Correlation properties of Geodesic Acoustic Modes in the T-10 tokamak

Melnikov, A. V.; Eliseev, L.G.; Лысенко, С. Е.; Perfilov, S.V.; Shelukhin, D. A.; Vershkov, V.A.; Zenin, V.N.; Krupnik, L. I.; Kharchev, Ν. K.; Team, Hibp

doi:10.1088/1742-6596/591/1/012003

Cited by 16 publications

(15 citation statements)

References 9 publications

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“…The regimes with low magnetic fields allowing us to extend the HIBP observation area towards the plasma centre were studied in details. In these regimes HIBP was able to observe the area from the periphery (ρ = 0.7-1) to the centre (ρ = 0.25) and got the first indication of the radial constancy of the GAM frequency [10,11]. Following [21] we study first the regime (B t = 1.55 T, I p = 140 kA), which is characterized by the low line-averaged density, slowly evolving from ne = 1.3 × 10 19 to 2.4 × 10 19 m −3 due to the gas-puffing.…”

Section: Radial Structure Of Gammentioning

confidence: 93%

“…GAM amplitude evolution with density increase was first studied by HIBP at the plasma periphery [22]. In the present study the wide radial area was analysed for the first time.…”

Section: Gam Dependence On Densitymentioning

confidence: 94%

“…There are some experimental works showing the radial variation of the GAM frequency [7]. However, other experiments suggest that the observed GAM fluctuations have constant frequency over some radial extent, limited by diagnostic capabilities, and thus differ from (1) [8][9][10][11]. So, the GAM radial structure is an open question at the moment.…”

Section: Introductionmentioning

confidence: 98%

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The features of the global GAM in OH and ECRH plasmas in the T-10 tokamak

et al. 2015

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Zonal flows and their high-frequency counterpart, the geodesic acoustic modes (GAMs) are considered as a possible mechanism of the plasma turbulence self-regulation. In the T-10 tokamak GAMs have been studied by the heavy ion beam probing and multipin Langmuir probes. The wide range of the regimes with Ohmic, on-axis and off-axis electron cyclotron resonance heating (ECRH) were studied (B t = 1.5-2.4 T, I p = 140-300 kA, ne = (0.6-6.0) × 10 19 m −3 , P EC < 1.2 MW). It was shown that GAM has radially homogeneous structure and poloidal m = 0 for potential perturbations. The local theory predicts that f GAM ∼ √ T /m i /R, that means the frequency increases with the decrease of the minor radius. In contrast, the radial distribution of experimental frequency of the plasma potential and density oscillations, associated to GAM, is almost uniform over the whole plasma radius, suggesting the features of the nonlocal (global) eigenmodes. The GAM amplitude in the plasma potential also tends to be uniform along the radius. GAMs are more pronounced during ECRH, when the typical frequencies are seen in the narrow band from 22 to 27 kHz for the main peak and 25-30 kHz for the higher frequency satellite. GAM characteristics and the range of GAM existence are presented as functions of T e , density, magnetic field and P EC .

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Section: Radial Structure Of Gammentioning

confidence: 93%

“…GAM amplitude evolution with density increase was first studied by HIBP at the plasma periphery [22]. In the present study the wide radial area was analysed for the first time.…”

Section: Gam Dependence On Densitymentioning

confidence: 94%

Section: Introductionmentioning

confidence: 98%

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The features of the global GAM in OH and ECRH plasmas in the T-10 tokamak

et al. 2015

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“…It is basically a high frequency zonal flows [1,2,4,7] and normally confine within a small radial width. Also, recently it is found that it can be a global eigenmode as well which exhibits longrange spatial correlation [8] but not in all Tokamaks or Stellarators. So, it is necessary to detect experimentally the GAM mode collecting the information from approximately same magnetic field surfaces.…”

Section: Resultsmentioning

confidence: 99%

Development of an interactive code for quick data analyses between STOR-M tokamak experimental plasma discharges

Nakajima¹,

Basu²,

Melnikov³

et al. 2022

Preprint

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Saskatchewan Torus-Modified (STOR-M) is a small tokamak, well known for various fusion related basic experimental studies such as edge turbulent heating, different instabilities, AC (alternating current) tokamak operation, Ohmic H-mode triggering by the electrode biasing, fueling and momentum injection by Compact Torus(CT) injection, and effects of Resonance Magnetic Perturbations (RMP), among others. Some of those experiments require real time visualization of magnetic surface reconstructions either through EFIT or quick analyses and visualization of experimental data during experiments. Recently experimental studies of Geodesic Acoustic Mode(GAM) and zonal flows had been performed in STOR-M tokamak. The GAM experiments strongly require collection of fluctuations data from different Langmuir probes installed at different poloidal locations, but on the same magnetic surfaces. This is need of the adjustment of radial locations between discharges. It is therefore important to analyze and visualize the features of all probe data quickly during discharges. For this purpose, a Python code has been developed and used for quick analyze of data. This article will describe the development of the code using Python and its use in detail.

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“…На примере этого же импульса проиллюстрировано значение используемых далее понятий амплитуды и частоты ГАМ. Ранее было показано, что ГАМ имеет перемежаемую структуру [10,11] и состоит из стохастической последовательности отдельных вспышек. Поэтому её мгновенная амплитуда сильно меняется за время порядка 1 мс.…”

Section: схема экспериментаunclassified

Plasma Electric Potential and Geodesic Acoustic Mode Evolution in Ohmic and Ecrh Regimes With Pulsed Impurity Puffing on the T-10 Tokamak

Zenin¹,

Klyuchnikov²,

Melnikov³

et al. 2016

PAST-TF

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Эволюция электрического потенциала и геодезических акустических мод в омических и ЭЦР-режимах … ВАНТ. Сер. Термоядерный синтез, 2016, т. 39, вып. 3 91 Качественно сравниваются геодезические акустические моды (ГАМ) и эволюция среднего уровня электрического потенциала плазмы в токамаке Т-10 в режимах с импульсным (5 мс) напуском различных примесей (гелия, азота и неона). Показано, что напуск примеси меняет уровень потенциала. Также показано, что напуск примеси сильно влияет на ГАМ, резко снижая её амплитуду и снижая частоту. Это влияние продолжается в течение примерно 50 мс, затем амплитуда и частота ГАМ выходят на новый стационарный уровень. Приведены сравнения параметров ГАМ с основными плазменными параметрами и уровнем флуктуаций электронной плотности. Рассмотрена эволюция частоты ГАМ в сравнении с теоретически ожидаемой зависимостью для частоты локальных ГАМ с локальными значениями температуры на периферии.Ключевые слова: токамак, Т-10, ГАМ, зондирование плазмы пучком тяжёлых ионов.The geodesic acoustic mode (GAM) and the evolution of the average level of the electrostatic plasma potential in the T-10 tokamak in the regime with short (5 ms) impurity puffing are considered in this work. Plasma potential and GAM evolution are compared qualitatively at helium, nitrogen and neon impurities puffing. It was shown that impurity puffing changes the average plasma potential level. It was also shown that impurity puffing strongly affects GAM properties, reducing its amplitude sharply and decreasing its frequency. This effect lasts for about 50 ms, and then the amplitude and frequency of GAM reaches a new stationary level. The GAM parameters are compared with the evolution of the basic plasma parameters and the turbulence level of electron density. The GAM frequency evolution was considered versus theoretical dependence for local GAM taking into account peripheral temperatures.

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Correlation properties of Geodesic Acoustic Modes in the T-10 tokamak

Cited by 16 publications

References 9 publications

The features of the global GAM in OH and ECRH plasmas in the T-10 tokamak

The features of the global GAM in OH and ECRH plasmas in the T-10 tokamak

Development of an interactive code for quick data analyses between STOR-M tokamak experimental plasma discharges

Plasma Electric Potential and Geodesic Acoustic Mode Evolution in Ohmic and Ecrh Regimes With Pulsed Impurity Puffing on the T-10 Tokamak

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