SXFEL装置上速调管输入输出特性曲线的线性化

doi:10.11889/j.0253-3219.2017.hjs.40.060102

Nuclear Techniques ›› 2017, Vol. 40 ›› Issue (6): 60102-060102.doi: 10.11889/j.0253-3219.2017.hjs.40.060102

• SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS • Previous Articles Next Articles

Linearization of the input and output characteristic curve of a klystron for SXFEL

SUN Sisi^1,2, ZHANG Junqiang¹, LI Lin¹, LIU Yajuan¹, GU Qiang¹, HUANG Dazhang¹, ZHAO Minghua¹

1 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Jiading Campus, Shanghai 201800, China;
2 University of Chinese Academy of Sciences, Beijing 100049, China

Received:2017-01-23 Revised:2017-03-21 Online:2017-06-10 Published:2017-06-06
About author:10.11889/j.0253-3219.2017.hjs.40.060102
Supported by:
Supported by National Natural Science Foundation of China (No.11675248)

Abstract

Abstract: Background: The output signal of klystrons for the soft X-ray free-electron laser (SXFEL) is processed by the low level radio frequency (LLRF) measurement and control system to ensure the stable operation of the amplitude and phase of the electric field of an radio frequency (RF) structure in the linear accelerator (LINAC). However, the nonlinearity of the input-to-output characteristic curve of the klystron makes the radio frequency regulation of the LLRF control system inefficient. Purpose: The study aims to design an online system to compensate the nonlinearity characteristic from klystrons in SXFEL. Methods: The online system uses the FPGA-based digital predistortion method, including three algorithms:third order polynomial, direct lookup table, and lookup table with linear interpolation. Results: In the on line experiment, the input-to-output characteristic curve of the klystron is linearized, and the system effectively compensates the nonlinearity characteristic introduced by the klystron. Conclusion: The online system improves the precision and accuracy of the LLRF control system, which meets the requirements of the SXFEL.

Key words: Klystron, Linearization, SXFEL

CLC Number:

TL53

SUN Sisi, ZHANG Junqiang, LI Lin, LIU Yajuan, GU Qiang, HUANG Dazhang, ZHAO Minghua. Linearization of the input and output characteristic curve of a klystron for SXFEL[J].Nuclear Techniques, 2017, 40(6): 60102-060102.

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Linearization of the input and output characteristic curve of a klystron for SXFEL

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