Hefei Light Source Research Articles

New Ceramic Chambers for the HLS Storage Ring

The new injection bump system of Hefei light source (HLS) storage ring is firstly introduced. The new system set a strict error limit to the rise time delay of the pulsed magnetic field, which is caused by the coating of the ceramic chamber. The error allowance is studied and the results are summarized. A new method of coating ceramic chambers was developed. The method, which employs Mo metallization techniques, is quite different from existing methods. Important issues of coating these chambers are presented. A unique, two-coil pulsed magnetic field measurement system was set up. Rise time delay of the pulsed field at different positions inside the ceramic chambers was measured. The rise time deviations inside a pair of chambers proved to be within the range of /spl plusmn/4 ns. A vacuum pressure of 2/spl times/10/sup -8/ Pa of the ceramic chambers was obtained after the installation in the storage ring. The chambers performed well. An average injection rate of 2-6 mA/s was obtained.

Application of frequency domain technique in HLS

The paper introduce the measurement of some beam parameters for Hefei Light Source (HLS) by frequency domain technique, which include the betatron tune, average beta function, natural chromaticity, corrected chromaticity, and center frequency. Additionally, the measurement of the influence of DC clearing electrodes on the betatron tune shift is also described. Some measurement results are given. The measurement results are compared with the theoretical values and shown to be in good agreement.

Measurement of optics parameters for HLS

The paper introduce the measurement of some optics parameters at 800 MeV for Hefei Light Source (HLS), which include the betatron tune, momentum compaction factor, beta function, dispersion function, natural chromaticity, corrected chromaticity. The swept frequency excitation method was used to measure betatron tune. The beta function is given by the betatron tune shift with quadrupole strength. The dispersion function is inferred from the orbit change induced by a shift in the rf frequency. The natural chromaticity is obtained by detecting the variation of the betatron tune as a function of the main dipole field strength. The corrected chromaticity is given by the betatron tune shift with rf frequency. The measurement results are compared with the theoretical values and are shown to be in good agreement.

Ion-Induced Beam Instability in an Electron Storage Ring

In a small electron storage ring, such as the Hefei Light Source (HLS) ring, the newly generated ions, which can not escape from the beam potential and then are trapped from turn to turn, will lead to the beam instability. The ions created by the leading bunches can perturb the trailing bunches and also themselves during their subsequent passage, which will make the amplitude of beam oscillation be damped and anti-damped periodically. A computer simulation based on the strong-weak model shows a good agreement with our analytical model using the linear theory.

Effect of the RF cavity temperature on low-energy injection at HLS.

The resonant frequency shift caused by the temperature of the RF cavity at the Hefei Light Source has been measured and the results analysed. The effect of this frequency shift on low-energy injection with a low cavity voltage is discussed, and a new injection mode is proposed.

Monitoring the beam profile in HLS with synchrotron light

Abstract The beam profile monitor built for HLS (Hefei Light Source) is presented. The monitor is composed of an imaging optical system, a commercial CCD TV camera as a detector, an electronic circuit, and a computer to calculate the beam dimensions. This technique has the ability to get the emittance of HLS with the superior resolution, to monitor the beam orbit and beam instability as well.

The study of LIGA technique at NSRL

The activity of LIGA technique was started in the fall of 1993 at National Synchrotron Radiation Laboratory (NSRL), some primary results have been obtained. Micro gearwheels were produced by deep-etch lithography using Hefei light source. The largest diameter of gearwheel is 200 μm, the smallest one only 35 μm, both with thickness of 50 μm. The first metallic structure of nickel was fabricated recently. The mask used in experiments was made by ourselves, it is a composite of kapton membrane as a mask blank, and gold as an absorber.

Progresses of synchrotron radiation applications at the NSRL

The Hefei light source has been open to users all over the country since April 1 of last year. Five beamlines and corresponding experimental stations are under operation at present. Synchrotron radiation research includes photoelectron spectroscopy, optical spectroscopy, photochemistry, soft x-ray microscopy, and x-ray lithography. One hundred and twenty proposals have been approved and about 40 of them carried out. We report some results in this paper.