Nonlinear simulation of edge localized mode with pressure profile modified by pellet injection through a BOUT++ three-field MHD model

Li, Mao; Sun, Jizhong; Wang, Yumin; Xia, Tianyang

doi:10.1016/j.nme.2020.100888

Cited by 5 publications

(6 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Section 5.7 finally, contains a very brief outlook. For investigations of ELMs and ELM control with other non-linear MHD codes, refer to the review provided in reference [3] and for more recent work to references [181][182][183][184][185][186][187][188][189][190][191] and references therein.…”

Section: Applications To Elms and Elm Controlmentioning

confidence: 99%

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

et al. 2021

View full text Add to dashboard Cite

JOREK is a massively parallel fully implicit non-linear extended magneto-hydrodynamic (MHD) code for realistic tokamak X-point plasmas. It has become a widely used versatile simulation code for studying large-scale plasma instabilities and their control and is continuously developed in an international community with strong involvements in the European fusion research programme and ITER organization. This article gives a comprehensive overview of the physics models implemented, numerical methods applied for solving the equations and physics studies performed with the code. A dedicated section highlights some of the verification work done for the code. A hierarchy of different physics models is available including a free boundary and resistive wall extension and hybrid kinetic-fluid models. The code allows for flux-surface aligned iso-parametric finite element grids in single and double X-point plasmas which can be extended to the true physical walls and uses a robust fully implicit time stepping. Particular focus is laid on plasma edge and scrape-off layer (SOL) physics as well as disruption related phenomena. Among the key results obtained with JOREK regarding plasma edge and SOL, are deep insights into the dynamics of edge localized modes (ELMs), ELM cycles, and ELM control by resonant magnetic perturbations, pellet injection, as well as by vertical magnetic kicks. Also ELM free regimes, detachment physics, the generation and transport of impurities during an ELM, and electrostatic turbulence in the pedestal region are investigated. Regarding disruptions, the focus is on the dynamics of the thermal quench (TQ) and current quench triggered by massive gas injection and shattered pellet injection, runaway electron (RE) dynamics as well as the RE interaction with MHD modes, and vertical displacement events. Also the seeding and suppression of tearing modes (TMs), the dynamics of naturally occurring TQs triggered by locked modes, and radiative collapses are being studied.

show abstract

Section: Applications To Elms and Elm Controlmentioning

confidence: 99%

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The BOUT++ framework is a good tool to study the tokamak edge plasma physics, which has successfully simulated the ELM crash process [29][30][31]. Based on this framework, the turbulence models containing the effect of RMP [32], HCFs [13] and pellet injection [33] have been well developed respectively, to explain the ELM mitigation. Now, we extend the three-field two-fluid turbulence model of BOUT++ by adding the CM perturbation to analyze the effects of CM on ELM mitigation.…”

Section: Introductionmentioning

confidence: 99%

The simulation of ELMs mitigation by pedestal coherent mode in EAST using BOUT++

Li¹,

Xia²,

Zou³

et al. 2022

Nucl. Fusion

View full text Add to dashboard Cite

A general phenomenon that the edge localized modes (ELMs) can be effectively mitigated with the enhanced coherent modes (CMs) has been observed on EAST. For this phenomenon, the experimental statistical analysis and electromagnetic (EM) simulations have been performed. There is a threshold value of the CM intensity in the experiments, which plays a key role in ELMs mitigation. Through the ELITE and conventional BOUT++ analysis, we found that when the insignificant ELM and enhanced CM co-exist, the pedestal is located in unstable P-B region and the ELM is relatively large. The simulation results only using the experimental profiles without considering other factors cannot reproduce the no significant ELM experiment. The CM enhances the edge turbulence, which can control ELMs. Therefore, the effects of CM are considered to explain the ELM mitigation. Modifying the three-field reduced model in BOUT++, an imposed perturbation is added as the CM. The simulation results indicate that: without the CM, the ELM size belongs to the relative large ELM region; after considering the CM, the ELM is mitigated and the energy loss is reduced by about 44.5%. Analysis shows that the CM enhances the three-wave nonlinear interactions in the pedestal and reduces the phase coherence time (PCT) between the pressure and potential, which lead the perturbation to tend to be ‘multiple-mode’ coupling. The competition of free energy between the multiple modes leads to the lack of obvious filament structures and the decreased energy loss. The above reveals that there is a competitive relationship between turbulence and ELMs, and the CM-enhanced turbulence can effectively reduce ELM energy loss. In addition, through the parameter scanning, there is a threshold of the amplitude A, which is consistent with the statistical results in the experiments.

show abstract

“…Thus, the introduced local pressure comes only from the enhanced background density. Furthermore, a double-Gaussian model, which is a modified version of that used in [22], is introduced to describe the 2D distribution of the enhanced part of the pelletaffected pressure according to the results in [20]. It is in the form of the following function:…”

Section: Model and Simulation Setupmentioning

confidence: 99%

“…In [20], the sizable Li pellet (⩾0.46 mm in diameter) reached the pedestal top, and a smaller one 0.26 mm in diameter was deposited within the steep-gradient pedestal region. Based on the SOLPS results, a BOUT++ simulation [22] was conducted to study the effect of the pressure profile changed by pellet injection on a natural ELM with a circular cross-section in toroidal equilibrium. However, neither study explored further the physical mechanism of pellet ELM triggering on a turbulent scale.…”

Section: Introductionmentioning

confidence: 99%

Simulation of triggering and evolution of ELM by pellet injection in EAST under BOUT++ framework

Li,

Xia,

Sun

et al. 2024

Nucl. Fusion

Self Cite

View full text Add to dashboard Cite

A BOUT ++ three-field MHD model is employed to study the triggering and evolution of ELM by Li pellet injected along the outer mid-plane in the EAST configuration. The linear simulation shows that compared with a big deposition on the pedestal top (scenario I), a smaller deposition within the steep-gradient pedestal region (scenario II) can stimulate much larger linear growth rates of all-n peeling-ballooning modes (PBMs). The nonlinear simulation shows that there exists a pellet size threshold for ELM triggering for two deposition locations; the threshold for scenario I predicted in the present work matches EAST observation well. In comparison of the two scenarios, a smaller deposition is sufficient to trigger an ELM in a much shorter time in scenario II, whose ELM size is comparable to that in scenario I. The conclusion confirms the previous DIII-D and ASDEX-Upgrade observations, suggesting that the steep-gradient pedestal region be a favorable deposition location for ELM triggering with minimum pellet size. Simulation analyses also find that the positive radial gradient of the hump-like pressure profile in the outer mid-plane induced by the pellet deposition plays a different role in the two scenarios: in scenario I, the force resulting from the gradient hinders the outflow of core plasmas and in return, the perturbation is suppressed from spreading inward after ELM crashes; in scenario II, with a sizable deposition, the gradient results in another competitive perturbation growth region during the linear phase, thus dispersing the free energy and reducing the efficiency of destabilizing PBMs by pellet injection. The suppressing effect of saturated zonal flow on other modes, the short ELM fast crash phase, and the restricting transport effect of the positive radial pressure gradient work together to constrain the pedestal energy loss, especially when the pellet deposition amount is high.

show abstract

Nonlinear simulation of edge localized mode with pressure profile modified by pellet injection through a BOUT++ three-field MHD model

Cited by 5 publications

References 24 publications

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas

The simulation of ELMs mitigation by pedestal coherent mode in EAST using BOUT++

Simulation of triggering and evolution of ELM by pellet injection in EAST under BOUT++ framework

Contact Info

Product

Resources

About