Capabilities of the ITER Electron Cyclotron Equatorial Launcher for Heating and Current Drive

Transcription

1 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Capabilities of the ITER Electron Cyclotron Equatorial Launcher for Heating and Current Drive Daniela Farina L Figini, M Henderson, G. Ramponi, and G Saibene Istituto di Fisica del Plasma, CNR, EURATOM-ENEA Association, Milano, Italy ITER Organization, Saint-Paul-lez-Durance France Fusion for Energy, Barcelona, Spain acknowledgments A. Loarte, T. Casper, K. Kajiwara, K Takahashi EC-17, Deurne 1.5.1

2 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Outline ITER Equatorial Launcher (EL) goals EC capabilities within present EL design ECCD in scenarios at full field ECCD in plasma current ramp-up full field nominal and reduced B field Proposal of a new EL design with poloidal steering mirrors work done under ITER Contracts see Farina et al NF 1 D Farina, EC

3 !"#$#%#&'.$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, ITER EL design and physics goals ITER Equatorial Launcher (EL) 17 MW Present design (still to be finalized) 3 sets of 8 beams, equatorial port 3 mirrors same different z, TOP, MID, BOTTOM Toroidal steering Physics Objectives Access in range of ρt<.5) Drive Current (co-eccd) Current Profile tailoring (co&cnt-eccd) Central Heating Assist L-H transition SS operation Breakdown & Burnthrough D Farina, EC

4 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Beam tracing analysis! Beam tracing code GRAY (Farina, FS&T 7): astigmatic Gaussian beam propagation relativistic power absorption (Farina, FS&T 8) ECCD moment conservation model (Maruschenko FS&T 9) J and p d profile characterization almost Gaussian profile: ρ tor, Δρ tor : peak radius, profile width at 1/e generic profiles: < " >= <ρ>, σ ρ =(<δρ >) 1/ : average radius and width # # " p(")dv p(")dv Launching set up = # # " dp dp 3 mirror locations (beam / single ray analysis)! < "# >= R=96.5 cm z=, 6, 1 cm poloidal α and toroidal β launching angles tanα=n z /N R, sinβ=n φ % (#$ < # >) p(#)dv % p(#)dv dp/dv (MW/m 3 )..1 dp/dv (MW/m 3 ) OM B =5.3T peak! tor XM B =.65T peak! tor! "! tor ! average <!> º β 5º α =º, ± 5º D Farina, EC

5 !"#$#%#&'.$,1&'+-($1&-+ ITER Scenarios for ECRH&CD analysis!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, (a) 15 MA Two main ITER scenarios at full field (ITER IDM): a) 15 MA Elmy H-mode Scenario 1st harm nd harm Low Te & high ne ->low ECCD efficiency b) 9 MA non inductive Scenario - High Te & low ne -> high ECCD efficiency β=º, ~15% nd harm. abs (b) 9 MA e e 8 6 e n 1 9 MA 15 MA. e T 1 e e T (kev) n T n (119 m-3) 3 1st harm nd harm Raxis shifted outward -.! β=º, up to 6% - nd harm. abs.` D Farina, EC

6 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, ECCD results at full field II cd I/P (ka/mw) 3 1 MID LOW TOP 15 MA (b) SCEN 15 MA: ~15% larger I cd wrt old scen. estimates (momentum conservation model) II cd I/P (ka/mw) MID! J LOW ! J TOP 9 MA (b) SCEN 9 MA: quite large I cd, up to 6 ka/mw up to +5% more than for previous scen. (larger T e ) dotted lines: non monotonic J profile ( nd harm contribution) Achievable radial range : < ρ <.5 D Farina, EC

7 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, ECCD profiles The present EL design foresees co-injection from TOP and LOW rows and counter injection from MID row. Various H&CD combinations are feasible delivering power either to a single row or to more than one row in different directions. LIMITATION upper radial limit around ρ.5 OPEN ISSUE How to further optimize EC interaction region? Current density profiles D Farina, EC

8 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, EC potential at various time slices time slices of a 15 MA Scenario (courtesy T Casper, ITER): a) after diverting (L-mode) b) during current ramp-up (L-mode) c) at the end of current ramp-up (H-mode) d) at an early burn stage (H-mode) t=11 s t=58 s t=8, 13 s case time slice I pl (MA) n e (1 m -3 ) T e (kev) Fusion power (MW) (a) 11.7 s (b) 58 s (c) 8 s (d) 13 s D Farina, EC

9 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, ECCD in the ramp-up phase II cd I/P (ka/mw) II cd I/P (ka/mw) s LOW MID P abs >95% 8 s OM 58 s! J J XM TOP OM MID ROW XM 13 s OM t=11 (a) s t=13 s wide radial deposition range lower ECCD efficiency due to nd harm. parasitic absorption t=8 s OM absorption, large ECCD efficiency t=58 s both XM & OM absorption but at different location higher I cd for XM injection t=11 s XM absorption only, close to plasma center quite high I cd because of low n e D Farina, EC

10 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, XM absorption at low density (a) (b) XM1 interaction usually prevented in case of low field side injection due to presence of right cutoff - - ω p /ω = (1-N )(1- Ω/ω) (blue dotted line) (c) (d) At low n e and high T e, XM absorption may occur along the trajectory far ahead of the EC cold resonance (red line) in the upshifted resonance region at Ω(x)/ω =[1-N (x)] 1/ (red dashed line) Right cutoff shifts outwards for increasing n e (a->d) XM1 interaction cannot occur anymore after a given time depending on the injection angle D Farina, EC

11 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, EC heating capabilities at B 5.3 T radial power localization versus magnetic field for º β º and XM&OM injection, P abs >95% GOAL: Central Heating: Power absorbed inside ρ.5 L to H-mode: Heat inside separatrix ρ.85 OM efficient at large T e, n e (t=8s, 13s) high B (OM1) at B T: 1 st harm. at hfs boundary & nd harm. at lfs boundary XM efficient at low n e (t 58s) as XM1 at low B (XM-3) D Farina, EC

12 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Heating potential at lower B Maximum EC power deposited inside radius ρ t=58 s 1.8 P ins (ρ) = ρ p dv High EC absorption in a quite wide B range P ins /P (b).6.. ECRH efficient not only close to nominal and half values 5.3 T &.65 T t=13 s B (T) critical B intervals: 3.6 T <B < T : 1 st and nd harmonic are close to inner/outer plasma boundary P ins /P (d) B (T).6.. B <.5 T : EC interaction occurs at nd and 3 rd harmonic (less efficient, especially at low n e & T e ). maximum over OM&XM, and º β º D Farina, EC

13 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, How to extend EC deposition region? Driven EC current Full poloidal and toroidal angle scan 15 MA MID ROW 9 MA MID ROW poloidal toroidal toroidal steering toroidal D Farina, EC

14 !"#$#%#&'.$,1&'+-($1&-+ Which is the best path in α & β?!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, at present pure toroidal steering should we move to poloidal steering? or to a combination of the two? PROS and CONS in all options D Farina, EC

15 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, 3 EL How to maximize ECCD? º β 5º points: α= toroidal steer. toroidal steering I cd up to ρ.5 I cd (ka/mw) poloidal steering I cd at ρ>.5 I cd (ka/mw) º β 5º 18º β º 5º α 65º D Farina, EC ρ EL 18º β º 5º α 65º points: α= toroidal steer ρ UL UL EL poloidal steering allows to: maximize I cd at mid radius drive current beyond mid radius Constraint on the choice of the toroidal angle: β <~3º to allow for EC assisted breakdown and startup from EL CAVEAT Present analysis based on scenarios at burn, results sensitive to n&t values 15

16 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Toroidal versus poloidal steering TOP MID - BOTTOM I cd (ka/mw) MA β=º solid lines β=º dotted lines tor. steer. dots 15 MA Scenario: poloidal steering allows to extend radial deposition region I cd values almost the same as for toroidal steering I cd (ka/mw) ρ D Farina, EC ρ 9 MA β=º solid lines β=º dotted lines tor. steer. dots MA Scenario: much lower I cd at.<ρ<. ( nd harm. absorption at low beta) much wider radial interaction region in case of poloidal steering 16

17 .$,1&'+-($1&-+!"#$%&'%"()*+%"#*',(-,'',(.%/,/1, Conclusions Two reference ITER scenarios investigated with new CD momentum conservation model (+15% ECCD) ECH&CD during plasma ramp-up conditions at nominal magnetic, high to full absorption in spite of reduced n e and T e EC system applicable for central heating (inside mid radius) for the majority of the toroidal magnetic field range from half to full field Proposal for a poloidal steering EL setup to increase ECCD beyond mid radius, further investigation still required, final assessment in the near future D Farina, EC