Feasibility study on optical vortex generation at Shanghai deep ultraviolet free-electron laser

Coherent light with orbital angular momentum （OAM） is of great interest. Recently, OAM light generation by coupling a relativistic electron beam with a Gaussian mode laser pulse at the high harmonics of a helical undulator has been demonstrated experimentally. In this paper, the possibility of delivering coherent OAM light at the 3rd harmonic of the Gaussian mode seed laser is discussed for the Shanghai deep ultraviolet free- electron laser （SDUV-FEL）. Considerations are given on the experiment setup, the expected performance and the possible measurement method.     

压缩空气动力汽车的可行性分析

介绍了压缩空气动力汽车的工作原理,研究了空气动力发动机工作过程的能量利用,对高压空气的储存压力进行选取,并分析了环境温度、行驶速度、汽车总质量等因素对空气动力汽车续驶里程的影响,探讨了空气动力汽车的补充能源来源、经济性、安全性、结构布置等问题,认为压缩空气动力汽车在技术上是可行的,是一种具有应用前景的绿色汽车。     

Beam dynamics optimization of very-high-frequency gun photoinjector

Nuclear Science and Techniques - The use of carbon-ion radiotherapy (CIRT) is gradually increasing. Owing to the generation of high-energy secondary neutrons during CIRT, its use presents new...     

目的层预约与多智能体协调的电梯群控调度方法

针对电梯群控调度过程中交通流和乘客目的楼层的不确定性,为克服集中式群控系统计算瓶颈问题,提出了基于目的层预约结合多智能体技术的电梯群控调度方法。首先,设计了该电梯群控调度系统的结构,分析了目的层预约的多目标评价函数;然后,提出基于模糊逻辑的电梯交通模式在线识别方案,实现实时地更新不同交通模式下对应的各控制目标的权系数;最后,结合多智能体技术具有良好的实时性和自主性的特点,将各轿厢运行控制器和群控制器映射为多个代理,通过各个代理之间协调多目标优化任务以得到平均候梯时间、平均乘梯时间及能源消耗整体最优的分布式电梯群控调度算法。     

Wakefields studies for the SXFEL user facility

Besides the original seeded undulator line,in the soft X-ray free-electron laser (SXFEL) user facility in Shanghai,a second undulator line based on self-amplified spontaneous emission is proposed to achieve 2-nm laser pulse with extremely high brightness.In this paper,the beam energy deviation induced by the undulator wakefields is numerically calculated,and 3D and 2D results agree well with each other.The beam energy loss along the undulator degrades the expected FEL output performances,i.e.,the pulse energy,radiation power and spectrum,which can be compensated with a proper taper in the undulator.Using the planned time-resolved diagnostic,a novel experiment is proposed to measure the SXFEL longitudinal wakefields.