The Effects of E r xb Flow Shear Profile on the Formation of Internal Transport Barrier in ITER

Transcription

1 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 Th Effcts of E r xb Flow Shar Profil on th Formation of Intrnal Transport Barrir in ITER Thawatchai Onjun Plasma and Fusion Rsarch Unit, Sirindhorn Intrnational Institut of Tchnology, Thammasat Univrsity, Pathum Thani, 111, Thailand Abstract An improvmnt of nuclar fusion prformanc in ITER tokamak with an intrnal transport barrir (ITB) is invstigatd. Slf-consistnt simulations of ITER in th standard H- mod scnario with th prsnc of an ITB ar carrid out using a 1.5D BALDUR intgratd prdictiv modling cod. In ths simulations, a vrsion of th Mixd Bohm/gyro-Bohm (Mixd B/gB) cor transport modl that includs ITB ffcts is usd to comput th volution of plasma profils. In this transport modl, th transport in th cor rgion can b stabilizd by th influnc of E r B flow shar and magntic shar. To illustrat th H-mod plasma proprtis, th boundary conditions in ths simulations ar dscribd using th pdstal tmpratur modl basd on th magntic and flow shar stabilization width concpt, togthr with th infinit-n ballooning stability concpt. Th combination of Mixd B/gB transport modl with ITB ffcts, togthr with th pdstal modl, is usd to simulat th tim volution of tmpratur, dnsity, and currnt profils for th ITER plasmas. Th prsnc of ITB rsults in complicatd scnarios, that can yild improvd prformanc, compard with standard H-mod dischargs. It is found that th formation of ITBs has a strong impact on both lctron and ion tmpratur profils, spcially nar th cntr of th plasma; whil only small impact is found on th lctron dnsity. Whn th ffct of an ITB is not includd, th prdictd cntral ion tmpratur is just abov 1 kv. With an ITB includd in th simulation, th cntral ion tmpratur can significantly incras up to th rang of 3 kv, dpnding on th dtails of E r B flow shar profil. Th incras of cntral tmpratur rsults in a significant improvmnt in th alpha powr production and, consquntly, th fusion prformanc. It is obsrvd that th thrmal and particl diffusivitis in most of th plasma cor ar smallr in th simulations with an ITB includd than in thos without th ITB. This rduction in th diffusivity rsults in strongr gradints and, consquntly, highr valus of th cntral tmpratur and dnsity. Kywords: Fusion, Plasma, Tokamak, H-mod, ITER, ITB, ETB 1. Introduction In ordr to achiv a significant fusion raction rat insid a nuclar fusion ractor, th ability to hat and contain high tmpratur plasmas insid th ractor is strongly rquird. Sinc th high confinmnt mod (H-mod) discharg [1] in tokamaks gnrally yilds xcllnt nrgy confinmnt and has accptabl particl transport rats for impurity control, futur nuclar fusion xprimnts such as th Intrnational Thrmonuclar Exprimntal Ractor (ITER) [], which aim to dmonstrat th scintific and tchnological 14

2 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 fasibility of nuclar fusion nrgy using th magntic confinmnt fusion concpt, ar dsignd to oprat in th H-mod rgim. It has bn widly obsrvd in many xprimnts from various tokamaks that th prformanc of an H-mod discharg can b furthr improvd with th formation of a transport barrir insid th plasma, calld an intrnal transport barrir (ITB) [3]. In gnral, th formation of an ITB is associatd with th E r B flow shar. Th prsnc of an ITBs du to E r B flow shar in H-mod plasmas is likly to rsult in an improvd scnario that yilds highr plasma tmpraturs and, consquntly, fusion powr production, which is mor suitabl for futur nuclar fusion xprimnts. In rcnt yars, prdictions of ITER prformanc in th standard typ I ELMy H-mod scnario using intgratd prdictiv modling cods hav bn intnsivly studid [4-1]. For xampl, th BALDUR intgratd prdictiv modling cod with Mixd Bohm/gyroBohm (Mixd B/gB) and MMM95 anomalous cor transport modls wr usd to prdict th prformanc of ITER [4, 6-8]. Th prformanc of ITER was valuatd in trms of th nuclar fusion powr production and th fusion Q, which is th ratio of fusion powr (to nutrons and alpha particls) to th applid auxiliary hating powr. A wid rang of prformanc is prdictd, dpnding on th choic of plasma dnsity, hating powr, impurity concntration and assumptions about th cor transport modls mployd in th simulations. In th rcnt work by T Onjun t al. [6, 7], th simulations of ITER wr carrid out with Mixd B/gB and MMM95 cor transport modl and diffrnt dg transport barrirs ETB modls. It was found in all ETB modls that th prdictd prformanc of ITER with Mixd B/gB modl is rlativly low (Fusion Q 3) compard to thos simulations using MMM95 modl (Fusion Q 1). It is worth noting that th BALDUR simulations using Mixd B/gB and MMM95 modls agr qually wll with prsnt-day xprimnts [13, 14]. In th ITER study using JETTO cod with Mixd B/gB modl [5], an optimistic prformanc of ITER was found (Fusion Q 16 with T pd 5 kv). An accss to scond stability of ballooning mod instability for th plasma dg was obtaind, and it was rsponsibl for an incras of th pdstal tmpratur and, consquntly, th cntral tmpratur, and th fusion prformanc. In Rfs. [9, 1], PTRANSP cod with GLF3 cor transport modl was usd to simulat ITER prformanc. A wid rang of prformanc was also found with th Fusion Q of A rcnt rport from th Intrnational Tokamak Physics Activity (ITPA) Profil Databas group using PTRANS and ASTRA cods to invstigat fusion prformanc in ITER was publishd in rfrnc [11]. It was found that in th ELMy H-mod scnario, a wid rang of Fusion Q was found (rangs from 5.5 to.1). Not that a pdstal tmpratur of 5.6 kv, prdictd using Sugihara modl [15], was usd in th PTRANS simulations whil th pdstal tmpratur of 1 kv was usd in ASTRA simulations. It can b concludd that a wid rang of fusion Q was obsrvd, with th minimum fusion Q obtaind blow th targt Fusion Q (Fusion Q of 1). Not that th ffcts of ITBs hav not bn includd in th simulations in th prvious studis. In Rf.[1], it showd that th prsnc of ITB can significantly improv th ITER prformanc. Bcaus th formation of ITB dpnds snsitivly on th E r B flow shar, it is consquntly important to xplor ITER scnarios with diffrnt forms of E r B flow shar. It is widly known that th prsnc of ITBs usually rsults in an improvd plasma prformanc, spcially nar cntral tmpratur and dnsity. In gnral, th prsnc of ITBs rsults in a paking of plasma profils in th ITB rgion. Th physics of ITBs can b found in Rf. [3]. 15

3 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 Thr ar svral modls attmpting to dscrib formation of ITBs [16-18]. An original Mixd B/gB modl was modifid to includ th ffct of ITBs by supprssion of anomalous cor transport using E r xb flow shar and magntic shar. This modl has bn succssfully rproducd in many xprimnts from larg tokamaks in various scnarios [17, 19-]. In this papr, a study of ITER simulations is prsntd that includs th ffcts of an ITB in th H-mod plasma. In gnral, a formation of dg transport barrirs (ETB) is a ky signatur of H-mod plasma, which is rsponsibl for improvd proprtis of H-mod plasma. In this work, th ETB is dscribd in trms of a pdstal modl basd on magntic and flow shar stabilization width scaling and a prssur gradint by a ballooning mod instability critrion [3]. In simulations of dischargs that contain an ITB, th ITB is formd by th supprssion of cor anomalous transport by th influnc of E r B flow shar and magntic shar. In this work, th E r B flow shar is obtaind dirctly from ithr JET discharg 454 or JET discharg This papr is organizd as follows: brif dscriptions of rlvant componnts of th BALDUR cod, th anomalous transport modl, and th pdstal modl ar prsntd in Sction ; prdictions of ITER prformanc using th BALDUR cod ar dscribd in Sction 3; and a summary is givn in Sction 4.. BALDUR Cod Th BALDUR intgratd prdictiv modling cod is usd to comput th tim volution of plasma profils including lctron and ion tmpraturs, dutrium and tritium dnsitis, hlium and impurity m dnsitis, magntic q (, whr m is th n toroidal rotation around th torus and n is th poloidal rotation around th torus), and dnsitis of nutrals and fast ions. Ths tim-volving profils ar computd in th BALDUR cod by combining th ffcts of many physical procsss slf-consistntly, including th ffcts of transport, plasma hating, particl influx, boundary conditions, th plasma quilibrium shap, and sawtooth oscillations. Fusion hating and hlium ash accumulation ar also computd slf-consistntly. BALDUR simulations hav bn intnsivly compard with a wid varity of plasma xprimntal data, which yild an ovrall agrmnt with about a 1% rlativ RMS dviation [13, 14]. In th BALDUR cod, fusion hating powr is dtrmind by th nuclar raction rats togthr with a Fokkr Planck packag usd to comput th slowing down spctrum of fast alpha particls on ach flux surfac in th plasma. Th fusion hating componnt of th BALDUR cod also computs th rat of th production of thrmal hlium ions and th rat of th dpltion of dutrium and tritium ions within th plasma cor. Th ffct of sawtooth oscillation is takn into account using th Porclli sawtooth modl [4] to triggr sawtooth crashs and a modifid Kadomtsv magntic rconnction modl [5] to dscrib th ffcts of ach sawtooth crash..1 Modl for ITB In this work, an ITB is formd by th supprssion of cor anomalous transport du to ExB flow shar and magntic shar. This ffct is includd in th Mixd Bohm/gyro-Bohm (Mixd B/gB) anomalous cor transport modl [6]. It was originally a local transport modl with Bohm scaling. A transport modl is said to hav Bohm scaling whn th transport diffusivitis ar proportional to th gyroradius tims thrmal vlocity. Transport diffusivitis in modls with Bohm scaling ar also functions of th profil shaps (charactrizd by normalizd gradints) and othr plasma paramtrs such as magntic q. Ths paramtrs ar hld fixd in 16

4 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 systmatic scans in which only th gyroradius is changd rlativ to plasma dimnsions. Th original modl was subsquntly xtndd to dscrib ion transport, and a gyro-bohm trm was addd in ordr to produc simulation rsults that match data from smallr tokamaks as wll as data from largr machins. A transport modl is said to hav gyro-bohm scaling whn th transport diffusivitis ar proportional to th squar of th gyro-radius tims thrmal vlocity dividd by a plasma linar dimnsion, such as th major radius. Th Bohm contribution to th original modl usually dominats ovr most of th plasma. Th gyro-bohm contribution usually maks its largst contribution in th dp cor of th plasma, and it plays a significant rol only in smallr tokamaks with rlativly low hating powr and low magntic fild. To includ th ITB ffct, th Bohm contribution is modifid by a cutoff that is a function of magntic and flow shar. Th Bohm/gyro-Bohm transport modl with ITB ffct includd [17] can b xprssd as follows: 1.. whr gb i gb.5 4. gb D H D Z B 5 6 T nt R n B T B B B T q i,.8 T T,1. i, EB.14 s ITG In ths xprssions, is th lctron diffusivity, i is th ion diffusivity, D H is th particl diffusivity, D z is th impurity diffusivity, gb is th gyro-bohm contribution, B is th Bohm contribution, is normalizd minor radius, T is th local lctron tmpratur in kv, B T is th toroidal magntic fild, R is th major radius, n is th local lctron dnsity, q is th safty factor, s is th magntic shar [r (d q / dr ) / q], ExB is th E r xb flow shar, C ExB is th constant for E r xb flow shar ffct (in most of simulations, C ExB =1), and ITG is th ITG growth rat, stimatd as v ti /qr, in which v ti is th ion thrmal vlocity. Th rol of impurity transport is vry complicatd and crucial for burning plasma xprimnts, sinc it controls impurity bhaviour, such as hlium ash accumulation. Sinc th original Mixd B/gB modl dos not includ impurity transport, in this work, it is assumd that th impurity transport is qual to th particl transport. Not that most notations usd in this papr ar dscribd in Tabl 1. Tabl 1: Notation usd in this papr Symbol Unit Dscription Normalizd minor radius T kv Local lctron tmpratur R m Major radius a m Minor radius I p MA Plasma currnt B Tsla Toroidal magntic fild n, X1 local lctron dnsity m -3 q Safty factor s Magntic shar ExB s -1 E r xb flow shar ITG s -1 ITG growth rat T pd (kv) Pdstal tmpratur n pd m -3 Pdstal dnsity M AMU Hydrognic mass c Normalizd critical prssur gradint. Modl for ETB In th BALDUR cod, th outr 17

5 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 plasma boundary condition is st at th top of th pdstal. As a rsult, th cod rquirs a modl for both tmpratur and dnsity at th top of th pdstal. A simpl modl for stimating pdstal tmpratur has bn dvlopd by using th valus of pdstal width and pdstal prssur gradint [3]. In th prsnt work, th pdstal width () is stimatd using a magntic and flow shar stabilization concpt ( C w s ), and th pdstal gradint is stimatd using a first ballooning mod prssur gradint limit. Th ffcts of th bootstrap currnt and plasma gomtry ar also considrd. Th pdstal tmpratur taks th following form: B M c 4 TpdkV.33CW s, q R n pd,19 whr n pd,19 is th lctron dnsity at th top of th pdstal in units of 1 19 m -3. Th xprssion usd to comput th normalizd critical prssur gradint, c, and th calibration usd to dtrmin th constant C W (=.4) ar dscribd in Rf. [3]. In gnral, th pdstal dnsity (n pd ) in H-mod plasmas is a larg fraction of lin avrag dnsity (n l ). Hr th pdstal dnsity is takn to b: n. 71 pd n l basd on th modl mployd in Rf. [4]. 3. Rsults and Discussions Th BALDUR cod is usd to carry out simulations of ITER with th dsign paramtrs for full-currnt standard typ I ELMy H-mod dischargs (R = 6. m, a =. m, I p = 15 MA, B T = 5.3 T, 95 = 1.7, 95 =.33 and n l = 1.x1 m -3 ). In th simulations, th plasma currnt and dnsity ar slowly rampd up to th targt valus within th first 1 sconds of th simulation, shown in Fig 1. Th plasma currnt during th startup phas is initially 3 MA and is slowly incrasd at th rat of.1 MA/sc to th targt currnt. It is found, using th pdstal modul [7], that th plasma maks a transition to th H- 18 mod phas at 4 sc during this startup ramp. In this work, th thrshold for th transition from L-mod to H-mod occurs whn th plasma hating powr xcds th following mpirical xprssion for th thrshold powr, takn from []: PL H MW.84M AMUB n, R a. It is worth noting that thr ar svral physical procsss that hav not bn includd in ths simulations, such as ELM crashs and noclassical taring mods. Consquntly, th simulation rsults do not rprsnt th complt dynamic bhavior of th ITER plasma. Howvr, it is xpctd that ths simulations includ nough physics to dscrib th plasma, whn it rachs a quasi-stady stat with sawtooth oscillations. Th simulations yild complx and intrsting intractions within th plasma itslf such as th slf hating of th plasma by th production of fast alpha particls and rdistribution of hating powr aftr ach sawtooth crash. Sawtooth oscillations ar considrd during th simulations. For ach simulation, th cor transport is a combination of anomalous transport and noclassical transport. An anomalous transport is calculatd using th Mixd B/gB transport modl with th ffct of ITB includd, whil noclassical transport is computd using th NCLASS modul [8]. Th boundary conditions ar providd at th top of th pdstal by th pdstal modl. In many xprimnts, it was found that ion pdstal tmpratur tnds to b highr than lctron pdstal tmpratur, spcially in low dnsity plasma. Sinc th ITER plasma is a high dnsity plasma, and consquntly, with high collisionality, th ion pdstal tmpratur should not b much diffrnt from th lctron pdstal tmpratur. For simplicity, it is assumd in this work that th lctron and ion pdstal tmpraturs hav th sam valus. Not that this assumption for th ion and lctron pdstal tmpraturs was mployd in th BALDUR cod to carry out th H-mod

6 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 simulations for prsnt day xprimnts, in which th agrmnt btwn simulations and xprimnts was in th rang of 1% RMS dviation [13, 14]. In ths simulations, th total auxiliary hating powr is 4 MW, which is composd of a combination of 33 MW NBI hating powr togthr with 7 MW of RF hating powr. During th slow currnt ramp, th plasma dnsity is also rampd up to th final plasma dnsity whil th full hating powr is applid, starting from th bginning of th simulation. During this ramp, th plasma maks an automatic transition from L-mod to H-mod, which is considrd by th powr thrshold modl []. Sinc thr is a strong hating arly in th simulations, all th simulations ntr th H-mod phas approximatly within 4 sc. In Fig. 1, th E r xb flow shar profils for optimizd magntic shar dischargs in th Joint Europan Torus (JET), dischargs 454 and 4847, ar shown. It can b sn that th E r xb flow shar profil from both dischargs ar diffrnt shaps, in which th main paks ar at =. and =.6 for JET discharg 454 and th main paks ar at =.3 and =.7 for JET discharg In addition, th magnitud of E r xb flow shar for JET discharg 454 is largr than that for JET discharg ExB (x1-5 s -1 ) Figur 1: Th E r xb flow shar profils for JET discharg 445 and 4847 ar plottd as a function of a normalizd minor radius. In Fig., th simulatd profils for ion tmpratur, lctron tmpratur, and lctron dnsity in ITER ar shown as a function of normalizd minor radius at a tim bfor a sawtooth crash. Ths rsults ar shown for simulations that ar carrid out using th Mixd B/gB modl with th ffcts of ITB xcludd and includd. It can b sn that whn ITB ffcts ar includd, th tmpratur in th rgion clos to th plasma cntr incrass, whil th tmpratur nar th dg rmains almost unchangd. Th incras of tmpratur in th simulation with E r xb flow shar obtaind from JET discharg 454 is largr than that from JET discharg This incras of tmpratur rsults from th strongr tmpratur gradint in th rgion clos to th plasma cntr. In Fig. 3, th profils from th plasma cntr up to =.8 of ion thrmal transports from simulations whn th ITB ffcts ar includd or xcludd ar shown. It can b sn that ion thrmal transport in th rgion clos to th plasma cntr in th simulations with th ITB ffcts includd ar svral tims smallr than that with th ITB ffct xcludd. This rduction of ion thrmal transport rsults in a strongr tmpratur gradint in th rgion clos to th plasma cntr, and consquntly, an incras of cntral ion tmpratur. It can also b sn that th ITB ffctiv rgion xtnds to a plasma radius of up to =.6 in th simulation using E r xb flow shar obtaind from JET discharg 454, and up to =.3 in th simulation using E r xb flow shar obtaind from JET discharg Th width of ITB ffctiv rgion is associatd with th location of th main paks of E r xb flow shar profil in Fig.. In addition, it can b sn that th tmpratur gradint in th ITB ffctiv rgion in th simulation using E r xb flow shar obtaind from JET discharg 454 is highr than that from JET discharg 454. All in all, it can b concludd that th ITB rgion in th simulation using E r xb flow shar obtaind 19

7 Elctron tmpratur (kv) Ion tmpratur (kv) Elctron Dnsity (x1 19 m -3 ) Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 from JET discharg 454 has a largr ITB rgion and strongr tmpratur in th ITB rgion. This is not surprising sinc th E r xb flow shar profil obtaind from JET discharg 454 is highr than that from JET discharg It is also found that th pdstal boundary condition rmains almost constant aftr th dnsity rachs its targt valu. Not that th ion pdstal tmpratur is assumd to b th sam as th lctron pdstal tmpratur in this modl. Also, th ffcts of ELMs hav not bn includd in ths simulations. For th lctron dnsity, th cor profil is narly flat, with rlativly limitd cntral paking. Whn an ITB is includd, th cntral dnsity profils from both simulations rmain narly unchangd ITB Excludd ITB Includd (454) ITB Includd (4847) Figur : Profils for ion tmpratur and lctron tmpratur and lctron dnsity ar plottd as a function of a normalizd minor radius at th tim bfor a sawtooth crash. Th simulations ar carrid out with and without ITB ffcts. Summaris of th avrag plasma paramtrs prdictd by ths simulations ar shown in Tabl. It can b sn that th cntral ion tmpratur incrass whn th ITB ffcts ar includd. Th avrag cntral ion tmpratur in th ITB simulation with E r xb flow shar obtaind from JET discharg 454 is about 31. kv, which is in th ffctiv rang for nuclar fusion powr production. Th cntral ion tmpraturs incras by 16% and % in th simulations with th ITB ffcts includd using E r xb flow shar obtaind from JET discharg 454 and JET discharg 4847, rspctivly. This incras of cntral tmpratur has a strong impact on th total plasma stord nrgy and th nuclar fusion powr production

8 Elctron tmpratur (kv) Elctron tmpratur (kv) Ion thrmal transport (m /s) Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr ITB xcludd ITB includd (454) ITB includd (4847) Figur 3: Th profil of total ion diffusivity is plottd as a function of normalizd minor radius at tim of 1 sc. Th simulations ar carrid out with and without ITB ffcts. Th plasma stord nrgy is shown as a function of tim btwn 9 to 1 sc in Fig. 4. It can b sn that th plasma stord nrgy is in th rang of 1 MJ for th simulation with no ITB, whil th plasma stord nrgy incrass to MJ in simulations with th ITB ffcts includd, using E r xb flow shar obtaind from JET discharg 4847, and incrass to 43 MJ in simulations with th ITB ffcts includd, using E r xb flow shar obtaind from JET discharg 454. Th tim-dpndnc of th alpha powr dposition is shown in Fig. 5 from th simulations with ITB ffcts xcludd and includd. It can b sn that th alpha powr from th simulation with ITB ffcts includd by using E r xb flow shar obtaind from JET discharg 454 is much highr than that without an ITB, whil th alpha powr from th simulation with ITB ffcts includd by using E r xb flow shar obtaind from JET discharg 4847 is slightly highr than that without an ITB. Th avrag of plasma stord nrgy and alpha powr during th tim btwn 9 sc and 1 sc ar summarizd in Tabl. Th fusion prformanc can b valuatd in trm of th fusion Q, which can b calculatd as 5 P Fusion Q P, avg AUX, whr P,avg is a tim-avrag of th alpha powr and P AUX is th auxiliary hating powr (qual to 4 MW for ths simulations). It can b sn in Tabl that th fusion Q incrass by 4% and % whn ITB ffcts ar includd using E r xb flow shar obtaind from JET discharg 454 and 4847, rspctivly ITB xcludd ITB includd (454) ITB includd (4847) Figur 4: Th plasma stord nrgy is plottd as a function of tim for simulations with ITB ffcts xcludd and includd. 1 ITB xcludd ITB includd (454) ITB includd (4847) Figur 5: Th alpha powr production is plottd as a function of tim for th simulation whn an ITB is includd and xcludd. 1

9 Ion tmpratur (kv) Ion tmpratur (kv) Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 Tabl : Summary of plasma paramtrs during last 1 sc of ach simulation (from 9 sc to 1 sc). Paramtrs Unit ITB ITB includd xcludd T i, kv T, kv n, 1 19 m T pd kv n,pd 1 19 m W tot MJ P, avg MW Fusion Q In Fig. 6, th ion tmpratur profils ar plottd as a function of normalizd minor radius for th simulation with ITB ffcts includd by using E r xb flow shar obtaind from JET discharg 454 and This figur aims to show th influnc of E r xb flow shar s magnitud on th prdiction. It can b sn that whn th valus of C ExB incrass, th ion tmpratur, as wll as th lctron tmpratur, in th ITB ffctiv rgion incrass. In th simulations using E r xb flow shar obtaind from JET discharg 454, th ITB ffctiv rgion ar th sam (up to =.6). On th othr hand, in th simulations using E r xb flow shar obtaind from JET discharg 4847 with C ExB qualing.5 and 1., th ITB ffctiv rgion ar th sam (up to =.3). Howvr, whn C ExB incrass to 1.5, th ITB ffctiv rgion xpands clos to =.6. In Tabls 3 and 4, summaris of th avrag stord nrgy, alpha powr, and fusion Q prdictd by ths simulations ar shown. It can b sn that thos paramtrs incras with th incrasing of C ExB. Tabl 3: Summary of plasma paramtrs during last 1 sc (from 9 sc to 1 sc) of ach simulation using E r xb flow shar obtaind from JET discharg 454 with diffrnt valus of C ExB. Paramtrs Unit 454 C ExB=.5 C ExB=1. C ExB=1.5 W tot MJ P, avg MW Fusion Q Tabl 4: Summary of plasma paramtrs during last 1 sc (from 9 sc to 1 sc) of ach simulation using E r xb flow shar obtaind from JET discharg 4847 with diffrnt valus of C ExB. Paramtrs Unit 4847 C ExB=.5 C ExB=1. C ExB=1.5 W tot MJ P, avg MW Fusion Q C_ExB=.5 C_ExB=1. C_ExB= Figur 6: Th ion tmpratur profils ar plottd as a function of normalizd minor radius at th tim bfor a sawtooth crash for diffrnt valus of C ExB. Th simulations using ExB from JET discharg 454 (top) and using ExB from JET discharg 4847 (bottom) indicat an improvmnt dpnding on valus of C ExB. 4. Conclusions Slf-consistnt modling of th ITER tokamak has bn carrid out using th BALDUR cod. Th outr plasma boundary in ths simulations is takn to b at th top of th pdstal, whr th pdstal tmpraturs and dnsity ar computd

10 Thammasat Int. J. Sc. Tch., Vol. 14, No. 3, July-Sptmbr 9 using a thory-basd pdstal modl. Th pdstal tmpratur modl is basd on magntic and flow shar stabilization of transport togthr with th first stability rgim of a ballooning mod limit. Th pdstal tmpratur modl is usd togthr with a Mixd B/gB cor transport modl, which can includ th ffcts of ITBs. It is found that th formation of ITBs has a strong impact on both lctron and ion tmpratur profils, spcially nar th cntr of th plasma; whil only small impact is found on th lctron dnsity. Whn th ffct of an ITB is not includd, th prdictd cntral ion tmpratur is just abov 1 kv. With an ITB includd in th simulation, th cntral ion tmpratur can significantly incras up to th rang of 3 kv, dpnding of th dtails of E r B flow shar profil. Th incras of cntral tmpratur rsults in a significant improvmnt in th alpha powr production and, consquntly, th fusion prformanc. It is obsrvd that th thrmal and particl diffusivitis in most of th plasma cor ar smallr in th simulations with an ITB includd than in thos without th ITB. This rduction in th diffusivity rsults in strongr gradints and, consquntly, highr valus of th cntral tmpratur and dnsity. 5. Acknowldgmnts Th author xtnds thanks to Prof. Dr. A H Kritz, Dr. G Batman, Dr. V Parail, Dr. A Pankin, Dr. S Suwanna, Dr. N Poolyarat, and Dr. R Picha for hlpful discussions and support. This work is supportd by Commission on Highr Education (CHE) and th Thailand Rsarch Fund (TRF) undr Contract No. RMU Rfrncs [1] Hubbard A, Physics and Scaling of th H-mod Pdstal, Plasma Phys. Control. Fusion, 4 A15,. [] Aymar R, Barabaschi P, Shimomura Y, Th ITER Dsign, Plasma Phys. Control. Fusion, 44519,. [3] Connor J W, Fukuda T, Garbt X, t al., A Rviw of Intrnal Transport Barrir, Physics for Stady-Stat Opration of Tokamaks, Nucl. Fusion, 44 R1, 4. [4] Batman G, Onjun T, Kritz AH, Intgratd Prdictiv Modlling Simulations of Burning Plasma Exprimnt Dsigns, Plasma Phys. Control. Fusion, , 3. [5] Onjun T, Batman G, Kritz AH, t al.,magntohydrodynamic-calibratd Edg-Localizd Mod Modl in Simulations of Intrnational Thrmonuclar Exprimntal Ractor, Physics of Plasmas, , 5. [6] Onjun, T, Tharasrisuthi K, Pankin AY, t al., Projctd Prformanc of ITER Basd on Diffrnt Thortical Basd Pdstal Tmpratur Modls, J. of Physics: Confrnc Sris, , 8. [7] Tharasrisuthi K, Onjun T, Onjun O, Projctions of ITER Prformanc Basd on Diffrnt Pdstal Tmpratur Scalings, Thammasat Intrnational Journal of Scinc and Tch., 13 45, 8. [8] Picha R, Onjun T Tharasrisuthi K, t al., Dpndnc of ITER Prformanc on Pdstal Tmpratur, Avrag Elctron Dnsity, Auxiliary Hating Powr, and Impurity Contnt, in Proc. 35th EPS Conf on Plasma Physics, Hrsonissos 9-13 Jun 8 [9] Halprn FD, Kritz AH, Batman G, t al., ( Prdictiv Simulations of ITER Including Nutral Bam Drivn Toroidal Rotation, Phys. Plasmas, , 8. [1] Budny RV, Andr R, Batman G, t al., Prdictions of H-mod Prformanc in ITER, Nucl. Fusion , 8. 3

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