Formation of an internal transport barrier and magnetohydrodynamic activity in experiments with the controlled density of rational magnetic surfaces in the T-10 Tokamak

Razumova, K. A.; Андреев, В. В.; Bel’bas, I. S.; Gorshkov, A. V.; Dnestrovskij, A. Yu.; Dyabilin, K. S.; Kislov, A. Ya.; Лысенко, С. Е.; Notkin, G.E.; Timchenko, N.N.; Chudnovskiy, A. N.; Shelukhin, D. A.

doi:10.1134/s1063780x13090079

Cited by 5 publications

(7 citation statements)

References 11 publications

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“…Для анализа характера турбулентного спектра и величины нижнего номера моды m 1 мы используем здесь, как хорошо проверенную в экспериментах на токамаках [9][10][11] гипотезу о механизме образования внутренних барьеров (ITB) в зонах без рациональных поверхностей с низкими значениями m и n (q = m/n), в так называемых «зазорах» (gap или Гэп), где для низких значений m нет рациональных поверхностей. Сравнивая измеренную экспериментально ширину барьера  ITB с расчётной величиной  gap , которая пропорциональна (m 1 dq/dr) -1 , мы находим нижнюю граничную моду m 1 .…”

Section: характеристики турбулентности ответственной за радиальный тunclassified

Transport Barriers and Self-Organization of Plasmas

Razumova¹,

Лысенко²,

Timchenko³

2016

PAST-TF

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На основе представлений о самоорганизации плазмы в токамаке предлагается метод анализа характеристик турбулентного механизма, ответственного за перенос тепла по радиусу. Показано, что тепловой поток переносится преимущественно низкими модами МГД-неустойчивости. Чем больше поток, создаваемый в результате искажений профиля давления внешними факторами, тем шире спектр мод и тем меньше номер моды нижней границы спектра. Обсуждается роль мод с низкими полоидальными номерами в процессе формирования транспортных барьеров. Предлагается нетрадиционное объяснение формирования режимов с улучшенным удержанием.

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Section: характеристики турбулентности ответственной за радиальный тunclassified

Transport Barriers and Self-Organization of Plasmas

Razumova¹,

Лысенко²,

Timchenko³

2016

PAST-TF

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“…The phenomenon of the formation of ITB zones with reduced thermal conductivity was noted in the early 1990s. It was shown in a number of experimental studies [16][17][18][19][20] that the ITB is formed near the main rational surfaces with low poloidal numbers m and toroidal numbers n; the safety factor q = m/n in zones without rational surfaces with low values of m. A region without rational surfaces for a sufficiently low value of m was called 'the gap'. The existence of such regions was described for the first time in [21].…”

Section: Internal Transport Barriermentioning

confidence: 99%

“…An experimental verification of this position once again confirms the correctness of our explanation of the mechanism of ITB formation. Such experiments were performed in the T-10 tokamak [19]. The internal barrier was generated in a given plasma region with q = 1.5 as a result of off-axis electron cyclotron resonance heating (ECRH) and a rapid current ramp-up with a rate dI/dt = 3 MA s −1 .…”

Section: Experiments On the Formation Of The Barrier And The Islands ...mentioning

confidence: 99%

Physical processes determining plasma confinement in tokamaks with transport barriers from the point of view of self-organization

Razumova¹,

Андреев²,

Eliseev³

et al. 2021

Plasma Phys. Control. Fusion

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The goal of this article is to describe processes linked to energy confinement in tokamak plasmas from the perspective of self-organization—the main process that determines the behavior of turbulent plasmas. In the paper Razumova et al 2020 Plasma Phys. Rep. 46 337, such an analysis was performed for regimes without transport barriers. The present paper extends this approach to regimes with barriers and magnetic islands. In a shorter version, it was presented in Razumova et al 2020 Entropy 22 53, which showed that the appearance of islands in the inner part of the barrier is directly related to the formation of the barrier and limits its growth. We discuss the structure of the radial heat flux that carries energy from the plasma in such a way that the pressure profile remains close to the self-consistent profile (as observed in the experiment).

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“…This means that when we increase Γ, the lower mode in the turbulent spectrum can get into the Gap near some rational surface, and if the derivative dq/dr is sufficiently low, it leads to the formation of a barrier. Taking into account that for ITB formation we need to organize a wide Gap, we performed experiments, in which the ITB was generated in a given place with a given q [24]. The barrier near the surface with q = 3/2 was generated using off-axis ECR heating and a rapidly increasing plasma current.…”

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

“…Taking into account that for ITB formation we need to organize a wide Gap, we performed experiments, in which the ITB was generated in a given place with a given q [24]. The barrier near the surface with q = 3/2 was generated using off-axis ECR heating and a rapidly increasing plasma current.…”

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

Explanation of Experimentally Observed Phenomena in Hot Tokamak Plasmas from the Nonequilibrium Thermodynamics Position

Razumova

Андреев

Kasyanova

et al. 2019

Entropy

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In studying the hot plasma behavior in tokamak devices, the classical approach for collisional processes is traditionally used. This approach leaves unexplained a number of phenomena observed in experiments related to plasma energy confinement. Further, it is well known that tokamak plasma is always turbulent and self-organized. In the present paper, we show that the nonequilibrium thermodynamics approach allows us to explain many observed dependences and paradoxes; for example, puffing of impurities results in confinement improvement if zones of plasma cooling by impurities and additional plasma heating are not overlapped. The analysis of the experimental results shows the important role of radiation losses at the plasma edge in the processes determining its total energy confinement. It is shown that the generally accepted dependence of energy confinement on plasma density is not quite adequate because it is a consequence of dependence on radiation losses. The phenomenon of the appearance of internal transport barriers and magnetic islands can also be explained by plasma self-organization. The obtained results may be taken into account when calculating the operation of a future tokamak reactor.

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Formation of an internal transport barrier and magnetohydrodynamic activity in experiments with the controlled density of rational magnetic surfaces in the T-10 Tokamak

Cited by 5 publications

References 11 publications

Transport Barriers and Self-Organization of Plasmas

Transport Barriers and Self-Organization of Plasmas

Physical processes determining plasma confinement in tokamaks with transport barriers from the point of view of self-organization

Explanation of Experimentally Observed Phenomena in Hot Tokamak Plasmas from the Nonequilibrium Thermodynamics Position

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