The Implementation of Real-Time Plasma Electron Density Calculation Based on FPGA for Tokamak Devices

Shu, Shuangbao; Lai, Jiancheng; Zhang, Yang; Chen, Meixia; Zhang, Yuzhong; Wang, Yong; Liu, Chengyue; Tao, Xiaojie

doi:10.1007/s10894-021-00305-5

Cited by 2 publications

(1 citation statement)

References 19 publications

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“…Compared with the zero-crossing comparison method, FFT method has a certain ability to suppress the influence of noise interference and amplitude modulation [5,17]- [23], but it cannot avoid the problem of initial phase error caused by asynchronous sampling of the signal to be measured. Using the interferometer to diagnose the plasma, the detected signal will appear amplitude modulation and frequency offset caused by phase offset (the starting phase of the local detected signal is 160 • , and the ending phase of the local measured signal is −43 • ), as shown in figure 1.…”

Section: Jinst 17 P06036mentioning

confidence: 99%

A phase processor used in terahertz interferometer for tokamak

Shi

Yang

et al. 2022

J. Inst.

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The commonly used phase processing techniques include coherence method, zero-crossing comparison method and FFT method. Due to the influence of noise, amplitude modulation and frequency modulation, these phase processing methods are easy to cause errors, thus affecting the measurement accuracy. In this paper, a phase processor based on all-phase fast Fourier transform is developed. The principle of the phase processing algorithm is analyzed, and the implementation process of the algorithm on FPGA is described. The effectiveness of the method is tested under different conditions. The experimental results show that the standard deviation of phase processing is 0.387° when the signal is sampled simultaneously under 90% AM modulation. When asynchronous sampling and 50% FM, the phase processing error is 0.371°. This phase processer has been used to the terahertz interferometer of the HL-2M device, the phase change of the output signal of the interferometer can be accurately processed when the plasma density changes dramatically, and the loss of phase processing information can be effectively avoided in the plasma diagnosis process. Based on the technical research proposed in this paper, a more accurate phase processing reference scheme is provided for plasma diagnosis of interferometer.

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Section: Jinst 17 P06036mentioning

confidence: 99%

A phase processor used in terahertz interferometer for tokamak

Shi

Yang

et al. 2022

J. Inst.

View full text Add to dashboard Cite

show abstract

High precision phase difference calculation based on adaptive mixed-radix All-phase FFT for Tokamak plasma electron density measurement

Shu,

Lai,

Wang

et al. 2024

J. Inst.

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In many Tokamak devices, laser interferometers, such as HCN, DCN, CO2, etc, are employed to measure the plasma electron density by calculating the phase difference between the reference signal and the detector signal. This paper proposes an adaptive All-phase fast Fourier transform (Ap-FFT) method in the electronic density of the plasma. And analyze the reasons why the multi-frequency measurement phase is inaccurate. The proposed method can reduce the accuracy of phase calculation by adjusting the conversion length and mixed-radix to reduce the spectrum leakage and grid effect. At the same time, the experimental data verifies the correctness of the calculation results of this method, and it shows that the measurement uncertainty of the method is 10% higher than the 1024-point Ap-FFT, and 15% higher than the 1024-point FFT. This method can be effectively applied to the measurement of the electronic density of an ionic plasma for plasma and provides a valuable reference for other phase detection systems and equipment.

show abstract

The Implementation of Real-Time Plasma Electron Density Calculation Based on FPGA for Tokamak Devices

Cited by 2 publications

References 19 publications

A phase processor used in terahertz interferometer for tokamak

A phase processor used in terahertz interferometer for tokamak

High precision phase difference calculation based on adaptive mixed-radix All-phase FFT for Tokamak plasma electron density measurement

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