Accuracy of TEXTOR He-beam diagnostics

Transcription

1 Accuracy of TEXTOR He-beam diagostics O. Schmitz, I.L.Beigma *, L.A. Vaishtei *, A. Pospieszczyk, B. Schweer, M. Krychoviak, U. Samm ad the TEXTOR team Forschugszetrum Jülich,, Jülich, Germay *Lebedev Physical Istitut, Moscow, RF Itroductio stadard He-beam diagostics o TEXTOR Atomic processes ivolved Evaluatio procedures Atomic data Results - stadard, ew - compariso of itesity profile fits compariso for differet atomic data compariso for differet discharge coditios compariso of differet diagostics Summary & coclusios

2 Stadard TEXTOR He-beam diagostics imagig fibre guide image itesifier Li chael He chaels iterferece filters photo objectives f=25mm ijectio system lier ALTlimiter lie emissio collisios ijected He & Li atoms vacuum vessel i / 1 costat relaxatio time τ r sufficietly small temporal resolutio: t=τ r (max) spatial resolutio: x = t v Strahl o p & d collisios 18-3 /10 m e T/eV e liie itesity ratios: siglet : siglet I(668m) / I(728m) e depedet siglet : triplet I(728m) / I(706m) T e depedet M.Brix (2000)

3 bdx d i = Trilateral Euregio Cluster pop. processes + σ e,jiv j,j i Atomic processes e + σ p,jiv ioj j,j i + A j depop.processes σ e,ij v i,j i σ p,ijv i,j i ji j j, j> i j, j< i e A ij i iois, i io i σ v σ v σ p cx, i iois, i v io e i e io i i i electro collisio excitatio io collisio excitatio spotaeous emissio electro collisio ioisatio io collisio ioisatio charge exchage

4 Evaluatio procedures For kow T e (r) ad e (r) -> lie itesity profiles I ( r) = λ k A ki I ( r) = k A ki However, we eed for kow -> T e (r) ad e (r) λ M. Brosda ad M.Brix have already show that it is possible to restore T e ad e profiles from lie profiles I 1 (r); I 2 (r); I 3 (r) Possible approaches: o-statioary (NS): direct solutio of the geeral (time / space) depedet equatio ad fit I (r) = A to the measured oe. quasi-statioary (QS): approx. solutio of the NS equatios: o the right the St-solutio of the balace equatios for rel. populatios k / 1 of the excited states is iserted. λ k ki statioary (St): the derivatives are eglected assumig that the time costat of the measured processes are larger tha the relaxatio times τ for the trasitios used.

5 Atomic data - levels The followig atomic levels of He I have bee icluded i the model: (1): 1s 2 1 S; 1sl 1 L; 1sl 3 L; = 2; 3; 4, l = 0; 1; 2 (1i):1s4f 1 F; 3 F (2): 1s_1 (siglets), 1s_3 (triplets), = 5; 6; 7 summed over all l (3): 1s; = 8; 9 summed over all l ad S (c): c = 1s groud state of He II "effective" levels have bee itroduced, which describe group of levels summed over some quatum umbers (decreases drastically the dimesios of the statistical matrix). group (1): SL couplig is a good approximatio. group (1i) ad ay levels with l > 2: deviatio from the SL couplig is sigificat. The matrix of the eige-vectors i itermediate couplig was obtaied for the states (1i) usig the GRASP92-code (Drake). For the levels 1s; = 8; 9 summed over all l ad S the type of couplig is ot importat. For the levels 1s_1 (siglets), 1s_3 (triplets), = 5; 6; 7 a effective mixig due to deviatio from the SL couplig was itroduced.

6 Atomic data eergies, radiatio, collisio with e The followig atomic levels of He I have bee icluded i the model: (1): 1s 2 1 S; 1sl 1 L; 1sl 3 L; = 2; 3; 4, l = 0; 1; 2 (1i):1s4f 1 F; 3 F (2): 1s_1 (siglets), 1s_3 (triplets), = 5; 6; 7 summed over all l (3): 1s; = 8; 9 summed over all l ad S (c): c = 1s groud state of He II Eergy levels: from NIST A for 1s2p 1,3 P 1s 2 1 S from Wiese (NSRDS-N.B.S.) A for groups (1), (1i) from ATOM, itermediate couplig for 1s4f 1s3d, SL for others A for trasitios iside ad betwee groups (2), (3): Kramers formula <σv> ex for group (1): CCC-89 cross sectios (Bray) <σv> ex from group (1) to groups (1i),(2),(3),c: ATOM code (Norm.BA) <σv> ex iside groups (1),(2),(3): semiclassical method (Beigma) trasitios to group (1i): itermediate couplig

7 Atomic data collisios with p,d, CEX The followig atomic levels of He I have bee icluded i the model: (1): 1s 2 1 S; 1sl 1 L; 1sl 3 L; = 2; 3; 4, l = 0; 1; 2 (1i):1s4f 1 F; 3 F (2): 1s_1 (siglets), 1s_3 (triplets), = 5; 6; 7 summed over all l (3): 1s; = 8; 9 summed over all l ad S (c): c = 1s groud state of He II Collisios with heavy particles at thermal eergies may oly cotribute for trasitios with = 0 <σv> p, d for the most importat 3l 3l : from CC-method (code ATCC (Borodi)) for all other trasitios: Norm. Bor approximatio (Borodi) <σv> CEX from the metastable state 1s2s from code CAPT (Shevelko) with cross sectios for 4 from (Jaev) Normalized Bor Approximatio Close couplig method

8 Results Compariso of differet models ST w/o p ST w p Ti =T e STs ST w/o p ST w p T i =T e ST w p T i =2T e ST w p T i =2T e STs proto collisios do ot seem to play a strog role some effect is of course expected at high desities T i effects are still weak

9 Results T e & e diagram (ew) ST w/o p ST w p T i =T e ST w p T i =2T e /10 m e evaluatio rages could be exteded proto collisios reduce the electro desities icrease the electro temperatures 0 0 T/eV e

10 Results Compariso for itesity profile fits (Ohmic discharge) (# 96705) 667m 706m 728m NS for large radii: τ r is too large ST STs for small radii: stroger impact of higher l-mixig (ot yet cosidered)

11 Results Compariso for Ohmic discharges (# 98026) NS ST STs for large radii: τ r is too large for small radii: stroger impact of higher l-mixig (ot yet cosidered) For Ohmic discharges: The deviatio betwee Brix's CRM ad the ew oe accouts to 10% for T e ad is egligible for e. The impact of proto collisios as well as of the ew atomic processes (CXRS ad a ew ioisatio rate coefficiet) seems to have a mior effect.

12 esults Compariso for itesity profile fits (small NBI-heatig) (# 95907, 300kW) 667m 706m 728m T e & e strog deviatios (especially for T e ) ST STs NS for all models at small radii Ifluece from higher levels!?

13 Results discharges with small NB-heatig (# 95896, 300kW) ST NS STs T e & e much better coicidece ow

14 Results discharges with strog NB-heatig (# 96710, 1200kW) NS ST STs T e & e agai much better coicidece ow, NS allows extesio ito the cofied plasma

15 Results compariso with differet diagostics e He- & Li-beam data extrapolate well ito the HCN data TS seems too small (calibratio error?) Zoom T e He-data extrapolate well ito the HCN & TS data

16 Summary & Coclusio A exteded model (to Brix 2000) with proto collisios ad CEX processes has bee tested o TEXTOR discharges. Oly margial deviatios => impact of the proto collisios is weak uder the target plasma coditios ivestigated. Evaluatio with the o-statioary approach (NS) ehaces the radial extesio of the profile ad cacels relaxatio pheomea. A method to apply the NS method as stadard evaluatio is uder developmet. For the measuremet errors the rage of T e = 30% ad e = 10% give by Brix 2000 is still valid. Proto collisios (witht i =T e ) do ot exceed these margis. Compariso of the e (r) ad T e (r) profiles obtaied with other edge are i reasoable agreemet with those from He. BES o thermal He should be a reliable method for measuremets withi m -3 < e < m -3 ad 20 ev < T e < 300eV.