[en] The admittance equivalence is structured to analyze the beam-cavity interaction. Compared to the traditional process based on impedance plane, the admittance method is concise, and the expressions are obtained with intuitive physical quantity. By use of these expressions, the injecting transient effect under heavy beam loading, such as the case of HLS is discussed. (authors)

[en] Some numerical research results for X-band disk-loaded waveguide accelerating structure at National Synchrotron Radiation Laboratory are described. A 9.37 GHz X-band travelling wave accelerating structures is designed, and dependent relationship between geometrical factors of the structure and RF parameters are studied. Some model cavities are made, and experimental studies are carried out by network analyzer HP8722D. These results provide a beneficial data for design and manufacture of X-band travelling wave accelerating structure

[en] By using the computer image processing technology and RF phase auto-shifting system, the ESS (Energy Stabilization System) was applied to 200 MeV Linac. the ESS adjusts beam energy automatically in a range of +-4 MeV. After adjustment beam energy stability is improved to +-6%

[en] A travelling wave reaonant-ring was constructed for RF window high power test of NSRL 200 MeV linac. The principle of the resonant-ring was described. A power gain of 4.5 and a peak power of 60 MW were achieved in the ring. The power test method and procedure were given out, and the electron multiple effect was discussed. The RF window passed test under the conditions of a peak power of 30 MW, an average power of 3.7 kW and a pulse length of 2.5 μs. (authors)

[en] The Experiment of RF modulation at the HLS (Hefei Light Source) is introduced. The 4%-8% AM (Amplitude Modulation) or the 2 degree - 3 degree PM (Phase Modulation) with the modulated frequency closed to the longitudinal synchrotron oscillation frequency improves the beam lifetime. The experiment also finds out the intensity of the beam spectrum reduced after applying the RF modulation, which shows that the modulation is useful for suppressing the coupled-bunch instability. (authors)

[en] Several RF cavities used in HLS storage ring are reviewed. A new structure for the cavity is proposed considering the high stability requirement in the intense beam-current mode. The dimension, design parameters and the HOM characteristics for the new cavity are presented, and a comparison of performance with the existing one is made

[en] A new RFKO (RF Knock Out) system for partial filling operation is in commission at the Hefei light source storage ring. This system is composed of a frequency divider, waveform generator, and vector signal source and wideband amplifier. The in-phase signal of beam bunch is obtained by dividing the reference signal from the storage ring's RF system. Triggered by the in-phase signal, the waveform generator outputs a pulse burst. Modulated by the pulse, the waveform generator produces the RFKO signal, and the RFKO signal is applied to the strip line after amplification. The single bunch operation is achieved in this way and the current has reached 18 mA at present. Some bunch-train patterns such as 3-train with 6-bunch and non-uniform bunch train are also tested. (authors)

[en] To build the set-up for energy calibration of electron beam by the method of resonant depolarization in HLS, physics calculation is finished, and the beam loss monitor system to measure the relative change of Touscheck lifetime made. With this system, the beam loss of Touscheck lifetime is measured. The change of Touscheck lifetime is expected to be measured due to depolarization. (authors)

[en] An experimental device was recently constructed for testing the beam characteristics of a compact self-bunching RF gun at the National Synchrotron Radiation Laboratory. It designs an independent monitor and control system for the experimental device so as not to disturb the operation of 200MeV LINAC. According to the three-level architecture of a general control scheme, the proposed system consists of circuits that execute kernel control, photosignal emission/reception, and switch values input/output, respectively. It performs timing control, device status monitoring as well as interlock protection, and it can be remotely operated with the assistance of PC software. Testing results show that our system achieves the specified performance and meets the requirement of experimental device stably and reliably. Our proposed system can also be applied to control other small-scale accelerators. (authors)

[en] In this paper, we present the design and optimization of a side-coupled accelerating structure with an energy switch. The beam parameters are optimized, and the electric field asymmetry in the first cell is analyzed. The new structure we designed has an improvement of 10 times in the accelerating field symmetry. Thermo-mechanical analysis is performed based on the electromagnetic results. The highest temperature is 72.5 ℃ at the nose cone, and the maximal deformation is 73 μm at the outer edge of the coupling cavity. (authors)