Development of signal analysis method for the motional Stark effect diagnostic on EAST

Fu, Jia; Lyu, Bo; Liu, Haiqing; Li, Yingying; Liu, Dongmei; Wei, Yongqing; Fan, Chao; Shi, Yuejiang; Wu, Zhenwei; Wan, Baonian

doi:10.1088/2058-6272/aa7941

Cited by 4 publications

(1 citation statement)

References 13 publications

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“…To fully reconstruct the internal q profile self-consistently, kinetic measurement constraints must be used in conjunction with the internal q profile constraints [5]. In many tokamaks, the Motion Stark Effect (MSE) measurement is used to constrain the pitch angle of the magnetic field to reconstruct the q profile [8,9]. MSE is now being developed on EAST tokamak [10].…”

Section: Introduction and Overviewmentioning

confidence: 99%

Kinetic equilibrium reconstruction with internal safety factor profile constraints on EAST tokamak

FAN 樊,

LI 李,

QIAN 钱

et al. 2024

Plasma Sci. Technol.

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Reconstruction of plasma equilibrium plays an important role in the analysis and simulation of plasma experiments. The kinetic equilibrium reconstruction with pressure and edge current constraints has been employed on EAST tokamak. However, the internal safety factor (q) profile is not accurate. This paper proposes a new way of incorporating q profile constraints into kinetic equilibrium reconstruction. The q profile is yielded from the Polarimeter Interferometer (POINT) reconstruction. Virtual probes containing information on q profile constraints are added to inputs of the kinetic equilibrium reconstruction program to obtain the final equilibrium. The new equilibrium produces a more accurate internal q profile. This improved method would help analyze EAST experiments.

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Section: Introduction and Overviewmentioning

confidence: 99%

Kinetic equilibrium reconstruction with internal safety factor profile constraints on EAST tokamak

FAN 樊,

LI 李,

QIAN 钱

et al. 2024

Plasma Sci. Technol.

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Four-dimensional calibration turntable of the motional Stark effect diagnostic on EAST

Huang

Liu

et al. 2018

Review of Scientific Instruments

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The motional Stark effect (MSE) diagnostic is applied to measure the safety factor q and current density profile of a tokamak device, which are important parameters in realizing the high-performance and long-pulse steady state of a tokamak. A single-channel MSE diagnostic based on dual photoelastic modulators, whose sightline meets with the neutral beam injection at a major radius of R = 2.12 m, has been built for the D window of the Experimental Advanced Superconducting Tokamak (EAST). According to the requirements of MSE diagnostic polarimetric calibration, a high-precision four-dimensional calibration turntable, driven by four stepping motors and controlled by software running on the computer, was designed for EAST. The turntable allows us to rapidly calibrate the MSE diagnostic in a series of positions and angles during EAST maintenance. The turntable can move in four dimensions of translation, yaw, pitch, and roll of the polarizer and can create linearly polarized light at any given angle with accuracy of ∼0.05° for the MSE system offline calibration. The experimental results of the MSE diagnostic calibration in the laboratory show that the turntable has the advantages of high positioning accuracy, flexible spatial movement, and convenient control and fully meets the calibration requirements of an MSE diagnosis system.

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Real-time signal processing system based on FPGA for motional Stark effect diagnostic on EAST

Liu

Yang

et al. 2021

Review of Scientific Instruments

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The plasma current density profile plays a key role in the development of a high poloidal beta scenario, which is essential for long-pulse and high-performance plasma operation on a tokamak. Based on the polarimetry technique, a Motional Stark Effect (MSE) diagnostic has been built on the Experimental Advanced Superconducting Tokamak. To be prepared for real-time (RT) feedback control of the plasma current density profile in the future, a RT signal processing system has been developed. The RT signal processing system is composed of three functional modules: analog-to-digital conversion (ADC) module, polarization information extraction module, and digital-to-analog conversion (DAC) module. The final objective of this system is to acquire the polarization information of the MSE. Based on the field-programmable gate array unit, fast Fourier transformation is adopted to process the Photoelastic Modulator (PEM) digital signal, which was converted from a PEM signal via the ADC module. By means of frequency spectrum separation, the components around double modulating frequencies are restored through inverse fast Fourier transformation. Furthermore, the two amplitudes of their corresponding components can be obtained through a digital harmonic analyzer technique. Afterward, the ratio of the two amplitudes is calculated by arc tangent so that the polarization angle is obtained. Finally, the information of this polarization angle is converted into a voltage signal by the DAC module and then output in RT. The test results based on the RT signal processing system are in good agreement with those based on the phase lock-in amplifiers. The working cycle of this system is shorter than 10 ms, which meets the requirements of the MSE diagnostic as a RT controller. The algorithm of RT signal processing and the relevant technology applied for building this system are presented in the main body of this paper in detail.

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Development of signal analysis method for the motional Stark effect diagnostic on EAST

Cited by 4 publications

References 13 publications

Kinetic equilibrium reconstruction with internal safety factor profile constraints on EAST tokamak

Kinetic equilibrium reconstruction with internal safety factor profile constraints on EAST tokamak

Four-dimensional calibration turntable of the motional Stark effect diagnostic on EAST

Real-time signal processing system based on FPGA for motional Stark effect diagnostic on EAST

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