CD-EXCALIBUR-FMS0054-RB-1_ExcaliburFusionModellingSystemD31SoftwareRequirementsSpecification
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.. meta::
   :description: technical note

   :keywords: ExCALIBUR,D3.1,Software,Requirements,Speciﬁcation,RB/1,Tokamak,Science,Requirements,Speciﬁcation,Abstract,This,document,provides,a,description,of,tokamak,science,physicists’,requirements,for,NEPTUNE.,It,forms,part,of,the,requirements,baseline,(RB).,UKAEA,REFERENCE,AND,APPROVAL,SHEET,Client,Reference:,UKAEA,Reference:,Issue:,Date:,CD/EXCALIBUR-,FMS/0054/RB/1,1.00,26,October,2021,Project,Name:,ExCALIBUR,Fusion,Modelling,System,Prepared,By:,Name,and,Department,Fulvio,Militello,James,Harrison,Signature,N/A,N/A,Date,5,November,2020,5,November,2020,Tok,Sci,Reviewed,By:,Wayne,Arter,26,October,2021,BD,Approved,By:,Rob,Akers,26,October,2021,Advanced,Dept.,Manager,Computing,2,Requirement,speciﬁcation,for,new,UKAEA,exhaust,code,(Tokamak,Science,Perspective):,The,new,UKAEA,Exhaust,code,needs,to,be,able,to,capture,parallel,and,perpendicular,transport,of,charged,and,neutral,particles,in,3D,,full,geometry,and,in,a,time,dependent,way.,Turbulence,should,be,self-consistently,modelled,,as,well,as,energy,transfer,physics,between,charged,parti-,cles,,neutrals,and,photons,(radiation).,While,perturbations,need,to,be,3D,,a,minimal,requirement,for,the,code,is,that,it,can,simulate,realistic,axisymmetric,equilibrium,conﬁgurations,with,complex,topologies,and,wall,designs.,The,aim,of,the,code,should,be,to:,1.,Efﬁciently,and,reliably,model,exhaust,in,next,generation,experiments,,like,e.g.,MAST-U,,JT60-SA,,and,especially,ITER,(the,latter,is,a,stringent,requirement,for,the,code).,2.,Allow,predictive,exhaust,capability,for,future,reactor,relevant,machines,like,STEP,or,DEMO.,Overall,capabilities,•,Hierarchical,approach,with,multiple,models,,going,from,low,ﬁdelity,(e.g.,laminar,ﬂuid,and,ﬂuid-kinetic,runs,in,2D),to,medium,ﬁdelity,(e.g.,ﬂuid,runs,with,neutrals,and,turbulence,–,multispecies,,but,with,reduced,number,of,species),and,high,ﬁdelity,(e.g.,full,kinetic,or,hybrid,kinetic/ﬂuid,runs,with,turbulence,and,multispecies,approach).,•,Numerically,efﬁciency,,obtained,for,example,through,scalability,to,large,number,of,cores,(given,the,expected,computational,resources,,the,code,should,be,designed,to,take:,∼1,week,for,low,ﬁdelity,parametric,scans;,(cid:46)1,month,for,medium-high,ﬁdelity,runs,for,advanced,design;,(cid:46)3,months,for,high,ﬁdelity,physics,studies).,•,Focus,on,stability,of,the,code,,using,(preferably),unconditionally,stable,numerical,schemes,and,capability,to,diagnose,and,re-start,failed,runs.,Ensure,a,small,failed,simulation,rate,for,common,conﬁgurations.,Provide,ccapability,to,model,exhaust,physics,all,the,way,from,sheath,limited,to,strongly,detached,regimes;,•,Modern,software,design,with,modular,approach,(independent,and,efﬁcient,libraries);,•,Ability,to,integrate,with,other,codes,(for,example,with,IMAS);,•,Modern,visualization,tools;,•,Accessibility,(output,easily,catalogued,and,interrogated,–,big,data);,•,Version,control,and,user,support.,Physics,model,•,General,requirements,for,the,plasma,model(s):,–,Equations,need,to,be,applicable,to,arbitrary,aspect,ratio,devices;,3,–,The,collision,operators,between,plasma,components,,plasma,and,impurities,and,plasma,and,neutrals,have,to,be,sufﬁciently,accurate,to,properly,describe,the,radiation,gener-,ated,and,the,energy,transfer,between,species;,–,Photon,opacity,effects,need,to,be,included,in,the,model;,–,The,equations,need,to,be,capable,of,dealing,with,multiple,species,in,non-trace,amounts,(at,least,D,,T,,He,and,seeding,impurities);,–,The,equations,should,not,rely,on,the,Boussinesq,approximation;,–,The,code,should,evolve,both,the,electron,and,ion,energy,(temperature),–,It,would,be,acceptable,to,have,only,axisymmetric,equilibria,,potentially,corrected,through,small,perturbations.,•,For,high,ﬁdelity,simulations:,–,In,high,ﬁdelity,simulations,,kinetic/ﬂuid,transition,for,both,plasma,and,neutrals,has,to,be,properly,captured,,potentially,using,a,multi-region,approach,exploiting,different,models,in,different,parts,of,the,machine,could,be,considered,(for,both,neutrals,and,plasma);,–,Boundary,conditions,need,to,consider,improved,sheath,physics,(collisional,&,shallow,angles);,–,Ideally,,the,model,should,be,able,to,treat,de-magnetized,ions,in,the,divertor,region;,–,Electromagnetic,effects,should,be,included,,but,a,perturbation,approach,would,be,ac-,ceptable;,•,Neutrals,and,impurities:,–,Different,levels,of,multispecies,capabilities,should,be,considered;,–,In,medium,to,high,ﬁdelity,models,,neutrals,and,heavy,species,should,be,treated,fully,kinetically,(the,latter,have,a,large,Larmor,radius,,the,former,potentially,low,collisionality,and,they,are,not,bound,by,the,magnetic,ﬁeld).,–,In,high,ﬁdelity,models,,dynamical,neutral,evolution,on,the,turbulence,time,scale,would,be,preferable,,if,possible;,–,Ability,to,model,pumps,(either,directly,or,via,pumping,surfaces),should,be,included;,–,Pellets,the,code,should,enable,simulation,of,,or,coupling,to,models,that,can,model,,pellet,fuelling.,Physics,capabilities:,The,code,needs,to,be,able,to,give,reliable,predictions,of:,•,Divertor,loads:,–,Reliable,calculation,of,upstream,particle,and,heat,ﬂux,proﬁles:,proper,drift,physics,and,upstream,turbulence;,4,–,Divertor,turbulence:,turbulence,spreading,in,the,divertor,region,,effect,of,magnetic,shear,next,to,the,X-point(s),to,understand,upstream/downstream,connection;,–,Multiﬂuid,capacity,to,model,radiation,and,detachment,physics;,–,Reliable,calculation,of,the,electric,ﬁeld,(collisionless,physics,near,the,separatrix,,proper,reﬂection,of,neutrals,at,the,target);,–,Able,to,capture,in/out,and,top/down,asymmetries,(geometry,,drifts,,radiation,and,de-,tachment),•,Wall,loads:,–,Should,be,able,to,predict,ﬁlamentary,transport,and,role,of,hot,ion,conﬁnement,(wall,erosion),–,Should,calculate,radiation,and,neutral,loads,(may,require,dedicated,modules,,same,for,divertor,loads);,•,Impurity,transport,,pumping,and,fueling:,–,Ability,to,track,low,(He,Be),,medium,(C,,N,,Ne),and,high,Z,impurities,(W,,Ar,,Xe),with,multiple,charge,states;,–,Reliable,kinetic,modelling,of,neutrals,to,assess,fueling,and,pumping,capacity;,–,Ability,to,handle,non-trace,species,(D,,T,,He,,seeded,species),,which,requires,new,closures,for,the,equations,(if,ﬂuid,,beyond,Braginskii,=⇒,Zhdanov,or,better);,–,Accurate,model,of,friction,forces,(turbulence,+,neoclassical,on,open,ﬁeld,lines);,–,In,high,ﬁdelity,models,,the,code,should,be,able,to,simulate,localized,gas,puffs,,via,injection,of,neutral,particles.,–,Dust,the,code,should,enable,coupling,to,codes,to,simulate,dust,generation,,transport,and,ablation,,via,exchange,of,ﬂuxes,and,sources.,Geometry,•,Ability,to,handle,complex,topologies,and,novel,geometries:,–,Capacity,to,treat,different,topologies,with,multiple,X-points,(>2),,possibly,in,a,dynamic,way,,or,at,least,implemented,in,a,way,that,does,not,preclude,time-varying,equilibria,being,modelled,in,future;,–,Ability,to,handle,singularities,in,the,grid,(null,points),or,to,develop,accurate,scheme(s),that,do,not,have,singularities;,–,Ability,to,interface,with,3D,CAD,designs,of,the,machine;,–,Capability,to,handle,conformal,grids,that,go,all,the,way,to,the,wall,for,both,neutrals,and,plasma;,–,Capability,to,treat,subdivertor,structures,(only,neutrals).,References,5

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