效、均匀散热,大功率工作时可能引起密封胶圈的烧蚀失效,需对其冷却流场进行优化设计.利用Solidworks Flow Simulation软件对等离子体源冷却流道进行模拟,分析出入水孔分布角度、孔数、孔径以及入水孔高度对冷却效果的影响规律,并对流道结构参数进行优化.结果表明,增大水孔的周向分布范围,有利于提高散热的均匀性;入水孔设置在结构上层有利于减少冷却水的温度分层现象,使铜套和密封胶圈都处于较好的冷却状态;适当减小孔径有利于增大冷却水射流速度,增大湍流程度强化传热,提高换热效率.优化后的流场结构可以提高冷却水的利用率,在相同流量条件下获得更好的冷却效果,改善等离子体源的放电稳定性,为环形磁场金属等离子体源的冷却结构设计提供理论依据.     

高速气流中激光加热平板数值模拟与分析

 采用流固耦合方法,数值模拟了高速流场中激光作用下来流速度对平板温度分布的影响。结果表明:无激光辐照时,高速气流中平板有较高的气动生热平衡温度,且平板-气流之间的换热系数随来流速度增大而增大;在平板前沿换热系数增长最快,沿平板长度方向增速趋于平缓。分析了激光辐照时高速气流中激光加热平板的温度分布情况,考察了来流速度不同时,气动生热、散热和激光辐照对平板温度的影响,给出了激光辐照后的温升情况和温度分布,分析了在不同速度来流下,对流散热、摩擦生热和激光加热之间的竞争关系,结果表明,平板温度具体分布主要是加热过程竞争的结果。     

迫流冷却二极NbTi超导磁体的研究

首先介绍了导体的测试结果;其次,为评估迫流冷却的二极NbTi超导磁体正常工况下对液氦产生的低温热负荷,基于surf152表面效应单元对线圈盒进行了辐射传热分析;此外,为减小通过线圈盒支撑的传导热负荷并且提高其机械强度,依据线圈盒支撑杆的设计尺寸,提出使用玻璃纤维经过三维编织的各向异性复合材料-G10制作线圈盒支撑杆,从...     

非链式脉冲DF激光器的关键技术（英文）

基于化学反应的非链式脉冲DF激光器是产生3.5～4.1μm波段的有效相干辐射光源,具有存储能量水平高等优点。这些优点使得该激光器倍受中红外领域激光研究者的重视。为了更好地提高非链式脉冲DF激光器的输出性能,研制高能量水平的DF激光器,本文详细介绍了自引发大体积放电技术、混合气体配比技术、循环冷却技术等DF激光器关键技术,重点介绍了自引发大体积放电技术。这几种技术将为研制高性能DF激光器提供理论指导。     

反斯托克斯荧光制冷的研究进展与综述

反斯托克斯荧光制冷 (Anti StokesFluorescentCooling)也被称为激光制冷 (LaserCooling)。自 1 995年以来 ,该项研究取得了飞速的发展。目前 ,人们利用激光制冷的方法已经得到了比家用冰箱冷冻室还低的温度 ,并能够利用半导体量子阱材料得到低于液氮温区的降温。由于这项技术具有全光性 ,它的制冷器具有体积小、重量轻、无电磁辐射、无振动、无噪声等特点 ,因此也就具有了非常诱人的应用前景和符合军事、空间、集成光学、微电子、医学等领域的特殊要求 ,而被国外研究者所重视。做为一项基本技术 ,激光制冷研究的突破必然会导致许多对温度有特殊要求的高技术实用化 ,推动那些领域向前发展。本文详细地介绍了反斯托克斯荧光制冷研究的历史和最新进展 ,详细地介绍了该项研究中的方法和理论。着重介绍了激光制冷的热力学限制、发光过程的热力学理论 ,探讨激光制冷产生的机制和制冷理论。最后 ,对激光制冷器的发展前景和设计依据进行了讨论 ,尝试性地探讨了线圈型制冷器、用于芯片的制冷器和单分子 光子泵型制冷器的应用考虑。     

气膜冷却计算中湍流黏性系数的修正

燃气轮机高温叶片气膜冷却中的复杂涡系结构使得流动传热很难被准确预测.本文基于平板气膜冷却数值和实验研究结果,指出雷诺平均算法中常用的湍流模型在射流侧向输运和二次涡的捕捉上具有相当的局限性.文中对湍流黏性系数提出了各向异性对数率涡黏模型(ALEV模型)修正,基于ALEV模型修正后的湍流模型增强了射流的侧向输运,减弱了二次...