BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Challenges for modelling fusion plasmas - Wayne Arter (Culham Cent re for Fusion Energy) DTSTART:20191028T140000Z DTEND:20191028T144500Z UID:TALK134047@talks.cam.ac.uk CONTACT:INI IT DESCRIPTION:Modelling fusion plasmas presents many challenges\, so that it is reasonablethat many modelling codes still use simple \;nite di \;erence representations that makeit relatively easy to explore new physic al processes and preserve numerical stability [1].However\, October 2019 a nnouncements by UK government have given UKAEA thechallenge of designing a nuclear fusion reactor in the next 5 years\, plus a funding elementfor up grading existing software both for Exascale and to meet the design challen ge. Oneoption under examination is the use of high order '\;spectrally accurate'\; elements.The biggest modelling problem is still that of tur bulence mostly at relatively low plasmacollisionality. Speci \;cally no n-dissipative issues are the tracking of plasma particle orbitsbetween col lisions\, sometimes reducing to tracing lines of divergence-free magnetic& #12\;eld. These particles then build into a Maxwell{Vlasov solver\, for wh ich many di \;erentnumerical representations\, exploiting low collisona lity and the presence of a strong\,directed magnetic \;eld have been e xplored [2]. One such is ideal MHD\, where I haveexplored the use of the L ie derivative [3\, 4]. Some further speculations as to the likelyrole of L ie (and spectral accuracy) in solving Vlasov{Maxwell\, its approximations andtheir ensembles\, and interactions between the di \;erent approximat ions\, in the Exascaleera will be presented.This work was funded by the RC UK Energy Programme and the European Communities under thecontract of Asso ciation between EURATOM and CCFE.[1] B.D. Dudson\, A. Allen\, G. Breyianni s\, E. Brugger\, J. Buchanan\, L. Easy\, S. Farley\, I. Joseph\,M. Kim\, A .D. McGann\, et al. BOUT++: Recent and current developments. Journal of Pl asmaPhysics\, 81(01):365810104\, 2015.[2] W. Arter. Numerical simulation o f magnetic fusion plasmas. Reports on Progress in Physics\,58:1{59\, 1995. [3] W. Arter. Potential Vorticity Formulation of Compressible Magwnetohydr odynamics. PhysicalReview Letters\, 110(1):015004\, 2013.[4] W. Arter. Bey ond Linear Fields: the Lie{Taylor Expansion. Proc Roy Soc A\, 473:20160525 \, 2017. LOCATION:Seminar Room 2\, Newton Institute END:VEVENT END:VCALENDAR