Mechanisms governing radial heat fluxes in tokamak plasma

Razumova, K. A.; Timchenko, N.N.; Dnestrovskij, A. Yu.; Лысенко, С. Е.

doi:10.1134/s1063780x16090087

Cited by 6 publications

(13 citation statements)

References 27 publications

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“…The safety factor q characterizes a helicity of magnetic field lines, / q m n = . This result was found in experiments on many tokamaks: TCV [17], T-10 [18][19][20], and JET [21][22][23].…”

Section: Internal Transport Barriers (Itbs)supporting

confidence: 63%

“…Using Relation 7and comparing the calculated Gap width with the barrier width for the large number of published results for different tokamaks, it was possible to find a rough dependence linking the radial dependence of the heat flux density with m1. The result is shown in Figure 10 [20]. Despite the roughness of such an estimate (we do not know the radial correlation length of a given mode), the points obtained at a variety of tokamaks were well grouped on a steep dependence: m1 should decrease with increasing the flux density Γ, that is,…”

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 96%

“…Inside this Gap, surfaces with m > m1 up to infinity exist, but there are no surfaces with m < m1. Simple analysis [20] shows that the radial width of the Gap is Determination of (χ 0 + χ 1 ) is more complicated. The value of…”

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

“…Inside this Gap, surfaces with m > m 1 up to infinity exist, but there are no surfaces with m < m 1 . Simple analysis [20] shows that the radial width of the Gap is Figure 9 shows the result of the rational surface density calculation for the MAST tokamak (low aspect ratio R/a = 1.5). We can see the electron temperature profile with ITB at q = 1 and rational surface density for two m 1 values: m 1 = 20 and m 1 = 30.…”

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

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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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“…The safety factor q characterizes a helicity of magnetic field lines, / q m n = . This result was found in experiments on many tokamaks: TCV [17], T-10 [18][19][20], and JET [21][22][23].…”

Section: Internal Transport Barriers (Itbs)supporting

confidence: 63%

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 96%

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

Section: Internal Transport Barriers (Itbs)mentioning

confidence: 99%

See 2 more Smart Citations

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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“…The fact that the ITB is formed in gaps indicates the connection of turbulent structures that transfer heat along the radius with RMSs. In [23], the spectrum of poloidal turbulence modes was analyzed for its dependence on the value of the heat flux density Γ transferred along the radius. We can estimate the lower boundary mode m 1 in the turbulent spectrum transferring the heat flux by comparing the experimentally measured barrier width of the ITB with the calculated gap width [23]:…”

Section: Internal Transport Barriermentioning

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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Features of self-organized plasma physics in tokamaks

Razumova¹

2017

Plasma Phys. Control. Fusion

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The history of investigations the role of self-organization processes in tokamak plasma confinement is presented. It was experimentally shown that the normalized pressure profile is the same for different tokamaks. Instead of the conventional Fick equation, where the thermal flux is proportional to a pressure gradient, processes in the plasma are well described by the Dyabilanin's energy balance equation, in which the heat flux is proportional to the difference of normalized gradients for self-consistent and real pressure profiles. The transport coefficient depends on the values of heat flux, which compensates distortion of the pressure profile with external impacts. Radiative cooling of the plasma edge decreases the heat flux and improves the confinement.

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Mechanisms governing radial heat fluxes in tokamak plasma

Cited by 6 publications

References 27 publications

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

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

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

Features of self-organized plasma physics in tokamaks

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