Macroscopic quantum coherence in a single molecular magnet and Kondo effect of electron transport

We report a Kondo-effect study of electron transport through a quantum dot with embedded biaxial single-molecule magnet based on slave boson mean-field theory and non-equilibrium Green-function technique. It is found the macroscopic quantum coherence of molecule-magnet results in the Kondo peak split of differential conductance due to interaction between electron and molecular magnet. It is also demonstrated that both the peak height and position can be controlled by the sweeping magnetic field and polarization of ferromagnetic electrodes. The characteristic peak split may be used to identify the macroscopic quantum coherence and develop molecule devices.     

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...     

Hard magnetic properties of anisotropic Sm-Fe-N magnets produced by compression shearing method

Anisotropic Sm-Fe-N bulk magnets were produced by the compression shearing method using a hardened steel plate and a tungsten-carbide (WC) plate. It was found that the magnets retained the original Sm₂Fe₁₇N₃ phase structure without any appreciable decomposition of the Sm₂Fe₁₇N₃ phase. The anisotropic Sm-Fe-N bulk magnet produced using a WC plate had a higher density and higher crystallographic alignment of the Sm₂Fe₁₇N₃ phase than that produced using a hardened steel plate, and exhibited high maximum energy products of 228 kJ/m³ with a high coercivity of 0.88 MA/m.     

电磁阻尼落体运动实验仪研究

设计了电磁阻尼落体实验仪,可以定量研究受电磁阻尼的落体运动过程,在不同的阻尼条件下验证速度和路程公式,并计算出阻尼系数.     

ECR离子源六极永磁体的设计研究

分别从材料、结构、尺寸等方面全面地研究了Halbach结构六极永磁铁的设计方法.针对个别磁块可能存在的退磁问题给出了相应的解决方案.通过优化结构,使六极磁铁在离子源等离子体弧腔内壁产生的磁场达到最大.用POISSON,PERMAG,TOSCA等多个磁场模拟程序计算模拟了六极磁场的大小与分布,并给出了一些相应的曲线     

一种新的永久周期磁铁聚焦的高功率宽带放大器

 提出了一种新的高功率宽带放大器，它由速调管和自由电子脉塞组成，用永久周期磁铁聚焦。研究了这种器件的电子束聚焦、群聚和辐射。在速调管提供一阶调制系数为30%，波导管的半径1.51cm，摇摆器的磁场振幅0.16T，周期7.92cm，电子束的电压490kV，电流50A和半径0.368cm的条件下，预估这种器件的辐射波频率为11.4GHz，输出辐射功率为18MW，输出辐射带宽为44%。     

Adaptive synchronization of chaos in permanent magnet synchronous motors based on passivity theory

An adaptive synchronization control method is proposed for chaotic permanent magnet synchronous motors based on the property of a passive system. We prove that the controller makes the synchronization error system between the driving and the response systems not only passive but also asymptotically stable. The simulation results show that the proposed method is effective and robust against uncertainties in the systemic parameters.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

永磁体等效磁矩的测量

在磁技术应用中，对永磁材料的主要磁性参数的研究及测量已成为人们关注的问题之一．本文提出通过测量磁场从而确定永磁体磁矩的一种简便方法，并就测量所涉及的有关问题作了讨论．     

Clinotron的初步理论和数值模拟

在理论分析的基础上,模拟研究了微电真空太赫兹器件Clinotron。求解了色散方程,获得该器件的基本结构参数和性能参数;在考虑空间电荷场和电子回旋运动的情况下,得出能使器件内片状束稳定传输的周期永磁聚焦的磁场条件;利用3维全电磁粒子模拟程序对Clinotron进行了初步模拟以及优化。数值模拟结果表明:当输入电压为4.5 kV、发射束流大小为190 mA、输入电功率为855 W时, 运行频率为218 GHz的Clinotron的输出平均功率40 W,功率转换效率达4.68%。