L-mode DB 2.7: new contributions from FT/FTU and some analysis

Transcription

1 Confinement Database and Modelling Meeting 2-5 April, Lausanne L-mode DB 2.7: new contributions from FT/FTU and some analysis G. Bracco Associazione Euratom-ENEA sulla Fusione, Frascati

2 Outline L mode DB vs 2.7, released 26/3/2001 L mode regressions, B t dependence Saturated OH confinement analysis New FT/FTU contribution (FT Hydrogen data) FTU data with pellet injection Conclusions

3 L mode DB version 2.7 TOKAMAK N DB23a BMIN BMAX H D HE3 HE4 M=1.5 ALCC ASDEX CMOD D3D DIII FT FTU JET JFT2M JT PBXM PDX RTP START T TDEV TEXTOR TFTR TSUPRA Tot: 8706 data new data since version 2.3a: ALCC, ASDEX, FT, FTU, JET, RTP, T10, TSUPRA A preliminary version 3.0 was presented at Frascati meeting Sept 2000; This version 2.7 contains the results of some clean-up work

4 L mode DB version 2.7: MEFF & PHASE (1) D TOKAMAK N BMIN BMAX OH L I EP ALCC ASDEX CMOD D3D DIII FT FTU JET JFT2M PBXM START T TDEV TEXTOR TFTR TSUPRA

5 L mode DB version 2.7: MEFF & PHASE (2) H TOKAMAK N BMIN BMAX OH L ALCC ASDEX CMOD D3D FT FTU JET JFT2M JT PDX RTP TFTR TSUPRA HE3 TOKAMAK NBMINBMAXOH L JET LHEP EP M=1.5 TOKAMAK NBMINBMAXOH L LHEP EP JET HE4 TOKAMAK NBMINBMAXOH L LHEP EP D3D JET JFT2M TSUPRA

6 L mode: regression for data in DB2.3a 1498 data τ freefit =0.022 I 0.93 B 0.06 P n 0.41 M 0.19 R 1.81 ε k 0.69 RMSE=0.155 τ L96P(th) =0.023 I 0.96 B 0.03 P n 0.40 M 0.2 R 1.83 ε k 0.64 Free fit: by changing the R exponent to 1.84 the high-β constr. is fulfilled; The high-β constrained fit is practically the same Bohm ρ* dependence. Result very similar to ITERL96P(th) Selection criteria: ISELDB2=11 H, D, PHASE=L, BEILI2<2

7 L mode: constrained regression including new data τ constr =0.022 I 0.89 B 0.09 P n 0.42 M 0.22 R 1.88 ε k 0.71 RMSE=0.156 τ L96P(th) =0.023 I 0.96 B 0.03 P n 0.40 M 0.2 R 1.83 ε k data from 14 tokamaks new tokamaks FTU, RTP, T10 more data from TSUPRA The free fit is practically the same Bohm ρ* dependence. Result very similar to ITERL96P(th) Selection criteria: H, D, PHASE=L, BEILI2<2

8 L mode: TAUTH/Constr.regression versus B τ constr =0.022 I 0.89 B 0.09 P n 0.42 M 0.22 R 1.88 ε k 0.71 TAUTH/ τ constr Very weak magnetic field dependence in the scaling; no systematic trend. Bohm ρ* dependence. Result very similar to ITERL96P(th) B (T)

9 OHMIC Section Originally the OH section was composed only reference data for the additionally heated phase. Now OH data in L mode DB are the largest subset (6208 data over 8706). extended contributions: ALCC, ASDEX,CMOD,FT, FTU, JET, JT60 no data: D3D,DIII,JFT2M,PBXM,TFTR PDX,RTP,START,T10,TDEV,TEXTOR,TSUPRA few data: START: old data (higher values reported e.g. Varenna TTF 2000) TEXTOR: strange LOC data TSUPRA: SOC data? t 0.25 s (0.35 s reported in literature) PDX,RTP,T10,TDEV: SOC data? Some relevant quantities for OH confinement analysis are missing: ZEFF,TEV,TE0 (ALCC,CMOD), QEDGE(START,JT60)

10 OH: SOC regression A regression of the data in the Saturated OH Confinement regime (H,D, no pellet) has been performed: QEDGE has been defined for START (low aspect ratio formula) and JT60 (usual formula) SOC data selection 2 criteria: (1) critical density between LOC/SOC from Shimomura scaling : n 19 > 6.5 M 0.5 B/qR (2) τ neoa =0.007aR 2 k n 19 q >MIN defined ad-hoc for each tokamak NOH N (1) N (2) MIN ALCC ASDEX CMOD FT FTU JET JT PDX RTP 8 1 START T10 8 TDEV 3 TEXTOR TSUPRA

11 SOC Regression (1) MEFF RGEO eps KAPPA nel19 bt ipma RMSE ITER Freefit (s) (1) (1) (2) (2) Constrained (1) (2) ITER-FEAT τ SOC =0.03 B 0.6 R 2 ε 0.5 M 0.2 k τ SOC =0.09 B 0.6 R 2 ε τ SOC =0.05 B R 2 ε M 0.5 k 0.5 ZUO, EPS1995,TORE SUPRA NeoAlcator at n 19 =6.5 M 0.5 B/qR (ITER Physics Basis)

12 SOC Regression (2) τ SOC =0.03 B 0.6 R 2 ε 0.5 M 0.2 k τ SOC =0.05 B R 2 ε M 0.5 k 0.5 NeoAlcator at n 19 =6.5 M 0.5 B/qR [SOC data selected by the criteria τ neoa =0.007aR 2 k n 19 q >MIN(TOK)]

13 SOC Regression (3): B dependence TAUTH/τ SOC TAUTH/τSOC τ SOC =0.03 B 0.6 R 2 ε 0.5 M 0.2 k B freefit τ SOC =0.028 B 0.41 R 2.01 ε 0.33 M 0.26 k 1.04 A weak trend with B is observed with the constrained fit [SOC data selected by the criteria τ neoa =0.007aR 2 k n 19 q >MIN(TOK)] B

14 Pellet injection in OH plasma: ALCC, FTU FTU TAUTH NeoAlc TAUTH/τ SOC ALCC TAUTH NeoAlc B Energy confinement time can increase up to a factor 2 compared to SOC values with pellet injection

15 Conclusions L mode DB version 2.7 is in a better shape compared to the last meeting in Frascati, Oct.2000 L mode data regression confirms the results summarized by scaling ITERL96p(th) A scaling for saturated ohmic confinement has been obtained.