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

2. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]2 4He Gas system status update Intervention in Mars (Opened MFB below to Cryostat) - Installation of new pressure probe on the cold bore P TAO - 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 P TAO 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)

3. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]3 4 He GAS SYSTEM

4. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]4 THERMOACOUSTIC OSCILLATIONS (past) Thermoacoustic oscillations were observed with 4 He gas filling for p > 2mbar with f=3.7Hz and ~6% amplitude (  p/p); Isentropic model gives 3.5% density fluctuation (  ). Phenomenon was studied and solutions designed; Damping plugs installed on the linking pipes

5. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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.

6. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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<t 0 +100 milliseconds Its possible to compare the pressure increase downstream and upstream of the TAO damper New pressure sensor reacts faster than 100ms

7. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]7 Model Gas sent to the cold bore j –gas panel volumes Gas in cold bore Calculation is done taking stable conditions of the gas pressure in the metering volume 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?)

8. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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

9. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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.

10. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]10 CFD simulations (preliminary) 3D Computational fluid dynamics (CFD) model of gas inside the cold bore MAGNET HORIZONTAL, 3mbar

11. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]11 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 HORIZONTAL, 3mbar

12. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]12 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 HORIZONTAL, 3mbar

13. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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

14. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]14 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

15. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]15 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

16. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]16 CFD simulations (preliminary) 3D Computational fluid dynamics (CFD) model of gas inside the cold bore Only magnetic length (9.26m) MAGNET TILTED (+8º,mfb_up), 3mbar From window to window

17. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS 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.

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

19. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]19  Purge of oil in the hermetic 3 He pump  Evacuation of all volumes at room temperature  Leak testing of all volumes at room temperature  Transfer of 3 He from pressurized transport cylinder into the storage vessel of the gas system  Metered transfer of 3 He into the magnet bores (by pressure stepping and continuous ramping)  Recovery of 3 He in the event of a magnet quench  Normal recovery of 3 He  Regeneration of charcoal traps  Transfer of 3 He back into the pressurized transport cylinder. 3 He GAS SYSTEM FUNCTIONS

20. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]20  Safety against loss of 3 He  Precise metering of the amount of 3 He 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 3 He elsewhere except to the safe storage vessel. 3 He GAS SYSTEM REQUIREMENTS

21. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]21 3 He GAS SYSTEM Storage Purging Metering and Dosing/Ramping Axion conversion region (cold bore) Expansion volume Recovery and circulation

22. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]22 3 He 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 > P MAX. - Sudden Increase of pressure at cold, more testing

23. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]23 3 He 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 3 He 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.

24. GAS SYSTEM STATUS Phase II 29 th CAST COLLABORATION MEETING -PATRAS Nuno Alexandre ELIAS [PH - DI]24 Updated Cost Estimation