1 上海师范大学物理系，上海 200234
2 中国科学院上海光学精密机械研究所强场激光物理国家重点实验室，上海 201800
受益于超短超强激光技术的持续迅猛发展，飞秒强激光为人类提供了全新的实验手段与极端的物理条件，使激光物质相互作用进入到一个极端非线性的强场超快新范畴，催生了大量新原理、新现象，推动了技术变革。飞秒强激光驱动的等离子体尾波场加速原理是一种具有超高加速梯度的粒子加速新原理，该技术的加速梯度可达100 GV/m，相比于传统射频加速器提高了3个数量级以上，可在厘米量级的加速长度内获得GeV量级的高品质高能电子束，极大地降低了加速器的成本，为发展新一代粒子加速技术和新型超快辐射源提供了新机遇和新途径。从飞秒强激光驱动等离子体尾波场中的电子注入、能量啁啾控制和高品质电子束产生以及基于高品质电子束的betatron X射线辐射、高能伽马射线和小型化自由电子激光这几个方面介绍了激光等离子体尾波场电子加速的若干主要研究进展，并对未来进行了展望。
1 中国人民解放军63963部队，北京 100072
2 陆军某部，北京 100072
3 四川天微电子股份有限公司，四川 成都 610200
火情探测是特种车辆灭火抑爆系统的重要组成部分，火情探测能力的高低直接影响车辆及其内部乘载员的安全。现有动力舱火情探测系统主要利用温度传感器和非成像光学火情探测器，但由于动力舱结构复杂，环境恶劣，基于温度传感器的动力舱火情探测系统由于无法实现舱内空间全覆盖安装，因此容易产生火灾漏报现象，而非成像光学火情探测器由于灵敏度过高容易产生火情误报现象，动力舱应用甚少。与现有动力舱火情探测系统不同，设计了红外成像火情探测系统，采用测温热像装置和测温显控装置，能够实现对动力舱一定目标空间内的实时温度监控，通过温度识别算法和设定预警温度阈值、报警温度阈值，实现了高温预警功能和火灾报警功能。利用标准火焰测试平台对探测系统进行了实验测试，结果表明红外成像火情探测系统的火灾响应时间小于5 s，满足国军标的要求。该系统将火灾发生后的报警提升到火灾发生前预警，能够有效避免动力舱火灾漏报问题，保护特种车辆内部人员安全。
火情探测 红外成像 动力舱 高温预警 火灾报警 fire detecting infrared imaging technology engine bay fire early warning fire alarm 红外与激光工程
2022, 51(5): 20210384
1 安徽省环境科学研究院, 安徽 合肥 230071
2 中国科学技术大学地球和空间科学学院, 中国科学院壳幔物质与环境重点实验室, 安徽 合肥 230026
利用合肥市 10 个国控站点 2019 年臭氧 (O3) 浓度数据, 采用数理统计和回归分析方法研究 O3 时空分布特征及气象因子的影响。结果表明: (1) O3小时及月均浓度均呈单峰型, 6 月份达到峰值; (2) 董铺水库和高新区站点 O3 对污染天气的贡献率相对较高, 贡献率均超过 10%; (3) 2019 年超标时次较多的站点为董铺水库和高新区, 且出现在夏季; (4) 温度、相对湿度和太阳总辐射与 O3 浓度呈正相关, 温度在 30～35°C、 相对湿度在 40%～50% 和太阳总辐射在 800～1000 W·m－2 时 O3 浓度达到最高值; 风速在 4～4.5 m·s－1 时外源输送较强烈, O3 浓度较高; 降水对 O3 前体物有清除作用, O3 浓度越高, 降水的清除作用越明显。
合肥市 臭氧 时空分布 气象因子 Hefei City ozone temporal and spatial distribution meteorological factors 大气与环境光学学报
2021, 16(4): 339
Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics
,
Shanghai Institute of Optics and Fine Mechanics
,
Chinese Academy of Sciences
,
Shanghai 201800
,
China
2 University of Chinese Academy of Sciences
,
Beijing 100049
,
China
3 Collaborative Innovation Center of IFSA
,
Shanghai Jiao Tong University
,
Shanghai 200240
,
China
4 School of Physical Science and Technology
,
ShanghaiTech University, Shanghai 200031
,
China
In this study, we investigate a new simple scheme using a planar undulator (PU) together with a properly dispersed electron beam (
beam) with a large energy spread (
) to enhance the free-electron laser (FEL) gain. For a dispersed
beam in a PU, the resonant condition is satisfied for the center electrons, while the frequency detuning increases for the off-center electrons, inhibiting the growth of the radiation. The PU can act as a filter for selecting the electrons near the beam center to achieve the radiation. Although only the center electrons contribute, the radiation can be enhanced significantly owing to the high-peak current of the beam. Theoretical analysis and simulation results indicate that this method can be used for the improvement of the radiation performance, which has great significance for short-wavelength FEL applications.
High Power Laser Science and Engineering
2018, 6(4): 04000e64
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Department of Physics, SUPA and University of Strathclyde, Glasgow G4 0NG, UK
4 IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, China
5 School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
Real-time single-shot measurement of the femtosecond electron beam duration in laser wakefield accelerators is discussed for both experimental design and theoretical analysis that combines polarimetry and interferometry. The probe pulse polarization is rotated by the azimuthal magnetic field of the electron beam and then introduced into a Michelson-type interferometer for self-interference. The electron beam duration is obtained from the region size of the interference fringes, which is independent of the pulse width of the probe laser. Using a larger magnification system or incident angle, the measurement resolution can be less than 1 fs.
120.5410 Polarimetry 350.5400 Plasmas 120.3180 Interferometry Chinese Optics Letters
2018, 16(7): 071202
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Collaborative Innovation Center of IFSA (CICIFSA), Shanghai Jiao Tong University, Shanghai 200240, China
4 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
5 School of Physical Science and Technology, ShanghaiTech University, Shanghai 200031, China
Beam quality degradation during the transition from a laser wakefield accelerator to the vacuum is one of the reasons that cause the beam transport distortion, which hinders the way to compact free-electron-lasers. Here, we performed transition simulation to initialize the beam parameters for beam optics transport. This initialization was crucial in matching the experimental results and the designed evolution of the beamline. We experimentally characterized properties of high-quality laser-wakefield-accelerated electron beams, such as transverse beam profile, divergence, and directionality after long-distance transport. By installing magnetic quadrupole lenses with tailored strength gradients, we successfully collimated the electron beams with tunable energies from 200 to 600 MeV.
020.2649 Strong field laser physics 110.2970 Image detection systems Chinese Optics Letters
2018, 16(4): 040201
