Optimization and numerical simulation for the extraction system of the H- multicusp ion source

A new ion source has been designed and manufactured for the CYCLONE30 accelerator, which has a much advanced performance compared with the original. It is expected that the newly designed ion source extraction system will transport a very large percentage of the beam without deteriorating the beam optics, which is designed to deliver an H- beam at 30 keV. The accelerator assembly consists of three circular aperture electrodes made of copper. The simulation study was focused on finding parameter sets that raise the beam perveance as large as possible and which reduce the beam divergence as low as possible. Ion beams of the highest quality are extracted whenever the half-angular divergence is minimum, for which the perveance current intensity and the extraction gap have optimum values. The triode extraction system is designed and optimized by using CST software （for Particle Beam Simulations）. The physical design of the extraction system is given in this paper. From the simulation results, it is concluded that it is possible to achieve this goal by decreasing the thickness of the plasma electrode, shortening the first gap, and adjusting the acceleration electrode voltage.     

An Easily Switchable Dual-Wavelength Passively Mode-Locked Erbium Fiber Laser

A simple scheme of switchable dual-wavelength passively mode-locked fiber laser is demonstrated. The laser can be flexibly switched among different mode-locked states simply by tuning the cavity loss while keeping all the other cavity parameters fixed. As the cavity loss increases, the mode-locked fiber laser operates at the long-wavelength, dual-wavelength, and short-wavelength states, successively. In addition, these states can be conveniently switched without losing the mode-locked operation and the switching process is reversible as the cavity loss decreases. The mechanism is qualitatively explained by the balance between the fiber gain and the cavity loss.     

Design and Fabrication of Six-Channel Complex-Coupled DFB Quantum Cascade Laser Arrays Based on a Sampled Grating

We designed and fabricated a six-channel complex-coupled distributed feedback （DFB） quantum cascade laser arrays based on a sampled Bragg grating. The six-channel DFB laser arrays exhibit a linear tuning range of 74nm centered at a wavelength of 7.55μm at room temperature. Robust single-mode emission with a side mode suppression ratio about 20 dB was observed, even at full power. The used sampled grating and reflectivity coating on the back facet lead to the peak output power varying from 55 to 82 m W with a small difference in slope efficiency from 100 to 128mW/A.     

Strong and broadband terahertz absorber using Si02-based metamaterial structure

We design and experimentally demonstrate a broadband metamaterial absorber in the terahertz （THz） band based on a periodic array of aluminum （A1） squares with two different sizes. A thin silicon dioxide （SiO2） film rather than a conventional polyimide （PI） layer is used as a dielectric spacer to separate A1 squares from the platinum （Pt） ground plane in our design, which significantly improves the design precision and the feasibility of the device fabrication. The combination of different sizes of AI squares gives rise to an absorption bandwidth of over 210 GHz with an absorption of over 90%. Our results also show that our device is almost polarization-insensitive. It works very well for all azimuthal angles with an absorption of beyond 80%.     

离轴全反射施密特系统设计

为满足紫外宽光谱大视场焦平面光学成像系统的设计要求,研究了全反射施密特光学系统.分析了球面反射镜曲率中心波前,推导了透射及反射施密特校正板方程.为避免光线被遮挡,设计了离轴全反射施密特光学系统.在宽光谱(240~950nm)大视场(±5°)离轴全反射施密特系统中,当λ=0.24μm,u′m=5°时,Δf≤0.031 5mm,探测器控制在焦深范围内,光学系统成像质量达到了衍射极限.该施密特光学系统设计方法适用于宽波段高分辨率紫外成像系统.     

Virtual topology design scheme with energy efficiency for IP over elastic optical networks

The rapid growth of the Internet raises the importance of resource planning of Internet protocol（IP） over elastic optical networks（EONs）, which is a challenging task due to more complex and obscure physical constraints of it. Compared with network cost, the power consumption may eventually become the barrier to the expansion of the Internet. We present an energy-efficient virtual topology design（VTD） scheme for IP over EON. We explicitly explain and analyze the mixed integer linear programming model and the heuristic algorithm for this scheme. Numerical results show that the proposed VTD scheme can significantly save power consumption.     

增程式电动汽车动力总成参数匹配设计

增程式电动汽车作为一种新型节能环保型汽车,是传统内燃机汽车向纯电动汽车过渡的一种车型;根据动力传动系统的设计原则和设计目标,基于铃木奥拓燃油汽车改装设计了增程式电动汽车的动力传动系统的参数匹配方法,根据电动汽车基本参数及其控制目标,对动力总成系统的关键零部件进行了匹配设计;匹配结果表明:电动机的额度电压为60 V,最高转速为4 000 r/min,额定功率为8 kW,额定转矩为40.43 N·m,峰值功率为11 kW,最大扭矩为80.86 N·m;增程器采用马勒增程器和两缸直列四冲程发动机;动力电池组采用磷酸铁锂子电池,单组额定容量为80 Ah、总电压为96 V;对于指导增程式电动汽车的开发、提高汽车性能和安全性,以及对于电动汽车底盘集成控制系统的开发都具有重要的工程应用意义。     

一种适用于极端高温条件的六面顶压机实验组装

参考活塞-圆筒高压设备常用的实验组装中热电偶的布局方式,设计了一种适用于极端高温条件的六面顶压机实验组装。在新的实验组装中,热电偶不再横穿石墨加热炉,而是在石墨炉中纵向分布,从石墨炉顶端横向引出。与传统的六面顶压机实验组装相比,这种新组装具有更强的高温稳定性。测试表明:在5GPa压力下,1 600℃时实验组装的稳定性能够保持48h以上,1 800℃时能够保持约30h,2 000℃时能够保持约10h。温度梯度测试表明,当组装的中心温度为1 454℃时,在组装中央4mm的范围内平均温度梯度仅有27℃/mm,低于中心温度的2%。较长的保温时间以及低温度梯度能进一步提高六面顶压机在地球科学研究领域中的应用。     

用He离子诱导的裂变激发函数探测核摩擦强度(英文)

随机模型被用于分析3He+197Au,3He+208Pb和3He 186W反应测量的裂变激发函数。提取的鞍点前摩擦强度约为4×1021s-1。揭示了能级密度参数的大小在约束核摩擦强度中的作用。计算表明,高激发条件能能显著增强裂变截面对核耗散的敏感性。     

The separability of two-mode Gaussian state under amplification and symmetric damping

The performances of a two-mode Gaussian state under parametric amplification, symmetric amplitude damping and thermal noise are studied. The time-dependent complex correlation matrix of the state in evolution is given. The separability of the final two-mode Gaussian state is examined under symmetric amplification and asymmetric amplification separately.