Preparations for the motional Stark effect diagnostic on EAST

Fu, Jia; Li, Y. Y.; Lyu, Bo; Peng, Sheng; Zhang, Y.; Yin, Xiufeng; Shi, Yuejiang; Yu, Yijun; Ye, M. Y.; Wan, Baonian

doi:10.1063/1.4893996

Cited by 11 publications

(7 citation statements)

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“…The q profiles inferred from the POINT measurement suggests a stationary and broad current profile observed in the H-mode phase, and this result is consistent with the reduction of plasma internal inductance, l i , observed during the L-H transition. Beyond this, a multi-channel motional Stark effect (MSE) diagnostic was also under development, to further expand the capability of measuring current density profiles [15].…”

Section: Upgrade and Achievement In Support Of Long-pulse Advanced Sc...mentioning

confidence: 99%

Overview of EAST experiments on the development of high-performance steady-state scenario

et al. 2017

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The EAST research program aims to demonstrate steady-state long-pulse advanced high-performance H-mode operations with ITER-like poloidal configuration and RF-dominated heating schemes. Since last IAEA FEC, EAST has been upgraded with all ITER-relevant auxiliary heating and current drive systems, enabling the investigation of plasma profile control by coupling/integration of various combinations. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and maintained at relatively high density, even up to n e ~ 4.5 × 10 19 m-3 , where a current drive effect is still observed. Significant progress has been achieved on EAST, including: i). Demonstration of a steady-state scenario (fully non-inductive with V loop ~ 0.0V at high β P ~ 1.8 and high performance (H 98,y2 > 1.0) in upper single-null (ε ~ 1.6) configuration with the tungsten divertor; ii) Discovery of a stationary ELM-stable H-mode regime with 4.6 GHz LHCD; iii) achievement of ELM suppression in slowly-rotating H-mode plasma with the application of n = 1 and 2 RMPs.

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Section: Upgrade and Achievement In Support Of Long-pulse Advanced Sc...mentioning

confidence: 99%

Overview of EAST experiments on the development of high-performance steady-state scenario

et al. 2017

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“…The study characterizes the constraints in the beam operation with the three ion sources to avoid the spectral overlap at the region of interest. Many of the mid-size tokamaks such as DIII-D and EAST are under the similar situations [24] and this work may provide a guideline on how to operate the multi-ion-source NBI making the MSE measurements. The spectral study has also assisted the determination of the bandpass filter design by identifying the MSE polarization component that is free from the interference by other polarization signals and the MSE emission from other ion sources.…”

Section: Discussionmentioning

confidence: 97%

Analysis of neutral hydrogenic emission spectra in a tokamak

Chung

Jaspers

2015

J. Inst.

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Balmer-α radiation by the excitation of thermal and fast neutral hydrogenic particles has been investigated in a magnetically confined fusion device, or tokamak, from the Korea Superconducting Tokamak Advanced Research (KSTAR). From the diagnostic point of view, the emission from thermal neutrals is associated with passive spectroscopy and that from energetic neutrals that are usually injected from the outside of the tokamak to the active spectroscopy. The passive spectroscopic measurement for the thermal Balmer-α emission from deuterium and hydrogen estimates the relative concentration of hydrogen in a deuterium-fueled plasma and therefore, makes a useful tool to monitor the vacuum wall condition. The ratio of hydrogen to deuterium obtained from this measurement qualitatively correlates with the energy confinement of the plasma. The Doppler-shifted Balmer-α components from the fast neutrals features the spectrum of the motional Stark effect (MSE) which is an essential principle for the measurement of the magnetic pitch angle profile. Characterization of this active MSE spectra, especially with multiple neutral beam lines crossing along the observation line of sight, has been done for the guideline of the multi-ion-source heating beam operation and for the optimization of the narrow bandpass filters that are required for the polarimeter-based MSE diagnostic system under construction at KSTAR.

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“…The basic modulation frequencies are 20/23 kHz, which are determined by the PEM size. One fast data acquisition system (1 MHz) is employed in the single channel MSE system on EAST [14]. Figure 1(a) shows the MSE original testing data recorded by the fast data acquisition system, figure 1(b) shows the frequency spectrum deduced by fast Fourier transformation.…”

Section: Experimental Analysesmentioning

confidence: 99%

“…The basic modulation frequencies are 20/23 kHz, which are determined by the PEM size. One fast data acquisition system (1 MHz) is employed in the single channel MSE system on EAST [14]. In order to demodulate one second harmonic amplitude such as 40 kHz by the DHA technique, the key step is to define two frequency windows around 40 kHz on the conjugate FFT results described by equation (14); here, a square shape is defined and shown in figure 2(a).…”

Section: Experimental Analysesmentioning

confidence: 99%

“…One fast data acquisition system (1 MHz) is employed in the single channel MSE system on EAST [14]. In order to demodulate one second harmonic amplitude such as 40 kHz by the DHA technique, the key step is to define two frequency windows around 40 kHz on the conjugate FFT results described by equation (14); here, a square shape is defined and shown in figure 2(a). The window width is 1.4 kHz and no other harmonic peaks are contained in this range.…”

Section: Experimental Analysesmentioning

confidence: 99%

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

Lyu

Liu

et al. 2017

Plasma Sci. Technol.

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A pilot single-channel Motional Stark Effect (MSE) diagnostic has been developed on EAST since 2015. The dual photo-elastic modulators (PEM) were employed to encode the polarization angle into a time-varying signal. The pitch angle was related to the ratio of modulation amplitude at the second harmonic frequency. A digital harmonic analyzer (DHA) technique was developed for extracting the second harmonic amplitude. The results were validated with a hardware phase lock-in amplifier, and is also consistent with the software dual phase-locking algorithm.

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Preparations for the motional Stark effect diagnostic on EAST

Cited by 11 publications

References 11 publications

Overview of EAST experiments on the development of high-performance steady-state scenario

Overview of EAST experiments on the development of high-performance steady-state scenario

Analysis of neutral hydrogenic emission spectra in a tokamak

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

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