Zhao, K.
(Kui Zhao)

THBOS04 The Present Applications of IR FEL at Peking University
Limin Yang, Jia'er Chen, Kui Zhao (PKU/IHIP, Beijing), MingKai Wang (Chinese Academy of Sciences, Beijing), Yunlan Su, Jinguang Wu, Yizhuang Xu (College of Chemistry and Molecular Engineering, Beijing)

In this study the sections of human tissues were treated under 9.5 μm FEL in the BFEL based on the vibrational spectroscopic investigation that significant differences occur between normal and malignant tissues. Under the defocus condition, the burning of tissue section at some part while other part remains unchanged, suggesting that the FEL can selectively destroy some part of tissue. Vibrational spectroscopic and microscopic methods have shown that the FEL can induce decomposition of malignant tissues. The application of FEL whose wavelength is on the characteristic bands of malignant tissues may provide a new method to kill cancer cells with higher selectivity. For understanding the interactions between FEL and biological tissues, structure changes of substances under irradiation by FEL of 9.414 μm and 6.228 μm were measured using FTIR spectroscopy. The samples include ATP, ADP, AMP, and D-ribose, etc. The FTIR spectra of the molecules before and after irradiation of FEL indicate molecular structure variations of the samples after irradiation of FEL, especially the rearrangement of their hydrogen bond networks, which may be caused by multiple photons process induced by FEL.

TUPOS33 Study on the Planar Undulator Scheme with Focusing Properties for PKU-FEL
Yuantao Ding, Jia'er Chen, Senlin Huang, Yugang Wang, Kui Zhao, Jiejia Zhuang (PKU/IHIP, Beijing)

An IR range SASE FEL test facility will be built at Peking University. The project is designed to get the SASE FEL at 7 micron driven by a superconducting accelerator. A hybrid planar Nd-Fe-B undulator is employed and the optimization of the external focus system for the undulator is studied. In the PKU-FEL facility, the electron energy is about 30-40 MeV. The combined function undulator with FODO lattice imposes quite stringent tolerances on the strength of the quads. To solve this problem, the weak natural focusing of the undulator in the vertical plane together with horizontally focusing quads, is proposed to supply the focusing in the facility. The combined function undulator of FOFO lattice and FF lattice in the horizontal plane are studied. Compared with the FODO lattice, the FOFO and FF lattice make the saturation a bit longer and the requirements of the field accuracy for the focusing system are much reduced.

TUPOS34 Beam Loading Tests on DC-SC Photoinjector at Peking University
Senlin Huang, Jia'er Chen, Xiangqiang Chu, Yuantao Ding, Jiankui Hao, Fei Jiao, Lin Lin, Xiangyang Lu, Shengwen Quan, Guimei Wang, Lifang Wang, Rong Xiang, Binping Xiao, Datao Xie, Limin Yang, Baocheng Zhang, Kui Zhao, Feng Zhu (PKU/IHIP, Beijing)

Since the beginning of commissioning in February 2003, lots of tests on the DC-SC photoinjector test facility have been performed. At present, Q0 of the 1+1/2-cell cavity has reached ~1E8 (at 4.2K) and the average gradient was about 4MeV/m. The DC photogun can provide stable electron beams. When the power of output laser went up to 100mW (266nm), the average beam current reached 400μA. Beam loading tests have been carried out, and SC acceleration was achieved. Average current of electron beams is about 100μA after acceleration.Further investigations are in progress to improve diagnostics system and to measure the emittance, energy spread and pulse length of electron beams.

TUPOS35 The Drive Laser System for DC-SC Injector
Xiangyang Lu, Lin Lin, Shengwen Quan, Fang Wang, Kui Zhao (PKU/IHIP, Beijing)

PKU-SCAF has developed a photoinjector which adopt a 1+1/2 cell super conducting cavity and DC electron gun. We also developed a low cost drive laser system for the photocathode DC gun to provide high average beam current. This laser system include a commercial high repetition rate, ps, all solid-state laser, the home made SHG and FHG, Fourier relay optics and the uniform illumination optics. The test results shows the output power at 266 nm of the laser system is more than 1.2W and got more than 500 A beam current from CsTe cathode from the DC gun.