Madsen, Jens

Naulin, Volker

Nielsen, Anders Henry

Rasmussen, Jens Juul

Thrysøe, Alexander Simon

Online Research Database In Technology

                       General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.  • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal   If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.     Downloaded from orbit.dtu.dk on: Dec 18, 2017Gas puff fuelling simulation with a combined neutral/HESEL modelThrysøe, Alexander Simon; Madsen, Jens; Naulin, Volker; Nielsen, Anders Henry; Rasmussen, Jens JuulPublication date:2016Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Thrysøe, A. S., Madsen, J., Naulin, V., Nielsen, A. H., & Rasmussen, J. J. (2016). Gas puff fuelling simulationwith a combined neutral/HESEL model. Abstract from 43rd EPS Conference on Plasma Physics, Leuven,Belgium.Gas puff fuelling simulation with a combined neutral/HESEL modelA.S. Thrysøe1, J. Madsen1, V. Naulin1, A.H. Nielsen1, J. Juul Rasmussen11 PPFE, Department of Physics, DTU, DK-2800 Kgs. Lyngby, DenmarkIn future magnetic confinement fusion devices, such as ITER, high efficiency fuelling with deeppenetration is required for maintaining a sufficient plasma core density. One possible fuellingmethod is gas puffing, in which neutral molecules are puffed into the scrape-off layer (SOL),where they dissociate, and if the resulting atoms are ionized inside the last closed flux surface(LCFS), they fuel the plasma effectively.We simulate gas puff fuelling by implementing a module for neutral particles into the HESELmodel [1]. The HESEL model is a four-field model based on the Braginskii equations on a2D drift-plane at the outboard mid-plane, and is capable of describing interchange-driven lowfrequency turbulence. The domain includes the closed field line edge region as well as the openfield line SOL region.It is investigated to what extend the artificial density source in the HESEL model can bereplaced by a more accurate model for the fuelling process by implementing a self consistentdynamical model for the neutral particles. This gives an estimate for the amount of neutralsfrom gas puffing, which is required to fuel the plasma.For the fuelling to maintain the amount of plasma particles, the ionization of neutrals insidethe LCFS must (on average) balance the integrated flux of plasma across the LCFS, i.e.,〈∫edgedV nN〈σizv〉〉t=〈∫LCFSdAΓn〉t, (1)where n is the electron density, N is the neutral atom density, 〈σizv〉 is the ionization rate coeffi-cient, Γn is the particle flux, and 〈 · 〉t denotes the temporal average. The volume integral on theLHS is over the volume inside LCFS, and the surface integral on the RHS is over the LCFS.For typical gas puffing rates it is found that the resulting fuelling only accounts for approx-imately 15-20% of the required plasma density source. We believe this can be explained bythe fact that the domain in the HESEL model is located at the outboard mid-plane, in whicharea the far highest turbulent flux is concentrated, whereas the gas puffing may reasonably beassumed to be more uniformly distributed across the plasma surface. Thus, accounting for thisissue would lead towards a much better balance between the fuelling and the plasma lossesthrough the turbulent flux, which indeed is the dominating loss channel.References[1] J. Madsen et al., (2016), submitted to PoP43rd EPS Conference on Plasma Physics O4.116

Gas puff fuelling simulation with a combined neutral/HESEL model

http://orbit.dtu.dk/ws/files/128856028/Untitled.pdf

Gas puff fuelling simulation with a combined neutral/HESEL model

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology