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Status of the Commissioning of the ILA

Status of the Commissioning of the ILA. Presented by F. Durodi é 4-Jul-2008. Remarks. Contribution of many colleagues in and outside the ILA (core) team Most of the (higher performance) data was obtained on the lower half technical difficulties on the control of C 2

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Status of the Commissioning of the ILA

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  1. Status of theCommissioning of the ILA Presented by F. Durodié 4-Jul-2008

  2. Remarks • Contribution of many colleagues in and outside the ILA (core) team • Most of the (higher performance) data was obtained on the lower half • technical difficulties on the control of C2 • lost control definitively after 23/7 • uncertainties in ZT (upper as well as lower half) appear to affect the upper half more • run away when closing in on match of one of the 2 matching solutions

  3. Highest power coupled in L-mode • 1.85 MW (APTL) - 0.35 MW (losses) = 1.50 MW coupled • L-mode ROG 4 cm

  4. Highest Voltages (L-mode) • ~ 35 kV @ 1.5 MW (APTL) - 0.35 MW (losses) = 1.15 MW coupled • pulses in preparation of L H mode transitions • using ROG sweeps : 4cm  6cm and activiate algorithm only after sweep

  5. Highest Voltages (H-mode) • Lower half : H-mode ROG 4cm • ~ 36 kV (- 38 kV max) @ 1.3 MW (APTL) - 0.35 MW (losses) = 1.05 MW coupled

  6. H-mode ROG scans • Higher sensitivity to tripping at larger ROG • Preliminary : need to asses size of ELMs in various pulses • (possibly slightly ROG dependent ?) ROG ROG

  7. Trips during ELMs (73603) • On the smaller ELM’s the VSWR decreases • cfr offset matched 2nd stage • Trips only at (somewhat) larger ELMs • Time resolution on RF data not sufficient to determine if it is lack of load tolerance or a genuine arc max(VSWR34,VSWR78) Da [V]

  8. Control difficulties of C2 • before 23/7 • substantially rescaled signal • scaling more or less stable over the previous weeks • Noise on remaining sensor did not affect RF signals • Bosh controller appeared to be able to filter the noise and keep C2 in a more or less steady position • from 23/7 • extreme difficulties to find the correct possition for C2 • scaling modified • RF signal fluctuations synchronized with noise on position sensor • Capacitor position is no longer sufficiently steady Match control issue

  9. Probable ZT estimation issues • Despite several attempts to approach the matching solution of the upper half from different starting points this solution appears unstable • The sign of the reactive part to ZT , XT, that must be used to balance the voltages depends on the matching solution : however on the lower half the sign of XT is independent of the chosen matching solution • from there we estimate that there is an offset of about 2 Ohm on XT (XT reads too high) • the current thinking on the origin of this discrepancy is the observed cross-talk on the digital databus signals between APDM and PXI.

  10. Simulation Measurement Solution 1: ZT=6+1j Solution 2: ZT=6-1.7j Solution 1: ZT=6-1j Solution 2: ZT=6-3j RDL balanced Toroidally unbalanced (v3/v7~1.2) Fully balanced • For solution 1, Im(Zt) must be positive • The simulation give a positive imaginary part for solution 1 even if the interstrap coupling increase • Poloidal interstrap increase involes the absolute (Im(Zt)) raising to reach a perfect match Capacitor positions are closed to the measurment ones and global behavior is fine exept for the unbalanced strap voltage Something wrong on the electrical behavior or on the calibration (APTL) APTL phasing and module ? A. Argouarch

  11. APDM cross-talk • One possible suspect : cross-talk between APTL forward and reflected voltages in the APDM’s • has been tested yesterday : (first impression) effect minimal … ~13 deg

  12. ILA Session 02-Jun-2008 / 73007 • Matching • ROG • ILA long pulse (56  61s) • 4cm (ILA profile)

  13. ILA Session 02-Jun-2008 / 73016 • Matching • ROG • ILA long pulse (56  61s) • 4cm (ILA profile)

  14. SMAD / SHAD • SHAD : • So far the SHAD has not yet detected any arc (PJ) (despite there have been arcs) • SMAD : • Principles verified on slow (JPF) data • Appear OK near match • tendency to drift on some pulses (DVE) • SMAD coefficients have been computed • SMAD operates on the raw APDM data : calibration of signals is folded in SMAD coeffs (EL) • No data taken until now with SMAD hardware • issues with APDM – SMAD databus handshake • however expect to be able to take data in the coming days

  15. SMAD principle on JPF data 72871

  16. Conclusions • ILA : Encouraging initial results on H-mode, however • still uncertainties on ZT which could affect the performance • Load tolerance to be optimized • fast DAQ (CODAS) and SMAD will be available in the coming days • Arcs vs. Mismatch •  Sensitivity to ROG • Substantial difficulties : • Control of C2 • installation of ex-vessel monitoring planned • caveat will require a learning curve to operate • Control of match on RDL12 • ? Uncertainties in ZT or somehow linked to control of C2 • Matching the whole ILA • very sensitive to relative phasings of RDLs • Not much progress yet on dynamic simulation • ? Origin of difficulty of matching RDL12 • Substantial worries : • Coupling ! (especially at larger ROGs)

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