A Suitable Boundary Condition for Bounded Plasma Simulation without Sheath Resolution

Parker, Scott; Procassini, R.J.; Birdsall, C.K.; Cohen, B. I.

doi:10.1006/jcph.1993.1005

Cited by 65 publications

(44 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the sum of Debye sheath, quasi-neutral pre-sheath, and the parallel potential variation that are not resolved by the gyroradius grid needs to be handled as a sub-grid phenomenon: XGC1 uses a modified logical sheath boundary condition. 55 The total logical sub-grid sheath potential is then determined by counting the …”

Section: E Logical Sheathmentioning

confidence: 99%

A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1

et al. 2018

View full text Add to dashboard Cite

Article:Ku, S., Chang, C. S., Hager, R. et al. (9 more authors) (2018) A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1. Physics of Plasmas. 056107. ISSN 1089-7674 https://doi.org/10.1063/1.5020792 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Items deposited in White Rose Research Online are protected by copyright, with all rights reserved unless indicated otherwise. They may be downloaded and/or printed for private study, or other acts as permitted by national copyright laws. The publisher or other rights holders may allow further reproduction and re-use of the full text version. This is indicated by the licence information on the White Rose Research Online record for the item. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request.A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1 A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1 A fast edge turbulence suppression event has been simulated in the electrostatic version of the gyrokinetic particle-in-cell code XGC1 in a realistic diverted tokamak edge geometry under neutral particle recycling. The results show that the sequence of turbulent Reynolds stress followed by neoclassical ion orbit-loss driven together conspire to form the sustaining radial electric field shear and to quench turbulent transport just inside the last closed magnetic flux surface. The main suppression action is located in a thin radial layer around w N ' 0:96-0:98, where w N is the normalized poloidal flux, with the time scale $0:1ms.Published by AIP Publishing. https://doi

show abstract

Section: E Logical Sheathmentioning

confidence: 99%

A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In the open field line region, XGC0 takes a simplified approach: On each flux surface volume, the fluxfunction electrostatic potential is determined by the requirement that the perpendicular drift losses across the magnetic field and the parallel losses to the first wall to combine together to satisfy the ambipolarity condition between ions and electrons. This is a generalization of the logical sheath concept, 33 which considered only the parallel losses of electrons and ions to the wall. As the separatrix is approached from the scrape-off side, the magnetic connection length becomes infinite, the parallel loss vanishes, hJ NC Á rwi determines hUi as in Eq.…”

Section: The Xgc0 Codementioning

confidence: 99%

Bootstrap current for the edge pedestal plasma in a diverted tokamak geometry

Koh

Chang

et al. 2012

Physics of Plasmas

View full text Add to dashboard Cite

The edge bootstrap current plays a critical role in the equilibrium and stability of the steep edge pedestal plasma. The pedestal plasma has an unconventional and difficult neoclassical property, as compared with the core plasma. It has a narrow passing particle region in velocity space that can be easily modified or destroyed by Coulomb collisions. At the same time, the edge pedestal plasma has steep pressure and electrostatic potential gradients whose scale-lengths are comparable with the ion banana width, and includes a magnetic separatrix surface, across which the topological properties of the magnetic field and particle orbits change abruptly. A driftkinetic particle code XGC0, equipped with a mass-momentum-energy conserving collision operator, is used to study the edge bootstrap current in a realistic diverted magnetic field geometry with a self-consistent radial electric field. When the edge electrons are in the weakly collisional banana regime, surprisingly, the present kinetic simulation confirms that the existing analytic expressions [represented by O. Sauter et al., Phys. Plasmas 6, 2834] are still valid in this unconventional region, except in a thin radial layer in contact with the magnetic separatrix. The agreement arises from the dominance of the electron contribution to the bootstrap current compared with ion contribution and from a reasonable separation of the trapped-passing dynamics without a strong collisional mixing. However, when the pedestal electrons are in plateau-collisional regime, there is significant deviation of numerical results from the existing analytic formulas, mainly due to large effective collisionality of the passing and the boundary layer trapped particles in edge region. In a conventional aspect ratio tokamak, the edge bootstrap current from kinetic simulation can be significantly less than that from the Sauter formula if the electron collisionality is high. On the other hand, when the aspect ratio is close to unity, the collisional edge bootstrap current can be significantly greater than that from the Sauter formula. Rapid toroidal rotation of the magnetic field lines at the high field side of a tight aspect-ratio tokamak is believed to be the cause of the different behavior. A new analytic fitting formula, as a simple modification to the Sauter formula, is obtained to bring the analytic expression to a better agreement with the edge kinetic simulation results. V C 2012 American Institute of Physics.

show abstract

“…In SOL, the sheath potential is obtained from a logical sheath method extended from Ref. [24], requiring that the sum of parallel and perpendicular (to B-field) charge losses vanishes.…”

Section: A Model Diii-d Plasma and The Simulation Proceduresmentioning

confidence: 99%

Plasma transport in stochastic magnetic field caused by vacuum resonant magnetic perturbations at diverted tokamak edge

et al. 2010

View full text Add to dashboard Cite

A kinetic transport simulation for the first 4 ms of the vacuum resonant magnetic perturbations (RMPs) application has been performed for the first time in realistic diveted DIII-D tokamak geometry [J. Luxon, Nucl. Fusion 42, 614 (2002)], with the self-consistent evaluation of the radial electric field and the plasma rotation. It is found that, due to the kinetic effects, the stochastic parallel thermal transport is significantly reduced when compared to the standard analytic model

show abstract

A Suitable Boundary Condition for Bounded Plasma Simulation without Sheath Resolution

Cited by 65 publications

References 0 publications

A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1

A fast low-to-high confinement mode bifurcation dynamics in the boundary-plasma gyrokinetic code XGC1

Bootstrap current for the edge pedestal plasma in a diverted tokamak geometry

Plasma transport in stochastic magnetic field caused by vacuum resonant magnetic perturbations at diverted tokamak edge

Contact Info

Product

Resources

About