1. Development of prototype real-time Thomson scattering diagnostic in KSTAR.
- Author
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Lee, Jong-ha, Lee, Seung Ju, Kim, Ha Jin, Hahn, Sang Hee, Yamada, Ichihiro, and Funaba, H.
- Subjects
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THOMSON scattering , *FOURIER transforms , *ELECTRON temperature , *PLASMA confinement , *PLASMA diagnostics , *POLYCHROMATORS - Abstract
A prototype real-time (RT) Thomson scattering system was tested in a KSTAR Thomson scattering diagnostic system [1]. For this RT-Thomson system, 155 channels of 5 GS/s digitizer were operated (31 polychromators, each has 5 signal channels used in the KSTAR Thomson scattering system). The 5 Giga Sampling / second (GS/s) digitizer restored the pulsed Thomson scattering signals, and these acquired digital signals were fitted using a pulse function and Fast Fourier Transformation (FFT) method to remove noise with high speed on the TS signals [2]. The pulse fitting parameters (pulse height, rising time, falling time and peak position) were applied to calculate plasma parameters like the electron temperature (T e). To reduce the T e calculation time, a neural-network (NN) method was introduced using graphic processor unit (GPU) calculations. These plasma parameters were transmitted to the KSTAR plasma control system (PCS)using a reflective memory (RFM) card. The delay time of this RT-Thomson before transfer to the RFM card measured less than 7 ms for a T e calculation of 31 positions, and the transfer time from the RFM card to the PCS was 6.8 ms. Therefore, at 80.31% of KSTAR long pulse plasma shot # 32,763 (84.15 s), the end-to-end treatment time was less than 50 ms. The uniqueness of this paper is that it uses 5GS/s digitizer, Fast Fourier Transformation FFT fitting method, and neural- network (NN) analysis system, and finally succeeds in transferring Te profile data to the KSTAR PCS system in real- time (80.31% within 50 ms delay) using RFM cards for KSTAR long pulse plasma (84.15 s) for the first time. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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