1. Phase II GAS SYSTEM FRC1 Finance Review Committee Meeting CAST experiment K. Zioutas  axion academic training CERN 2/12/2005

2. Phase II GAS SYSTEM Left Image: Reference Point (Crosshairs and Pointer in line with magnet axis) Right Image: Image of the Sun taken in March 2005 Green: Reference Point Red: Solar disk with solar core (10% and 20% of solar diameter) Blue: Field of View (Magnet) Solar Filming in Spring 2005

3. Phase II GAS SYSTEM  Systematic error: Uncertainty of geometers‘ measurement (< 0.006°) Reading accuracy of alignment pictures (< 0.005°) Error in picture analysis, Matlab (< 0.015°) Error of superimposition (< 0.008°) Systematic error small due to: Unmodified focus setting (5-7m) Clear alignment pictures Solar Filming in Fall 2005

4. Phase II GAS SYSTEM Summary Solar Filming 2005 Results March 2005 - Filming Mode Pictures: - Tracking Mode Pictures: Refraction correction smaller than expected Small shift in x-direction Magnet pointing slightly too high and too much to the right (=ahead in tracking) Test of different settings, magnet not in operating condition Results September 2005 - 23.9. & 24.9.05 (Filming Mode): - 28.9.05 (Filming Mode, Added pictures): CAST IS POINTING TO THE SOLAR CORE WITH A PRECISION (0.02°) Tendency (within errors): Magnet slightly too high and a bit to the right [Magnet acceptance about 0.5°, solar core 0.05°-0.11°]

5. Phase II GAS SYSTEM HELIUM GAS SYSTEM  Present 4 He Gas system  Quench Tests  Thermoacoustic  Oscillations  Future 3 He Gas system

6. Phase II GAS SYSTEM FRC6 PRESENT 4 HE GAS SYSTEM Completely Operational Evacuation of all volumes at room temperature Leak testing of all volumes at room temperature Metered transfer of 4He into the magnet bores Includes 12 temperature sensors, and several accurate pressure sensors constantly monitored Includes TAO’s dampers Allows accurate pressure ramping (within CAST spec.) Safe in case of quench FUNCTIONS

7. Phase II GAS SYSTEM FRC7 Quench Tests Identification of the magnet warm up time, and temperature transient during a quench. Estimation of the fluid dynamics, during the removal of the gas. Very important to estimate the necessary robustness of the X-ray cold windows Very important for the design of the final system. OBJECTIVES In total 7 provoked quenches took place. Different gas pressures Different magnet current (up to 13000A) Enabling/Disabling gas removal RESULTS Best knowledge of temperature transient during a quench (best time resolution ever tested in LHC magnet) Identification of thermally driven acoustic oscillations of the gas column.

8. Phase II GAS SYSTEM FRC8 THERMOACOUSTIC OSCILLATIONS Thermoacoustic oscillations were observed with 4He gas filling for p > 2mbar with f=3.7Hz and ~5%amplitude. Phenomenon was studied and solutions designed and produced (damping plugs) Measured amplitude is now of the order of 0.25%. Studies were taken to see the effect of the oscillations. Final system is design to prevent the appearance of such oscillations

9. Phase II GAS SYSTEM FRC9 FUTURE 3 He GAS SYSTEM FUNCTIONS Purge of oil in the hermetic 3 He pumps 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 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.

10. Phase II GAS SYSTEM FRC10 Optical design of LLNL X-ray optic 14 nested shells –125 mm long –Each coated with 300 Å of Ir Distance from front of optic to detector is 1.3 m Outer shell is larger than magnet bore to allow for error in alignment