几种液体金属自由表面的MHD不稳定性实验研究

介绍了在核工业西南物理研究院的液态金属实验回路(LMEL)上获得的几种可供液态偏滤器-限制器系统选用的液体自由表面的磁流体动力学(MHD)效应不稳定性的实验结果。实验发现：自由表面射流在穿越梯度横磁场时射程变短、截面变扁平,但MHD效应稳定,调节射流与磁场的夹角可以控制射流的流动特性;自由表面膜流MHD效应存在三种现象,即层流、溪状流和湍流。层流是由多束射流打到固体表面产生的(简称“射-膜流”),从MHD效应角度考虑,“射-膜流”将是四种可选液态偏滤器-限制器系统的液体自由表面形式中最佳的选择。同时,探讨了从物理的角度来理解四种自由表面形式的MHD效应的现象。     

Design and Application of a Near Field Microwave Antenna for the Spin Control of Nitrogen-Vacancy Centers

Controlled manipulation of the electron spin by means of a microwave field is investigated. The near magnetic field generated by a copper wire antenna is measured experimentally and simulated theoretically, and the optimum antenna length and position are obtained. By measuring the change in the fluorescence of nitrogen-vacancy （N-V） centers in diamond after excitation with a 532 nm continuous wave laser at room temperature, it is verified that the spin of the N-V center can be effectively controlled by the microwave field.     

Magnetic Manipulation of Massless Dirac Fermions in Graphene Quantum Dot

We have theoretically analyzed the quasibound states in a graphene quantum dot (GQD) with a magnetic flux Φ in the centre. It is shown that the two-fold time reversal degeneracy is broken and the quasibound states of GQD with positive/negative angular momentum shifted upwards /downwards with increasing the magnetic flux. The variation of the quasibound energy depends linearly on the magnetic flux, which is quite different from theparabolic relationship for Schrödinger electrons. The GQD's quasibound states spectrum shows an obvious Aharonov-Bohm (AB) oscillations with the magnetic flux. It is also shown that the quasibound state with energy equal to the barrier height becomes a bound state completely confined in GQD.     

国内首次超导高频系统束流调试及高功率试验

2004—2007年BEPC高频系统从常温腔改建到超导腔, 逐渐解决了改频的物理问题和超导技术的工程难题, 实现了与国际先进技术接轨, 并按期保质完成了工程、调束任务. 高频系统是BEPCⅡ工程首个吸收国外超导技术、自主完成集成和调试成功的大型装置; 2006年7月国内首次超导高频大功率试验成功; 2006年11月完成系统联调, 按期投入BEPCⅡ首轮调束; 同年12月首次投入同步辐射运行; 2007年2至5月, 东、西两套超导高频系统在1MV以上的加速电压均已实现正/负电子1.89GeV注入积累和110/114mA对撞; 在同步辐射运行中, 逐渐达到2.5GeV/250mA、束流功率100kW, 接近国外同类机器水平; 束流试验证明两套高频系统的     

Microstructure of epitaxial superconductive YBa2Cu3O7 thin films prepared at different deposition rates

A study is reported on the growth mechanism of YBa₂Cu₃O₇ with different growth speeds by high resolution transmission microscopy (HRTEM) and analysis of the interface and thin film microstructure. Two thin films were synthesized by pulse laser deposition on [100], miscut 5°, SrTiO₃ substrate at 820 °C, one with a pulse laser frequency of 1 Hz and one with 6 Hz. Cross-sections were studied by an H-9000 NAR HRTEM along the [010] direction. The growth process of the sample made at 1 Hz was as follows. First, distorted step flow growth occurred on a step-mediated substrate surface of 3–4 cells thickness. Second, about a 15 nm thickness of island shape growth becomes superimposed on the area of the step flow layer. Finally, thin film growth occurred but with growth fluctuation. The sample made at 6 Hz showed the characteristics of island growth; the growth area of island or ball shape was of small size and dense distribution, and seemed to be a confused mosaic stack. The influence of growth speed on YBCO epitaxial film microstructure was studied explicitly by HRTEM.     

ITER聚变功率关闭系统的一种阀门箱结构的有限元分析

用ANSYS软件对ITER聚变功率关闭系统(FPSS)的一种阀门箱的结构在ITER各种典型荷载组合下的应力和应变进行了有限元分析,并遵照ASME及ITER标准对分析结果进行了评判。结果表明这种阀门箱结构能够满足ITER的设计要求。     

聚变堆高热流部件超汽化换热实验研究

搭建了常压水超汽化实验回路(HVL-Ⅰ),采用平面激光诱导荧光(PLIF)、高速摄影、微距摄影、粒子成像测速(PIV)等先进测量技术,开展聚变堆面对等离子体部件(第一壁、偏滤器)在高热流过冷沸腾工况下强化换热特性实验研究。选择三角形和矩形翅片的铬锆铜超汽化样件,实验工况为常压室温(296K),若丹明B 水溶液流速 0.3～0.5m•s⁻¹ 连续可调,热流密度～5MW•m⁻²。实验结果表明同等工况下,矩形翅片比三角形翅片换热效果显著增强,性能提升约30%～50%。微距摄影显示翅根涡流形态保持时间越短,越有利于小汽泡充分扩散,从而使换热得到强化。     

在强辐射阻尼存在下完全反转态的线型

在180°脉冲加z方向脉冲梯度场作用后,采样得到90%水样的自由感应衰减信号,其具有几乎完整的双曲正割函数特征,并通过付立叶变换得到其频谱,发现其具有强烈的震荡特征,这与通常用不完善的180°单脉冲观测到的相位畸变有所不同,并且发现这种强震荡只有在强辐射阻尼存在下以及θ₀非常接近180°时才能观测到.在辐射阻尼线型理论基础上,合理的理论计算已进行,我们得到了与实验观测相当一致的结果.     

掺铒光纤激光器自混合理论与微振动位移测量

利用线形掺铒光纤激光器搭建了一种新型光纤传感测量系统来测量微振动位移.采用条纹计数法分析自混合干涉信号,实验显示扬声器的振幅与驱动电压成很好的线性关系.该实验装置结构简单、成本低.实验结果表明,用该传感系统来进行振动位移测量,信号稳定,方法简单、迅速.