Predistortion model of klystron based on Field Programmable Gate Array (FPGA)

Xie Chunjie; Tang Leilei; Liang Yu; Feng Guangyao; Wang Lin; Zhou Zeran

doi:10.11884/HPLPB202234.210214

Volume 34 Issue 3

Jan. 2022

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Article Navigation > High Power Laser and Particle Beams > 2022 > 34(3): 031022

Xie Chunjie, Tang Leilei, Liang Yu, et al. Predistortion model of klystron based on Field Programmable Gate Array (FPGA)[J]. High Power Laser and Particle Beams, 2022, 34: 031022. doi: 10.11884/HPLPB202234.210214

Citation:

Xie Chunjie, Tang Leilei, Liang Yu, et al. Predistortion model of klystron based on Field Programmable Gate Array (FPGA)[J]. High Power Laser and Particle Beams, 2022, 34: 031022. doi: 10.11884/HPLPB202234.210214

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Predistortion model of klystron based on Field Programmable Gate Array (FPGA)

doi: 10.11884/HPLPB202234.210214

National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China

Received Date: 2021-05-31
Rev Recd Date: 2021-10-19

Available Online: 2021-10-14

Publish Date: 2022-01-13

Abstract

Abstract

Hefei Infrared Free Electron Laser (IR-FEL) is a free electron laser device operating in mid-infrared and far-infrared. To achieve its design targets, a low level radio frequency (LLRF) system is needed to monitor and control the amplitude and phase of the acceleration field in the accelerator cavity. However, the input-to-output nonlinear characteristic of the amplitude of the klystron decreases the control gain near the saturated region, which reduces the efficiency of feedback. In this paper, a predistortion algorithm based on FPGA is designed to correct the nonlinear characteristics of the amplitude of the klystron, and the 2048-node direct lookup-table algorithm and the 32-node lookup-table with linear interpolation algorithm are compared and tested online. The comparison shows that, in the condition of accuracy requirement, the direct lookup-table algorithm consumes 25% less clocks than the lookup-table with linear interpolation algorithm, with less total resource consumption. The feedback efficiency is compared on Toshiba E3729 klystron, and it is improved by 43% after adding the direct lookup-table algorithm based predistortion module.
- infrared free electron laser,
- linear accelerator,
- predistortion,
- klystron,
- low-level RF system,
- field programmable gate array

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References(10)

References

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