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HELIUM4 GAS SYSTEM STATUS

HELIUM4 GAS SYSTEM STATUS. >Status update >Result of TAO Tests >Thermodynamic behavior of the gas >Computational fluid dynamics simulations. Nuno Alexandre ELIAS (PH-DI). 29 th CAST Collaboration Meeting – Patras (22-23 May 2006). 4He Gas system status update.

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HELIUM4 GAS SYSTEM STATUS

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  1. HELIUM4 GAS SYSTEM STATUS >Status update >Result of TAO Tests >Thermodynamic behavior of the gas >Computational fluid dynamics simulations Nuno Alexandre ELIAS (PH-DI) 29th CAST Collaboration Meeting – Patras (22-23 May 2006)

  2. 4He Gas system status update • Intervention in Mars (Opened MFB below to Cryostat) - Installation of new pressure probe on the cold bore PTAO - Installation of new Temperature sensors inside the cryostat - Closure of Cryostat • Search for TAO’s with new pressure sensor • Vacuum measurements (optimize parameters and get noise level) • Pressure fillings (ø, 2, 4, 6,8,10 mbar fillings) • Data taking preparations • Gas filling of the cold bore to last pressure setting before intervention • Quench at 12900A, Transient on PTAO • Data taking Runs • 15 new gas settings [total 43 → P= 3.58mbar (@1.8K)] • Fluid mechanics inside the cold bore • Computational Simulations of Gas behavior • PATRAS (experiment coasts) Nuno Alexandre ELIAS [PH - DI]

  3. 4He GAS SYSTEM Nuno Alexandre ELIAS [PH - DI]

  4. THERMOACOUSTIC OSCILLATIONS (past) • Thermoacoustic oscillations were observed with 4He gas filling for p > 2mbar with f=3.7Hz and ~6% amplitude (dp/p); Isentropic model gives 3.5% density fluctuation (dr/r). • Phenomenon was studied and solutions designed; Damping plugs installed on the linking pipes Nuno Alexandre ELIAS [PH - DI]

  5. Search for TAO’s with new pressure sensor • New pressure sensor was installed inside the cryostat reading directly the pressure of the cold bore - Frequency spectrum of the pressure over all the measure pressure range shows NO modal oscillation with dominant frequency ~3.7 Hz above the noise level ~0.1% of the pressure setting and no relevant signal, compared with the vacuum case, was registered, other spikes attributed to electronic noise. Nuno Alexandre ELIAS [PH - DI]

  6. QUENCH Update to the quench transient curve • New pressure sensor allowed to give better resolution of the curve for t<t0+100 milliseconds • Its possible to compare the pressure increase downstream and upstream of the TAO damper • New pressure sensor reacts faster than 100ms Nuno Alexandre ELIAS [PH - DI]

  7. Model j –gas panel volumes Calculation is done taking stable conditions of the gas pressure in the metering volume • Gas sent to the cold bore • Gas in cold bore Sum of all fillings Looking at the gas inside • Can we assume the gas is at the same temperature as the cold bore? • Is Tcryo a good indication of the temperature of the gas through all the cold bore? • How does convection from hot regions affects the homogeneity of the gas inside the cold bore?? • How does the gas pressure affects these convectional effects?? • And the inclination of the magnet?? • Can this affect the coherence?? • Measurement techniques for gas density?? (laser interferometer?) Nuno Alexandre ELIAS [PH - DI]

  8. CFD simulations • Solid model of SS tube, outside magnet • Temperature distribution along the pipe ( region with high temperature gradients) • Does not take in consideration convective heat transfer due to gas • Over 66,000 elements • But this does not answer the question of what happens to the gas density Nuno Alexandre ELIAS [PH - DI]

  9. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • Covering all the magnet length (712,000 elements), long processing time • Temperature on surface is an imposed boundary, coming from the solid model (future will include both fluid and solid model), windows are adiabatic. Nuno Alexandre ELIAS [PH - DI]

  10. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore MAGNET HORIZONTAL, 3mbar Nuno Alexandre ELIAS [PH - DI]

  11. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • Only magnetic length (9.26m) • From window to window MAGNET HORIZONTAL, 3mbar Nuno Alexandre ELIAS [PH - DI]

  12. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • Only magnetic length (9.26m) • From window to window MAGNET HORIZONTAL, 3mbar Nuno Alexandre ELIAS [PH - DI]

  13. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore MAGNET TILTED (+8º,mfb_up), 3mbar Nuno Alexandre ELIAS [PH - DI]

  14. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • Only magnetic length (9.26m) • From window to window MAGNET TILTED (+8º,mfb_up), 3mbar Nuno Alexandre ELIAS [PH - DI]

  15. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • Only magnetic length (9.26m) • From window to window MAGNET TILTED (+8º,mfb_up), 3mbar Nuno Alexandre ELIAS [PH - DI]

  16. CFD simulations (preliminary) • 3D Computational fluid dynamics (CFD) model of gas inside the cold bore • From window to window • Only magnetic length (9.26m) MAGNET TILTED (+8º,mfb_up), 3mbar Nuno Alexandre ELIAS [PH - DI]

  17. CFD simulations (preliminary) • CONCLUSIONS: - Simulations to continue with more accurate model, finer mesh, both solid and fluid. • Simulations to be extended to other pressures, angles, and different X-ray window temperatures (heating); decision to be taken on running conditions; • Search for density measurement techniques (to scan the cold bore length) • Results to be studied, to see possible effects on small reduction of coherent length and its implications. • Heating effects of the gas on the magnet extremities, might result on a broadening of the density steps when compared with the specified, study! - TAO’s should be avoided in future system because this would increase the heat transport to the cold bore. Nuno Alexandre ELIAS [PH - DI]

  18. 3He GAS SYSTEM >Functions >Requirements >Schematic >Open questions >Ongoing work >Updated Cost Estimate Nuno Alexandre ELIAS (PH-DI)/ Tapio Niinikoski (AT-ECR) 29th CAST Collaboration Meeting - PATRAS

  19. 3He GAS SYSTEM • FUNCTIONS Purge of oil in the hermetic 3He pump Evacuation of all volumes at room temperature Leak testing of all volumes at room temperature Transfer of 3He from pressurized transport cylinder into the storage vessel of the gas system Metered transfer of 3He into the magnet bores (by pressure stepping and continuous ramping) Recovery of 3He in the event of a magnet quench Normal recovery of 3He Regeneration of charcoal traps Transfer of 3He back into the pressurized transport cylinder. Nuno Alexandre ELIAS [PH - DI]

  20. 3He GAS SYSTEM • REQUIREMENTS Safety against loss of 3He Precise metering of the amount of 3He in the magnet bores (Double filling per run and possibility to make pressure ramping) Absence of thermoacoustic oscillations Protection of the thin X-ray windows in the event of a quench. Remote data logging of the state of the gas system, without feedback No safety release of 3He elsewhere except to the safe storage vessel. Nuno Alexandre ELIAS [PH - DI]

  21. 3He GAS SYSTEM • Storage • Purging • Metering and Dosing/Ramping • Axion conversion region (cold bore) • Expansion volume • Recovery and circulation Nuno Alexandre ELIAS [PH - DI]

  22. 3He GAS SYSTEM • OPEN QUESTIONS: • METERING AND DOSING: • Option A > 2 metering volumes, filling is done before and in the middle of the run. Precise, not cheap, low flexibility. All detectors ‘see’ the same setting. • Option B > 1metering volume for 2# settings ramping during tracking, Requires mass flow meter + controller for constant ramp rate, more flexible, Absolute precision lower than A, possible TAO’s • Option C > Continuous ramping covering more than 2# settings, Requires mass flow meter + controller for constant ramp rate, more flexible, Absolute precision lower than B, possible TAO’s • Option D > Continuous ramp down during tracking. Less disruption of the magnet than A, B and C, low precision, Requires mass flow meter + controller for constant ramp rate, more flexible (ramp rate can be changed), possible TAO’s • RUN CONDITIONS • Warm windows > Low cryopumping of desorbed gases into the window foil, good for window transparency. (effect on X-rays ??) • Cold windows > Low heat transfer into the cold bore, good for gas stable density and magnet. • X-ray Windows > PMAX. - Sudden Increase of pressure at cold, more testing Nuno Alexandre ELIAS [PH - DI]

  23. 3He GAS SYSTEM • Technical Design Report is ongoing should be finalized soon. (some decisions to be done) • Description of Functions, operations and safety matters • Main equipment specifications and dimensions • Main work packages identified: • WP1-Platform for 3He pump + accessories, • WP2-Design of the integration of new cryogenic and check valves inside the cryostat. • WP3-Modifications of gas lines inside the cryostat • WP4-Modification of cryostat to pass cryogenic valve head • WP5-Installation of new cryogenic and check valves • WP6-Construction of Storage volume • WP7-Construction of Expansion volume • WP8-Construction of metering volumes • WP9-Construction of command panel to operate 3He pump and electro-pneumatic valves. • WP10-Construction of gas panel • WP11-Installation of new cryogenic pressure transducer • near FUTURE: Start drawings of integration, and invitations to bid of main equipment, discussions with suppliers. Nuno Alexandre ELIAS [PH - DI]

  24. Updated Cost Estimation Nuno Alexandre ELIAS [PH - DI]

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