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CSC gas studies

CSC gas studies. Valery Andreev (UCLA) Roberto Guida (CERN) April 28, 2008. CSC gas system: faced problems. To be fixed. Mixer Calibration - fixed Purifier : Fast saturation Changing working mixture Pump

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CSC gas studies

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  1. CSC gas studies Valery Andreev (UCLA) Roberto Guida (CERN) April 28, 2008

  2. CSC gas system: faced problems To be fixed • Mixer • Calibration - fixed • Purifier: • Fast saturation • Changing working mixture • Pump • Membranes - replaced by better version • Distribution racks • Flowcells performance - tolerable for the moment • Broken bubblers - protection covers installed • Backup system • Can change mixture ratios - use Ar(40%)-CO2(60%) instead of CO2(100%): done • Huge air intake Ruptured membrane To be understood / fixed V. Andreev, R. Guida

  3. CSC gas operations: Purifier • Saturates in 1-2 days • Could be due to high level of air intake discovered recently • Multiple HV trips after switching ON the purifier • Absorbs/eats CO2 component of the mixture • Safe operation mode to adopt V. Andreev, R. Guida

  4. CSC gas operations Issue: Air intake level • System has been running in closed loop for YE+ since November 2007 • Analysis rack (Water/Oxigen and InfraRed) at SGX5 is running since March 2008 • Oxygen : 4000 ppm (to compare with old (wrong) measurement of 180 ppm) • Water: 330 ppm ( old device measurement -> 50 ppm) • Chromatograph measures ~20000 ppm (2%) Nitrogen • in rough agreement with Oxygen measurement by analysis rack sensor • Big air intake, source is not identified yet • Stop of HV on March 26 • Running in open loop mode since March 27, till things understood / fixed • Costly operation V. Andreev, R. Guida

  5. CSC Status: All positive end under gas Fill mode Purifier under test Gas analysis: Before Purifier O2 ~ 600-700 ppmVol N2 ~ 0,284 %Vol (~2840 ppmVol) H2O ~ 200 ppm

  6. First test for CSC purifier (it was already used) Regenerated with Ar H2 3%, flow 300 l/h V. Andreev, R. Guida

  7. Second test for CSC purifier (it was already used) Regenerated with Ar H2 3%, flow 300 l/h V. Andreev, R. Guida

  8. Measurements at the pre-distribution Return from chambers V. Andreev, R. Guida

  9. ME+1 (unit67) • Return from individual channel • red  ME+1/2 • back  ME+1/3 • Hypothesis for the different concentration: • Different flow • Different leak rate • N2 concentration in the supply line: • 0,03-0,04 % V. Andreev, R. Guida

  10. Bypass test Bypass on disk ME+1/3 27-30 ME+1/3 27 Last week

  11. Nitrogen value vs chamber overpessure Air intake Independent of overpressure ! - to check at 3 mbar yet V. Andreev, R. Guida

  12. Leak test for channel 15 (ME+1/2) 16 (ME+1/3)

  13. Leak rate very similar: <= 1 ml/min (0,06 l/h) Do not explain the different in N2

  14. Increasing the flow, decrease the N2 level  Something it is really different in the chamber V. Andreev, R. Guida

  15. Results from ISR V. Andreev, R. Guida

  16. Results from ISR Gas channel V. Andreev, R. Guida

  17. Results from ISR V. Andreev, R. Guida

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