Plasmoid-mediated reconnection during nonlinear peeling–ballooning edge-localized modes

Ebrahimi, Fatima; Bhattacharjee, Amitava

doi:10.1088/1741-4326/ad0062

Cited by 2 publications

(1 citation statement)

References 57 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, nonlinear mode-mode coupling might also be limited in these simulations. As illustrated in figure 4 of [34], mode-mode coupling can exert a significant effect on the saturation of both low n and high n ELMs. The full nonlinear dynamics may not be captured by only keeping specific toroidal harmonics [35].…”

Section: Comparison Of Elm Activities Between H-mode and Super H-modementioning

confidence: 99%

Nonlinear simulations of the peeling-ballooning instability of super H-modes in the HL-3 tokamak

Zhu,

Zhong,

Zou

et al. 2024

Nucl. Fusion

View full text Add to dashboard Cite

As the newly built tokamak in China, HL-3 is going to explore high performance operation scenario such as super H-mode. The energy confinement and core parameters in super H-mode can be much larger than that in normal H-mode. Based on the pedestal simulation code EPED, the operation space of super H-mode is obtained in HL-3. Magnetic shear decreases with increasing triangularity, and then the super H-mode can be achieved. The threshold of triangularity for accessing super H-mode in HL-3 is around 0.4. By using BOUT++, nonlinear simulation study of the pedestal instabilities in super H-mode equilibrium is executed for the first time. As expected, low n peeling mode which can cause much energy loss (17%) from the pedestal region is dominant in super H-mode. Such a big collapse at pedestal region will lead the transition of super H-mode to H-mode. It is crucial to expand the parameter space of the super H-mode or mitigate the ELM size for sustaining the super H-mode operation. E×B velocity shear is found to play an important role for controlling the ELMs in HL-3. On the one hand, small E×B velocity shear leads to large growth rate but small ELM size around peeling boundary. ELM size is closely related with both of growth rate of peeling-ballooning mode and duration time of linear phase. On the other hand, large E×B velocity shear can stabilize the instabilities near ballooning boundary, and then the parameter space of super H-mode will be enlarged.

show abstract

Section: Comparison Of Elm Activities Between H-mode and Super H-modementioning

confidence: 99%

Nonlinear simulations of the peeling-ballooning instability of super H-modes in the HL-3 tokamak

Zhu,

Zhong,

Zou

et al. 2024

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

Two-stage crash process in resistive drift ballooning mode driven ELM crash

Seto,

Xu,

Dudson

et al. 2024

Physics of Plasmas

View full text Add to dashboard Cite

We report a two-stage crash process in edge localized mode (ELM) driven by resistive drift-ballooning modes (RDBMs) numerically simulated in a full annular torus domain with a scale-separated four-field reduced MHD (RMHD) model using the BOUT++ framework. In the early nonlinear phase, the small first crash is triggered by linearly unstable RDBMs, and m/n=2/1 magnetic islands are nonlinearly excited by nonlinear coupling of RDBMs as well as their higher harmonics. Here, m is the poloidal mode number, n is the toroidal mode number, the q = 2 rational surface exists near the pressure gradient peak, and q is the safety factor. Simultaneously, middle-n RDBM turbulence develops but is poloidally localized around X-points of the magnetic islands, leading to the small energy loss. The second large crash occurs in the late nonlinear phase. Higher harmonics of m/n=2/1 magnetic islands well develop around the q = 2 surface via nonlinear coupling and make the magnetic field stochastic by magnetic island overlapping. Turbulence heat transport develops at X-points of higher harmonics of m/n=2/1 magnetic islands, resulting in the turbulence spreading in the poloidal direction. The large second crash is triggered when the turbulence covers the whole poloidal region so that the magnetic island generation and magnetic field stochastization before the large crash can be interpreted as ELM precursors. It is concluded that the ELM trigger is attributed to the turbulent spreading in the poloidal direction in synchronization with the magnetic field stochastization and the crash is driven by E × B convection rather than the conventional Rechester–Rosenbluth anomalous electron heat transport.

show abstract

Plasmoid-mediated reconnection during nonlinear peeling–ballooning edge-localized modes

Cited by 2 publications

References 57 publications

Nonlinear simulations of the peeling-ballooning instability of super H-modes in the HL-3 tokamak

Nonlinear simulations of the peeling-ballooning instability of super H-modes in the HL-3 tokamak

Two-stage crash process in resistive drift ballooning mode driven ELM crash

Contact Info

Product

Resources

About