Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

Hong, Jin; Henderson, S.; Kim, Kimin; Seon, C. R.; Song, In‐Hyuck; Lee, H.Y.; Jang, Juhyeok; Park, Jae Sun; Lee, S.G.; Lee, J.H.; Lee, Seung Hun; Hong, Suk–Ho; Choe, Wonho

doi:10.1088/1741-4326/aa5333

Cited by 15 publications

(11 citation statements)

References 32 publications

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“…7 may ease the suppression of ZF on ambient CTEM, thus, the transport level of impurity driven by CTEM turbulence might become higher. This might be possibly consistent with the results in gyrokinetic simulation [12], experiments [45] and the references therein, where the electron dominated auxiliary heating is widely recognized to be beneficial for transporting impurity. In particular, we also explore the effects of the temperature ratio between electron and high temperature He 2+ in Fig.…”

Section: Impact Of Impurities On Zf Growth Ratesupporting

confidence: 87%

Impact of impurities on zonal flow driven by trapped electron mode turbulence

Guo¹,

Wang²,

Zhuang³

2017

Nucl. Fusion

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The impact of impurities on the generation of zonal flow (ZF) driven by collisonless trapped electron mode (CTEM) turbulence in deuterium (D)-tritium (T) plasmas is investigated. The expression for ZF growth rate with impurities is derived by balancing the ZF potential shielded by polarization effects and the ZF modulated radial turbulent current. Then, it is shown that the maximum normalized ZF growth rate is reduced by the presence of the fully ionized non-trace light impurities with relatively flat density profile, and slightly reduced by highly ionized trace tungsten (W). While, the maximum normalized ZF growth rate can be also enhanced by fully ionized non-trace light impurities with relatively steep density profile. In particular, the effects of high temperature helium from D-T reaction on ZF depend on the temperature ratio between electron and high temperature helium. The possible relevance of our findings to recent experimental results and future burning plasmas is also discussed.

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Section: Impact Of Impurities On Zf Growth Ratesupporting

confidence: 87%

Impact of impurities on zonal flow driven by trapped electron mode turbulence

Guo¹,

Wang²,

Zhuang³

2017

Nucl. Fusion

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“…Thus, the diffusivity is consequently determined and predicted by changes in input α jn (figure 13(b)). It is important to note that the calculated D (ρ) is in good agreement with the results of the standard modelling of JET [25] and KSTAR [61,65], but only for packed n Ar (ρ) profiles (the C and D cases). In contrast, for the flat and hollow profiles n Ar (ρ) (the A and B cases) there is no clear correspondence.…”

Section: Ar Density Profilessupporting

confidence: 72%

Impurity charge state transport in tokamak and stellarator plasmas

Shurygin

2020

Nucl. Fusion

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The standard one-dimensional formulation of impurity transport has proved to be highly questionable for impurities with medium/high Z, and is unsuitable for tungsten. This allows to reveal an inconsistent interpretation of the coupling between particle transport and ionization/ recombination processes. A discrete two-dimensional (2D) Fokker-Planck-Kolmogorov equation with charge and radius variables is proposed to study impurity equilibrium and transport in tokamak and stellarator plasmas. The impurity behaviour is consistently considered in terms of a 2D Markovian stochastic process, which has a complex structure according to probabilistic laws that include particle transport as part of a more general impurity charge state transport. It is found that a self-consistent 2D Markovian impurity equilibrium has the consequence that particle transport corresponding to the stationary state is governed by ionization and recombination processes, which are statistically independent of the particle motion. These generalised 2D coronal equilibrium conditions, usually observed for heavy impurities in experiments, turn out to be the stationary solution of the discrete 2D equation introduced and are justified in a discrete 2D grid model of impurity equilibrium. A complete analysis of the simplest discrete 2D equilibrium cell provides the basis for a general solution, while the grid model is reduced to a set of such local equilibrium cells using a pseudo-state technique.Modelling of the density profiles of carbon, argon and tungsten impurities is carried out by TICS (transport of impurity charge states) code developed using available experimental data. It is found that the introduced equilibrium function, which is a discrete profile of the ratios of reduced ionization and recombination rates, systematically predicts the central accumulation, equilibrium and radial transport of impurities in H-and L-mode and ion transport barrier plasmas, in agreement with the experimental data.

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“…Impurity peaking in the core plasma is not taken into account in the model but this effect might have an influence on the plasma parameters. However, usage of powerful ECR heating normally enhances the particle transport and reduces impurity accumulation in the plasma core [26][27][28]. The detailed profile modelling would shed light on the effect of neon on the plasma core.…”

Section: Discussionmentioning

confidence: 99%

Integrated modelling of core and divertor plasmas for the DEMO Fusion Neutron Source hybrid facility

et al. 2019

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A steady state regime for the tokamak-based DEMO Fusion Neutron Source (DEMO-FNS) with parameters R/a = 3.2 m/1.0 m, B = 5 Т, Ipl = 4–5 MA, PNBI = 30 MW and РECR = 6 МW is studied using coupled simulations of the central and divertor plasma. In our analysis, the divertor plasma state is determined by the values of the heat flux PSOL, the pressure of the neutrals in the divertor p n and the total number of neon particles NNe outside the separatrix. As the boundary conditions for the core plasma, we use the values at the separatrix of the electron density, ne_sep, and temperatures of the ions, Ti_sep, and electrons, Te_sep, the concentration of the neon impurity normalized to the electron density at the separatrix, cNe = ∑ nNe/ne_sep and the hydrogen neutral influx into the core plasma, Γ0sep. In the divertor region, all the values are calculated using the SOLPS4.3 code for a number of operating points (~150 in our case) with different values of PSOL, p n and NNe. Then the calculation results are approximated by analytical formulas. Power balance in the core plasma is calculated using the ASTRA and NUBEAM codes. The hydrogen (deuterium and tritium) density is modelled taking into account the sources generated by the neutrals originating from the divertor region, as well as by injection of fast atoms and pellet injection. The neon density and radiation in the main plasma are simulated using the STRAHL code. As the result of the simulations, the operational regime of DEMO-FNS is determined, in which the heat loading onto the divertor targets remains at the acceptable level below 10 MW m−2, the divertor plasma does not transit into the ‘full detachment’ mode and the plasma in a double-null separatrix configuration is kept up–down symmetric. Variations of these conditions versus the impurity level and confinement parameters are investigated and discussed.

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Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

Cited by 15 publications

References 32 publications

Impact of impurities on zonal flow driven by trapped electron mode turbulence

Impact of impurities on zonal flow driven by trapped electron mode turbulence

Impurity charge state transport in tokamak and stellarator plasmas

Integrated modelling of core and divertor plasmas for the DEMO Fusion Neutron Source hybrid facility

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