Simulating the effect of poloidal particle source on the bootstrap current and benchmarking to analytic estimates in tokamak edge pedestal

Kiviniemi, Timo; Virtanen, Antti; Systä, Heikki; Chôné, L.; Leerink, S.; Hirvijoki, Eero

doi:10.1088/1361-6587/ac2616

Cited by 3 publications

(8 citation statements)

References 36 publications

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“…There are various ways of calculating the bootstrap current that involve either direct solution of the neoclassical equations [4,5] or a fitting of the numerical solution over various parameter ranges [6,7]. Members of our collaboration have used the global full f gyrokinetic code ELMFIRE [8] first to benchmark the Hager and Sauter models [9]. It was found that these two formulae agree with ELMFIRE in the regime where there is no Shafranov shift and low collisionality, which is relevant for ELMFIRE.…”

Section: Recent Work On Reactor Relevant Pedestalsmentioning

confidence: 99%

“…It was found that these two formulae agree with ELMFIRE in the regime where there is no Shafranov shift and low collisionality, which is relevant for ELMFIRE. Further, ELMFIRE has been used to assess the effect of poloidal variation of density on the bootstrap current [9]. Initial results indicate that there is an effect which should be investigated further.…”

Section: Recent Work On Reactor Relevant Pedestalsmentioning

confidence: 99%

“…We consider the impact of this, as well as that of the density variation, on the incremental bootstrap current. A numerical investigation of this problem has been carried out using ELMFIRE [9]. Previous work on understanding the effect of a poloidal density variation on transport was carried out by Solano and Hazeltine [35].…”

Section: Effect Of a Poloidal Variation Of The Plasma Density On The ...mentioning

confidence: 99%

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Towards understanding reactor relevant tokamak pedestals

et al. 2021

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The physics of the tokamak pedestal is still not fully understood, for example there is no fully predictive model for the pedestal height and width. However, the pedestal is key in determining the fusion power for a given scenario. If we can improve our understanding of reactor relevant pedestals we will improve our confidence in designing potential fusion power plants. Work has been carried out as part of a collaboration on reactor relevant pedestal physics. We report some of the results in detail here and review some of the wider work which will be reported in full elsewhere. First, we attempt to use a gyrokinetic-based calculation to eliminate the pedestal top density as a model input for Europed/EPED pedestal predictions. We assume power balance at the top of the pedestal, that is, the heat flux crossing the separatrix must be equal to the heat source at the top of the pedestal and investigate the consequences of this assumption. Unfortunately, this method was not successful. Second, we investigate the effects of non flux surface density on the bootstrap current. Third, type I ELMs will not be tolerable for a reactor relevant regime due to the damage that they are expected to cause to plasma facing components. In recent years various methods of running tokamak plasmas without large ELMs have been developed. These include small and no ELM regimes, the use of resonant magnetic perturbations and the use of vertical kicks. We discuss the quiescent H-mode here. Finally we give a summary and directions for future work.

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Section: Recent Work On Reactor Relevant Pedestalsmentioning

confidence: 99%

Section: Recent Work On Reactor Relevant Pedestalsmentioning

confidence: 99%

Section: Effect Of a Poloidal Variation Of The Plasma Density On The ...mentioning

confidence: 99%

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Towards understanding reactor relevant tokamak pedestals

et al. 2021

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“…Further numerical details can be found in recent papers, [ 10,11 ] while a revised set of equations of motion for the new version of the code can be found. [ 12 ]…”

Section: The Gyrokinetic Code Elmfirementioning

confidence: 99%

“…Further numerical details can be found in recent papers, [10,11] while a revised set of equations of motion for the new version of the code can be found. [12] The first transport barrier simulations reported [8] were done with the early ELMFIRE code version. [13] After that, several upgrades have been done.…”

Section: The Gyrokinetic Code Elmfirementioning

confidence: 99%

Revisiting the improved core confinement simulations for FT‐2 tokamak

Iorio

Chôné

Gusakov

et al. 2022

Contributions to Plasma Physics

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In the present paper, we revisit observations performed in FT-2 tokamak from previous works. Improvements of core confinement are observed and believed to be caused by wide orbits going from collisionless to collisional regimes. Similar phenomena can occur whenever gradient lengths are comparable to the orbit widths at the top of the pedestal and the loss cone is continuously and increasingly filled by heated particles, collisions and turbulent effects. The lower hybrid heating operator is introduced into the ELMFIRE code to increase the ion temperature during the simulations while keeping the edge temperature low with logical boundary condition at the limiter. Particular focus is given on how the radial electric field deviates from the neoclassical value while introducing turbulent effects.

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Numerical study of limits of neoclassical theory in the plateau regime in the presence of impurities

Iorio,

Kiviniemi,

Hirvijoki

et al. 2023

Contrib. Plasma Phys

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This paper presents a numerical simulation to test the corrections to the radial electric field in the presence of impurities for tokamak devices whose main ions are in the plateau regime. The effects due to the presence of impurity density variation in a pedestal tokamak are known to generate conditions where conventional neoclassical theory is no longer valid. It is found that for a specific axisymmetric concentric magnetic field, the presence of steep radial gradients for both temperature and density translates in a correction to the radial electric field. We anticipate that comparisons to the Landreman–Fülöp–Guszejnov model display good agreement for both the analytic approximation and numerically solved value of the normalized density when low impurity concentration and atomic charge state cases are considered, coupled with values of the ordering parameter . Higher values of the latter reveal better agreement to the neoclassical Hazeltine–Hinton formula, suggesting a discrepancy with the validity threshold of the model.

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Simulating the effect of poloidal particle source on the bootstrap current and benchmarking to analytic estimates in tokamak edge pedestal

Cited by 3 publications

References 36 publications

Towards understanding reactor relevant tokamak pedestals

Towards understanding reactor relevant tokamak pedestals

Revisiting the improved core confinement simulations for FT‐2 tokamak

Numerical study of limits of neoclassical theory in the plateau regime in the presence of impurities

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