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Zhang Z.,CAS Shanghai Institute of Applied Physics | Zhang Z.,University of Chinese Academy of Sciences | Zhang Z.,Shanghai Key Laboratory of Cryogenics & Superconducting RF Technology | Zhao Y.,CAS Shanghai Institute of Applied Physics | And 25 more authors.
He Jishu/Nuclear Techniques | Year: 2015

Background: In-phase/Quadrature (I/Q) demodulation technology is widely used in radio frequency signal phase control system. As the intrinsic errors in hardware, such as the imbalances of gain and phase in 90° hybrid and 0° hybrid, direct current (DC) offsets and phase errors from length difference of circuits, the output signal is an ellipse and the output phase is nonlinear to the input radio frequency (RF) signal. The detection of phase precision is influenced. Purpose: This study aims to reduce the effects of errors existed in the I/Q demodulators. Methods: A calibration method for I/Q demodulation technique is proposed and applied to research and development of I/Q integrate circuits, which is based on the surface mounted devices (SMD) chip. Results: Experimental tests showed that the phase error was less than ±0.15°, the amplitude stability was less than ±1%, and the channel delay was less than 10 ns. Conclusion: This calibration method, together with the designed circuit board for the RF signal front end preprocessing can reduce the effects of intrinsic errors efficiently. It has been being used in upgrading of beam trip diagnostic system in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF). ©, 2015, Science Press. All right reserved.


Yang J.,CAS Shanghai Institute of Applied Physics | Yang J.,University of Chinese Academy of Sciences | Yang J.,Shanghai Key Laboratory of Cryogenics & Superconducting RF Technology | Ma Z.,CAS Shanghai Institute of Applied Physics | And 15 more authors.
He Jishu/Nuclear Techniques | Year: 2015

Background: Energy Recovery Linacs (ERLs) are being developed over the world to realize future light sources and other applications. Purpose: The aim is to design a new 1500 MHz 5-cell superconducting cavity for main linac in the ERL. Methods: The new cavity geometry was optimized by several radio-frequency softwares. Results: The new cavity is endowed with the following advantages: with the R/Q of the fundamental mode TM010 to be 550 Ω, cryogenic losses could be reduced effectively; in order to reduce the risk of field emission, the parameters Epk/Eacc, Bpk/Eacc were optimized respectively to 2.06 and 4.22; a larger beam pipe was employed to propagate the higher order modes (HOMs) out of the cavity, increasing the damping efficiently for the dangerous HOMs. Conclusion: It was found that radio frequency property of the new cavity could meet the requirements of ERL-based Free Electron Laser (FEL) very well. ©, 2015, Science Press. All right reserved.

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