Dynamics of the electron thermal diffusivity at improved energy confinement during lower hybrid plasma heating in the FT-2 tokamak

Kouprienko, D. V.; Altukhov, A. B.; Gurchenko, A. D.; Gusakov, E. Z.; Kantor, M. Yu.; Lashkul, S. I.; Esipov, L. A.

doi:10.1134/s1063780x10050016

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…The reference low-current FT-2 research tokamak (major radius R = 55 cm, minor radius a = 8 cm) hydrogen ohmic discharge (plasma current of 18.9 kA, magnetic field 2.3 T) possesses modest parameters determined by a set of tokamak diagnostics [4] among which several possess unique performance. The electron density measurements performed by multi-pass intra-cavity Thomson scattering (TS) [5] providing high temporal resolution and high accuracy and microwave interferometer resulted in profile shown in figure 1 possessing maximal density of 5 × 10 13 cm −3 .…”

Section: The Ft-2 Discharge and Diagnosticsmentioning

confidence: 99%

“…Large-scale mean E × B flows, meso-scale zonal flows and fine-scale micro-turbulence excited due to specific profiles of plasma parameters and leading to anomalous transport have been in the spotlight of experimental and theoretical research in magnetically confined plasmas for a long time [1,2]. In a recent brief communication [3], massively parallelized particle-in-cell simulations of the electron and ion gyrokinetic particle distribution function and the electric field were conducted for the small research FT-2 limiter tokamak [4] to study these phenomena and their complex interplay from first principles simulations, and quantitative comparisons were successfully presented with measurements, this being of importance, as all the above mentioned processes were first time simultaneously incorporated into one simulation. 0741-3335/13/124034+07$33.00 In the present paper, to illustrate highlights of such an approach following [3], results of the global gyrokinetic particle-in-cell simulations will be presented in more detail and quantitatively compared to experimental data characterizing the tokamak turbulent dynamics and transport phenomena at micro, macro and meso-scale.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anomalous transport and multi-scale drift turbulence dynamics in tokamak ohmic discharge as measured by high resolution diagnostics and modeled by full-fgyrokinetic code

Gusakov

Altukhov

Bulanin

et al. 2013

Plasma Phys. Control. Fusion

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The complex interaction between large-scale mean EB flows, meso-scale zonal flows and fine-scale micro-turbulence excited due to specific profiles of plasma parameters and leading to anomalous transport is an important area of experimental and theoretical research in magnetically confined plasmas. In this paper the global gyrokinetic full particle distribution particle-in-cell simulations performed for Ohmic discharge of small research FT-2 limiter tokamak are for the first time validated against experimental data obtained both with a set of standard tokamak diagnostics and by sophisticated microwave backscattering techniques characterizing the tokamak turbulent dynamics and transport phenomena at micro, macro and intermediate scales. As a result of the simulation carried out with the ELMFIRE code an overall reasonable agreement between the numerical expectations and the experimental estimations of the electron and ion effective heat conductivity profiles obtained from the primary experimental profiles is achieved. The agreement obtained at the macro-level was strengthen at the microlevel and for intermediate turbulent scales using the Doppler reflectometry (DR), radial correlation reflectometry (RCR) and Doppler Enhanced Scattering (ES) microwave diagnostics. The turbulence dynamics at the micro-scale measured by DR at FT-2 were compared to the ELMFIRE predictions using synthetic DR diagnostics. As a result, not only the experimental DR spectra frequency shift, but its width and even the shape of the spectra was well reproduced by synthetic diagnostic indicating comparable rotation and spreading of the selected turbulent density fluctuations. The turbulence radial correlation length dependence on its frequency provided by the modeling appears to be in reasonable agreement to that given by RCR. The fluctuation poloidal rotation velocity profile obtained by the DR is very close to that obtained from the synthesized DR spectrum and also close to that given by ES and to the value produced by ELMFIRE for plasma EB drift velocity. The large spectral width of the DR and ES spectra is explained by fast and strong variation of radial electric field observed in the modeling. Giant oscillations of the field at a frequency of approximately 30-50 kHz much smaller than the typical drift wave frequency, but much larger than the inverse energy confinement time, observed by DR and ES as well, are attributed to the geodesic acoustic mode (GAM). This attribution is supported by comparison of the oscillation frequency dependence on the radial position with analytical prediction for the GAM frequency accounting for the impurity contribution. The dispersion of radial electric field estimated from the ES is found to be comparable to the huge E r dispersion provided by the gyrokinetic modeling. Moreover the GAM correlation length and phase velocity determined using ES technique appears to be close to those obtained by the ELMFIRE. The interrelations of GAM and drift wave turbulence in experiment and gyrokinetic modeling are compared....

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Section: The Ft-2 Discharge and Diagnosticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anomalous transport and multi-scale drift turbulence dynamics in tokamak ohmic discharge as measured by high resolution diagnostics and modeled by full-fgyrokinetic code

Gusakov

Altukhov

Bulanin

et al. 2013

Plasma Phys. Control. Fusion

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“…The probing frequency range is not wide enough in small machines; moreover, the ratio of wave propagation region width to the vacuum wave length is small. For example, at the small FT-2 research tokamak it is given by L 0 f 0 /c ≈ 5.3 where the reference frequency is f 0 = 40.1 GHz and the reference frequency cut-off position is L 0 = 0.04 m. Nevertheless, according to experimental results [14] a rather steep plasma density profile in the FT-2 tokamak could be assumed linear that allows us to test the proposed reconstruction scheme in this tight geometry.…”

Section: Reconstruction Of the Turbulence Spectrum And Ccf For The Sm...mentioning

confidence: 98%

Numerical modeling of micro turbulence wave number spectra reconstruction using radial correlation reflectometry: I. O-mode reflectometry at the linear plasma density profile

Kosolapova¹,

Gusakov²,

Heuraux³

2012

Plasma Phys. Control. Fusion

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Based on the one-dimensional analytical theory of radial correlation reflectometry (RCR), numerical models of RCR experiments have been built. Computations are carried out for O-mode at a simple linear plasma density profile under conditions relevant to experiments. The turbulence spectrum and cross correlation function reconstruction procedure is applied and its feasibility is demonstrated while the assumptions of the model are fulfilled. The limitations of the method are discussed. The numerical models of the RCR experiments, targeted at the reconstruction of the turbulence spectrum in tokamaks where the plasma density profile can be approximated by a linear density profile, are performed and show in most of the cases that the wave number spectra can be extracted. The RCR capabilities and dependences on the main experimental parameters are also studied.

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Gyrokinetic full-torus simulations of ohmic tokamak plasmas in circular limiter configuration

Korpilo

Gurchenko

Gusakov

et al. 2016

Computer Physics Communications

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Dynamics of the electron thermal diffusivity at improved energy confinement during lower hybrid plasma heating in the FT-2 tokamak

Cited by 5 publications

References 18 publications

Anomalous transport and multi-scale drift turbulence dynamics in tokamak ohmic discharge as measured by high resolution diagnostics and modeled by full-fgyrokinetic code

Anomalous transport and multi-scale drift turbulence dynamics in tokamak ohmic discharge as measured by high resolution diagnostics and modeled by full-fgyrokinetic code

Numerical modeling of micro turbulence wave number spectra reconstruction using radial correlation reflectometry: I. O-mode reflectometry at the linear plasma density profile

Gyrokinetic full-torus simulations of ohmic tokamak plasmas in circular limiter configuration

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