Author: Feng, C.
Paper Title Page
Status of Dalian Coherent Light Source  
  • W.Q. Zhang, D.X. Dai, G.L. Wang, G.R. Wu, X.M. Yang
    DICP, Dalian, People's Republic of China
  • S. Chen, C. Feng, D. Wang, M. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  Funding: DCLS is a joint project of Dalian Institute of Chemical Physics (DICP) and Shanghai Institute of Applied Physics (SINAP), CAS. It is supported by National Natural Science Foundation of China (21127902)
A Free Electron Laser with high brightness, ultrafast laser pulses in the vacuum ultraviolet (VUV) wavelength region is an ideal light source for excitation of valence electrons and ionization of molecular systems with very high efficiency. it is quite helpful for studies of important dynamic processes in physical, chemical and biological systems. Dalian Coherent Light Source (DCLS) plans to deliver optical beam from 50-150nm in picoseconds or 100 femtoseconds for such research. High gain harmonic generation is the perfect choice in VUV FEL for narrow bandwidth, stable power and low cost due to fewer undulators. After eight months of installation and machine commissioning, a 300-MeV electron beam was achieved with peak current of more than 300A, and the emittance was less than 1.5 mm.mrad. The FEL power for individual pulse at 133nm approached more than 200uJ with 266nm seed laser on Jan. 2017. The gain curve and spectrum of HGHG & SASE FEL was measured, and tapering undulator helps increase the power by almost 100% when the FEL output saturated. The user experiment will start on June 2017. It is open for good proposals from the whole world.
Design Study and Preparations for the Echo-30 Experiment at SXFEL  
  • C. Feng, S. Chen, H.X. Deng, B. Liu, D. Wang, X.T. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • D. Xiang
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  In this work, design study and hardware preparations for the echo-30 experiment at the SXFEL test facility are presented. With the realistic parameters of the SXFEL, start-to-end simulations considering various three-dimensional effects have been carried out, and the simulation results demonstrate that a single-stage EEHG can generate high-power soft x-ray radiation pulses with narrow bandwidth directly from UV seed lasers. We also show the preparations of the seed lasers, undulators and photon beam diagnostics for the echo-30 experiment at the SXFEL.  
MOP023 Two-Color Soft X-Ray Generation at the SXFEL User Facility Based on the EEHG Scheme 1
  • Z. Qi, C. Feng, B. Liu, W.Y. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  We study the two-color soft x-ray generation at the Shanghai soft X-ray Free Electron Laser (SXFEL) user facility based on the echo-enabled harmonic generation (EEHG) scheme. Using the twin-pulse seed laser with different central wavelengths, an preliminary simulation result indicates that two-color soft x-ray FEL radiation with wavelengths at 8.890 nm and 8.917 nm can be obtained from the ultraviolet seed laser. The radiation power is about 600 MW and the time delay is adjustable.  
MOP024 Simulation and Optimization for Soft X-Ray Self-Seeding at SXFEL User Facility 1
  • K.Q. Zhang, C. Feng, D. Wang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  The simulation and optimization studies for the soft x-ray self-seeding experiment at SXFEL have been presented in this paper. Some critical physical problems have been intensively studied to help us obtain a more stable output and a clearer spectrum. The monochromator is optimized considering various unideal conditions such as the reflection rate, diffraction rate and the roughness of the grating and the mirrors. An integrated self-seeding simulation is also presented. The calculation and simulation results show that the properties of the self-seeding can be significantly improved by using the optimized design of the whole system and the evaluation of grating monochromator shows that the presented design is reliable for soft x-ray self-seeding experiment at SXFEL.  
Extending the Photon Energy Coverage of an X-Ray Self-Seeding FEL via the Reverse Taper Enhanced Harmonic Generation Technique  
  • K.Q. Zhang, C. Feng, D. Wang
    SINAP, Shanghai, People's Republic of China
  In this paper, we propose a novel method that combines the reverse undulator taper and harmonic generation techniques to extend the photon energy coverage of a self-seeding FEL. The proposed scheme utilizes a baseline configuration of a self-seeding FEL and does not require the installation of any additional hardware in the undulator system. The proposed technique can be easily implemented at already existing or planned x-ray FEL facilities to generate x-ray radiation pulses with consecutively tuning wavelength from soft x-ray to hard x-ray regions. Theory and simulation is carried out in this paper. The proposed scheme will be a reliable method to extend the wavelength range of the soft x-ray self-seeding scheme.  
Preparation for the Two-Color FEL Experiment at SXFEL  
  • W.Y. Zhang, C. Feng, B. Liu, Z. Qi
    SINAP, Shanghai, People's Republic of China
  Generation of double ultra-short radiation pulses with different carrier wavelengths in the x-ray regime is of remarkable interest in the FEL user community. Applications exist over a broad range of wavelengths involving pump-probe experiments. This paper presents the design studies for the two-color FEL experiment at the Shanghai soft x-ray FEL test facility. An optical system has been built to produce the double pulse two-color seed laser. We show the design and measurement results of this seed laser system.  
Design of the Beam Distribution System for a Soft X-Ray FEL User Facility in Shanghai  
  • S. Chen, H.X. Deng, C. Feng, B. Liu, D. Wang
    SINAP, Shanghai, People's Republic of China
  A soft X-ray user facility will be upgraded from an existing soft X-ray test facility in Shanghai. One or more extended FEL undulator lines will be constructed parallel to the previous undulator line. For simultaneous operation of several undulator lines, a beam distribution system is required for spreading the electron bunches from linac to each undulator lines. In this work, the physics design of such a beam distribution system will be described.  
A Novel Way to Generate Ultrafast X-ray Free Electron Laser Pulses  
  • D. Huang, C. Feng, Q. Gu
    SINAP, Shanghai, People's Republic of China
  Recently, ultrafast X-ray free electron laser (XFEL) pulses have become a key tool in many fields of scientific research. In this paper, a novel method to generate ultrafast XFEL pulses based on the laser heater in a linear accelerator (linac) is proposed. Contrary to other proposed methods, this new method is merely parasitic in the laser heater operation. Thus, it has significant advantages over the others such as being non-destructive, simpler, less expensive, etc.  
Three-Dimensional Manipulation of the Electron Beam Phase Space for Generating Intense Coherent Radiation in Storage Rings  
  • C. Feng, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
  Several methods have been developed in the last decade to improve the temporal properties of a storage ring based light source. Most of these methods employ external lasers to manipulate the longitudinal phase space of the electron beam to precisely tailor the properties of the radiation pulses. In this work, we show the possibility of the realization of generating fully coherent intense EUV and x-ray radiation pulses via three-dimensional manipulation of the electron beam phase space in storage rings. Theoretical analysis and numerical simulations show that this technique can be used for the generation of megawatt-scale level, fully-temporal coherent EUV and soft x-ray radiation pulses at a storage ring light source.