Plasma density control in real-time on the COMPASS tokamak

Janky, F.; Hron, M.; Havlíček, J.; Varavin, M.; Žáček, F.; Seidl, J.; Pánek, R.

doi:10.1016/j.fusengdes.2015.04.065

Cited by 15 publications

(7 citation statements)

References 14 publications

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“…The performance of the piezo-electric valve is affected by the operating temperature and the stickiness of the valve [4,24,25]. The temperature of the piezo valve affects the throughput of the gas to be injected.…”

Section: Stickiness Of Piezo-electric Valvementioning

confidence: 99%

“…plasma current, average particle density [2][3][4][5], temperature and position has been a challenging task in recent years. Real-time electron density control [3,6] plays a crucial role in magnetically confined fusion machines which is affected by plasma confinement, the interaction of the plasma with the walls, conditioning of the wall, gas injection, and pumping [4]. One of the most significant factors is the gas injection, which is likely to be the most suitable actuator for density control in ADITYA-U.…”

Section: Introductionmentioning

confidence: 99%

“…COMPASS tokamak has a 2 mm interferometer system for density estimation and a proportional integral (PI) controller controls the amount of injected gas during the discharge [4]. In J-TEXT tokamak, hydrogen cyanide (HCN) laser interferometer measures electron density, and a proportional integral derivative (PID) based gas injection system controls the amount of gas introduce during plasma discharges [6].…”

Section: Introductionmentioning

confidence: 99%

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Real-time density feedback control in ADITYA-U Tokamak

et al. 2022

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A real-time density feedback control system with a 100 GHz heterodyne interferometer has been designed, developed, and commissioned in ADITYA-U tokamak. It consists of three subsystems i.e. density measurement, feedback control, and gas fuelling. A proportional feedback controller is configured in voltage amplitude mode to operate the piezo valve for gas injection. Experiments are performed during plasma discharges to achieve a predefined density evolution as well as constant density. Stickiness of the piezo valve restricts the temporal response of the valve. It is required to minimize during the plasma discharge for a fast density response which is achieved by a short preceding voltage pulse known as a stick pulse. This paper describes the implementation of a real-time density feedback control system which is successfully validated using another existing 140 GHz interferometer system in ADITYA-U. Moreover, the developed system consumes low power, is cost-effective and re-programmable, can be easily upgraded, and provides interlock with plasma parameters.

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Section: Stickiness Of Piezo-electric Valvementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Real-time density feedback control in ADITYA-U Tokamak

et al. 2022

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“…Therefore, the phase response does not suffer from fringes for the full range of COMPASS densities, which is more than 12 × 10 19 m −3 . Both the real-time and post-processed electron density signals are corrected to a real plasma shape and to a non-linearity of the refractive index of the plasma at high densities [37]. Obtained results allow precise phase measurements in the phase range of 0-360 • with a fast reset possibility.…”

Section: Upgrade Of Optical and Microwave Diagnostics And Plasma Tomo...mentioning

confidence: 99%

Progress in diagnostics of the COMPASS tokamak

et al. 2017

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“…The measurement technology of electron density of magnetic confinement fusion plasma by interferometer has been used in many tokamak devices [1]- [5], such as HL-2M, HL-2A, EAST, etc. The output of the interferometer usually contains the signal passing through and not passing through the plasma, which is denoted as the detected signal and the reference signal respectively (D 𝑠 and R 𝑠 ).…”

Section: Introductionmentioning

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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Plasma density control in real-time on the COMPASS tokamak

Cited by 15 publications

References 14 publications

Real-time density feedback control in ADITYA-U Tokamak

Real-time density feedback control in ADITYA-U Tokamak

Progress in diagnostics of the COMPASS tokamak

A phase processor used in terahertz interferometer for tokamak

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