Microwave measurements of the time evolution of electron density in the T-11M tokamak

Петров, В. Г.; Petrov, A. A.; Malyshev, A. Yu.; Markov, V. K.; Babarykin, A. V.

doi:10.1134/1.1648935

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…In recent years some measurements on tokamaks [2][3][4] have produced large polarimetric effects and it is expected [5] that this will occur even more in future tokamaks such as ITER. When polarimetry signals are large the Faraday and Cotton-Mouton effects do not combine linearly and it becomes difficult to obtain the pure Faraday and Cotton-Mouton effects from these signals.…”

Section: Introductionmentioning

confidence: 99%

Derivation of the pure Faraday and Cotton–Mouton effects when polarimetric effects in a tokamak are large

Segrè

Zanza

2006

Plasma Phys. Control. Fusion

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When polarimetric effects are large the Cotton-Mouton and Faraday effects do not combine linearly and it is not possible to separate exactly the pure Cotton-Mouton effect W 1 and the pure Faraday effect, W 3 . Four alternative approximate expressions for W 1 and W 3 in terms of measurable quantities are examined for tokamak configurations.Two of these approximations proposed recently are found to be preferable, some previous statements concerning them are corrected and the errors incurred by their use are evaluated.

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Section: Introductionmentioning

confidence: 99%

Derivation of the pure Faraday and Cotton–Mouton effects when polarimetric effects in a tokamak are large

Segrè

Zanza

2006

Plasma Phys. Control. Fusion

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“…The measurement of LID can be performed using a polarimeter [10,11,16,17] based on the Cotton-Mouton effect. It has the typical advantages of being free from phase jump errors and the influence of mechanical vibrations.…”

Section: Introductionmentioning

confidence: 99%

Line integrated density measurements on the Versatile Experiment Spherical Torus (VEST) using frequency sweep interferometer

Seo,

Wang,

Lee

et al. 2023

Plasma Phys. Control. Fusion

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A frequency sweep interferometer (FSI) operating in the frequency range of 50–75 GHz is installed in the versatile experiment spherical torus spherical tokamak to measure the line integrated density (LID). FSI measures the time derivative of phase to calculate the group delay, which is proportional to the LID under the condition that the microwave frequency is much higher than the plasma frequency. Since the group delay is calculated from the time derivative of phase and the frequency sweep rate, FSI is very sensitive to the measurement noise. In the view point of signal processing, derivative exaggerates the measurement noise. Therefore, sophisticated techniques for phase measurement and frequency linearization are required to obtain meaningful results with FSI. The detailed techniques and the hardware setup are explained in the paper. The LID measured by FSI is benchmarked with the LID measured by a conventional 94 GHz heterodyne interferometer. The two measurements agree well. A conventional interferometer can no longer provide LID when severe phase errors occur. This is because phase errors propagate to subsequent measurements. However, FSI provides LID during the entire discharge time successfully regardless of frequent measurement failure because the LID is obtained in FSI from the time derivative of phase rather than the phase. In this sense, FSI is suitable as a diagnostics for steady state plasmas. The main cause for the phase errors is identified as the beam path displacement due to the refraction of the plasma.

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Velocity Diagnosis of Critical Surface at Microwave Band in Laser-Induced Plasma

Wu¹,

Wang²,

Shunbo³

et al. 2008

Plasma Sci. Technol.

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Microwave measurements of the time evolution of electron density in the T-11M tokamak

Cited by 3 publications

References 3 publications

Derivation of the pure Faraday and Cotton–Mouton effects when polarimetric effects in a tokamak are large

Derivation of the pure Faraday and Cotton–Mouton effects when polarimetric effects in a tokamak are large

Line integrated density measurements on the Versatile Experiment Spherical Torus (VEST) using frequency sweep interferometer

Velocity Diagnosis of Critical Surface at Microwave Band in Laser-Induced Plasma

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