• S.C. Zhang, D.H. He, Q.K. Jia, Z. Jin, W. Li, S. Lu, L. Shang, B. Sun, Y. Wang, C. Yao, R. Zhuo
  USTC/NSRL, Hefei, Anhui

A photocathode injector system is developing at NSRL. A BNL type S-band photocathode RF gun has been built. The emittance will be compensated by a Solenoid. The driving laser is a high-Q product. It will be reformed into uniform distribution in the transverse distribution, but will not in the longitudinal direction. The whole system will be tested soon.

• Y.C. Xu, H. Hao, D.H. He, X.Q. Wang
  USTC/NSRL, Hefei, Anhui

Funding: Work supported by National Natural Science Foundation of China (No.10175062 & 10575100).

The light pulse interval adjustment at Hefei Light Source (HLS) can be realized by using pulsed orbit bump technique, which requires for high-frequency repetitive, high magnetic flux density, short pulse kicker magnet system of which the power supply modulator should be specially designed. The technique of solid state modulator based on MOSFET is being developed in National synchrotron Radiation Laboratory (NSRL). In this paper, the design of a prototype of solid-state modulator with 20 MOSFETs in parallel is introduced, including triggering system, drive circuit, transformer configuration. The oscillation induced by parasitic capacitance and inductance is discussed. This prototype with four stage adder can achieve 100ns width power pulse output with 112A, 2.4 kV to the kicker.

• Q. Luo, D.H. He, B. Sun
  USTC/NSRL, Hefei, Anhui

Funding: National “985 Project” （173123200402002); National Natural Science Foundation(10875117)

A new high brightness injector is planned to be installed at HLS, NSRL. It is based on a new photocathode RF electron gun. To steer the beam along the optimal trajectory, higher precision controlling of beam position is required. The positional resolution of the BPM system designed for the new RF gun should be higher than 10 μm. A new cavity BPM design is then given instead of old stripline one because of its higher positional resolution. In a normal symmetrical pill-box BPM design, machining tolerance will result in x-y coupling, which will cause cross-talk problem. A novel design is then presented here. To solve the problem before, a position cavity which has a racetrack cross section is used instead of a pill-box one. The ideal resolution of this design could be less than 3 nm.