Effect of scrape-off-layer current on reconstructed tokamak equilibrium

King, Jacob; Kruger, Scott; Groebner, R. J.; Hanson, J.D.; Hebert, J.D.; Held, Eric; Jepson, Joseph

doi:10.1063/1.4972822

Cited by 4 publications

(3 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This inconsistency will be removed in future modeling. The new solution is an equilibrium that closely resembles the original reconstruction with the exception of the open-flux currents and additional quantification of these methods will be described in a future manuscript [25]. This regenerated equilibrium is consistent with the core profiles that are measured by the high quality diagnostics on DIII-D.…”

Section: Extended Equilibrium Reconstruction For Nimrodsupporting

confidence: 61%

NIMROD modeling of quiescent H-mode: reconstruction considerations and saturation mechanism

et al. 2016

View full text Add to dashboard Cite

Section: Extended Equilibrium Reconstruction For Nimrodsupporting

confidence: 61%

NIMROD modeling of quiescent H-mode: reconstruction considerations and saturation mechanism

et al. 2016

View full text Add to dashboard Cite

“…In Ref. [20], a quantitative analysis of the impact of adding SOL current to the equilibrium is presented. Re-solving the equilibrium and including SOL current and flow has little effect on the linear analysis, but is critical for nonlinear simulations as it eliminates discontinuities in current and flow at the LCFS.…”

Section: Numerical Formulation Of the Problemmentioning

confidence: 99%

MHD modeling of a DIII-D low-torque QH-mode discharge and comparison to observations

et al. 2017

Self Cite

View full text Add to dashboard Cite

Extended-MHD modeling of DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 2002] QH-mode discharges with nonlinear NIMROD [C. R. Sovinec et al., JCP 195, 355 2004] simulations saturates into a turbulent state, but does not saturate when the steady-state flow inferred from measurements is not included. This is consistent with the experimental observations of the quiescent regime on DIII-D. The simulation with flow develops into a saturated turbulent state where the n φ =1 and 2 toroidal modes become dominant through an inverse cascade. Each mode in the range of n φ =1-5 is dominant at a different time. Consistent with experimental observations during QH-mode, the simulated state leads to large particle transport relative to the thermal transport. Analysis shows that the amplitude and phase of the density and temperature perturbations differ resulting in greater fluctuation-induced convective particle transport relative to the convective thermal transport. Comparison to magnetic-coil measurements shows rotation frequencies differ between the simulation and experiment which indicates that more sophisticated extended-MHD two-fluid modeling is required.

show abstract

“…This discontinuity is unacceptable for non-linear simulations where simulation extend across the separatrix. To fix this problem, we use the NIMEQ solver [19] to re-solve the Grad-Shafranov equation across the separatrix with smooth profiles as described in references [8,20]. This not only gives continuity across the separatrix, but gives a high quality equilibrium that helps nonlinear simulations.…”

Section: Characterizing Initial Conditions For Non-linear Simulationsmentioning

confidence: 99%

Towards validated MHD modeling of edge harmonic oscillation in DIII-D QH-mode discharges

et al. 2020

Self Cite

View full text Add to dashboard Cite

The extended-MHD NIMROD code (Sovinec C.R. and King J.R. 2010 J. Comput. Phys. 229 5803) is used to simulate the dynamics of an edge harmonic oscillation (EHO) in quiescent H-mode (QH-mode) DIII-D (Luxon J.L. 2002 Nucl. Fusion 42 614) discharge 163 518. EHOs observed in non-linear MHD simulations have n = 1 and n = 2 as dominant modes akin the DIII-D experiment. Kinetic equilibrium reconstructions during the time of the fully-developed EHO include the effect of the MHD profile relaxation and are found below the stability boundary. This paper discusses methods to include additional instability drives to the experimental equilibria in order to trigger EHO formation. The experimental equilibrium for the DIII-D discharge 163 518 is modified to include two levels of instability drive by increasing the experimental pressure gradient. In order to do a more direct comparison of the simulation results with the experiment, a synthetic BES diagnostic is used to compute cross-correlation and cross-power spectral densities associated with the simulated density perturbations. It is shown that the amplitude of the experimental density perturbations is between the computed density perturbation amplitude for the two levels of instability drive. The synthetic cross-power spectral density shows a transition from a double to a single peak in frequency when the BES analysis shifts from near the LCFS towards the steep gradient region of the pedestal. This observation is similar to the experiment, but the first peak frequency for the weak instability drive is found below the experimental frequencies, and the second peak for the strong instability drive is found above the experimental peak frequencies. However, these peak frequencies are in agreement with the local flow estimate and a MHD turbulence bursty behavior in the simulations with the strong instability drive.

show abstract

Effect of scrape-off-layer current on reconstructed tokamak equilibrium

Cited by 4 publications

References 41 publications

NIMROD modeling of quiescent H-mode: reconstruction considerations and saturation mechanism

NIMROD modeling of quiescent H-mode: reconstruction considerations and saturation mechanism

MHD modeling of a DIII-D low-torque QH-mode discharge and comparison to observations

Towards validated MHD modeling of edge harmonic oscillation in DIII-D QH-mode discharges

Contact Info

Product

Resources

About