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ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade

ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade. Reported by Jörg Stober for the AUG Team. Topics. selected results of the last campaign, related to IOS RMP-coils N 2 -seeding : high power, q 95 = 3 O1 heating of H-modes improved H-mode (advanced inductive)

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ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade

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  1. ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade Reported by Jörg Stober for the AUG Team

  2. Topics • selected results of the last campaign, related to IOS • RMP-coils • N2-seeding : high power, q95 = 3 • O1 heating of H-modes • improved H-mode (advanced inductive) • Issues related to JE, not reported elsewhere • 4.3 nu* scann: plans for next year • 5.2 ICRH • Next campaign: time line and hardware modifications

  3. RMP-coils (Next slides from W. Suttrop, ITPA-PEP) Operation Jan - Jul 2011: 2×4 B-coils (upper and lower rows) n = 2 ELM mitigation n = 1 Error field measurement Shutdown Aug-Dec 2011 Installation of additional 8 upper/lower B-coils Operation Jan 2012 - n = 0, odd/even up/down parity n = 2, row phasing 0,90,180,270 degrees n = 4, odd/even up/down parity Power supplies: — Currently 2 circuits with grid-commutated 2-quadrant converters fmax 20 Hz. — Seeking solution for 4 independent 4-quadrant amplifiers (±1 kA into 500 μH) (n = 3, rotating fields) Full in-vessel coil set: 3 rows, each with 8 saddle coils W Suttrop et al, Fus. Eng. Des. 84 (2009) 209

  4. RMP-coils : no ELMs triggered with pellet fuelling P. Lang

  5. RMP-coils : central densities of 1.6 nGW selected

  6. RMP-coils : no density dependence of E

  7. RMP-coils : DIII-D low-* mitigation not reproduced selected W.Suttrop, T.Evans

  8. RMP-coils : comparison with DIII-D ongoing selected

  9. RMP-coils : summary

  10. High power seeding with peak heatload < 5 MW/m2 Peak load < 5 MW/m2 ! Combined strong D divertor puff, feedback controlled N divertor seeding (q95=3.7, u=0.1, l=0.43) Modelling with B2-Eirene about to start IOS 1.2, A. Kallenbach

  11. q95 = 3 with N2 seeding #26870 Ptot TS PNBI, Prad Te PECRH,X3 snif N2 Ip (MA) D2 MP-coils N IR-Power Div o i H-factor Wmhd ne core Te,div edge

  12. X1 O1-heating of H-modes : polarisation control 105 GHz Bt= 3.2 T „wrong“ X-mode directly reflected O1 1st harm Res X-mode cut-off

  13. 10 5 Sniffer signal (V)  / 4 Power X-mode 4 8 1 7 0 4 % 6 3 1 6 0 2 % 4 2 1 5 0 5 0 6 0 7 0 8 0 2 1  / 8 Power X-mode (%) 0 1.5 2.0 2.5 time (s) 158 167 O1-heating of H-modes : polarisation control H-mode, 1 MA, -3.2 T, 105 GHz, #26864 With 1% X-mode content, switch-off level is already exceeded (preliminary, orthogonal scan still to be done)

  14. O1-heating of H-modes: effect of UHR V. Vdovin finds significant effect of UHR for O1 scenario with full wave code. Does he predict measurable effects for AUG ? These could be verified using modulated ECRH and X2-ECE. Preparation on AUG: finalize polarisation control such that X2-ECE can be used (up to 188 GHz) AUG-proposal submitted for 2012 co-authors: V. Vdovin, R. Prater

  15. Access to improved H-mode (advanced inductive)

  16. Improved H-mode: current overshoot selected (J. Hobirk, EPS 2011)

  17. Small differences in density and power waveforms can lead to significant improvement on AUG • Pulse very similar • Slightly less gas and lowertarget density for heating • NBI heating increased to 10MW • βN=4.5 and confinement equivalent to H98y2>2 reached • terminated by strong n=1 mode • Extended ELM-free phase before crash • Also radiation increases strongly before crash (Slide from EPS 2011 talk J. Hobirk)

  18. Improved H-mode: recovery of the pre-W scheme Ip ncore nedge Ptot PRF H98 WMHD 0,div 0,main D2 puff Te0, Ti0 • #20993 : year 2006 • ICRH limiters still graphite • #27056 : year 2011 • All tungsten • ?? days after boronization • Major differences • - replace ICRH by ECRH • wave form gas puff • Already quite close but • ramp-up and H-factor • not fully recovered

  19. IOS 4.3 : nu* scaling of advanced inductive Szenario No dedicated discharges in 2011: try to learn from rho* scan Scaling: I2 = c I1, B2 = c B1, T2 = c2 T1, n2 = n1 *2 = c -4 *1 minimum sensible c = 1.2 yields factor 2 in * Problem (in AUG): n/nGW varies as 1/c, how wide can it be varied? Try to connect to rho* experiment (see C. Challis for JE 4.2), including attempts to rise density.

  20. H98 Wmhd Ip Gas ncore nedge H PNBI PECRH Te #27224 #27052 Gas puff scan in rho*-scan shape and q95 rho*-scan lowest density attempt to increase density

  21. Density profile can only be varied by 1.12 both @ 2.6s #27224 #27052 scaled So far, good match of shape

  22. ECRH scheme used : compensated toroidal lauch pECRH jECCD

  23. Torbeam: Poor absorption for n2 = 1.15 n1

  24. Proposed solution: increase q95, Bt by 5% Allows smaller tor. injection angle, simulation with n = 1.2 nrho*

  25. The high Ip, Bt case can be heated on low field side

  26. Reasonable agreement of ECRH power deposition high * case q95 = 4.4 Bt = 2.37 T Ip = 0.93 MA ne0 = 10.3 x 1019 m -3 rho* case, #27224 q95 = 4.2 Bt = 2.26 T Ip = 0.93 MA ne0 = 8.6 x 1019 m -3 low * case q95 = 4.4 Bt = 2.85 T Ip = 1.12 MA ne0 = 10.3 x 1019 m -3

  27. IOS-4.3 : AUG-Proposal for 2012 • - repeat rho* pulse with 5% higher Bt and modified ECRH angles • increase density by 20% • increase Bt and Ip by 20% • adjust gas puff and power to match scaling requirements • 5-10 shots depending on number of iterations • May still be modified after this meeting

  28. IOS-5.2 : ICRH gas puff Increase of AUG ICRF antenna loading by local gas injection Old results: if gas injected locally, antenna loading is significantly higher (doubled in our case) [Ph. Jacquet, V. Bobkov et al., to be submitted to NF] No experiments done in 2011: restrictions in infrastructure of antenna gas injection which was transfered to another antenna 2012: new infrastructure, measure the local effect in large type I-ELMy plasmas, check loading depence on RF power at low power V. Bobkov

  29. AUG : Hardware upgrades and time line 2012 • Number of RMP coils doubled, allows n=4 perturbation • Power supplies to rotate perturbation delayed (no pref. funding) • Design of 8 mid-plane coils ready, but no preferential EU funding • Limiters of ICRH antenae will be partially boron-coated • New antenna design with reduced stray field ready, • Financing unclear, coop with Italy and/or China • 1 additional ECRH unit (1 MW) in spring 2012 • Total power in plasma at 140 GHz close to 5 MW • Restart January 2012 • End of campaign November 2012 • 6 weeks without operation in August / September

  30. AUG : ICRH Upgrades 2012: two antennas with B-coated side limiters to make operation easier After 2012: two new 3-strap antennas for better compatibility with W wall (V. Bobkov et al.)

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