Ability Engineering completed the first "trial-fitup" of the floating coil cyrostat. This revealed complexities with alignmentand procedure that must be corrected. Darren Garnier made several
site visits during the past month, and MIT and Columbia have revisedthe assembly procedure in order to maintain alignment and uniformspacing between the cyrostat tori.
The anti-rotation components have been received after silver plating, adjusted at MIT, and sent to Ability Engineering.
The test cryostat, built to test the LHe bayonets, was assembled.The first tests were successfully completed. With liquid nitrogentransfer and with liquid nitrogen followed by liquid helium transfer, the tests confirmed the o-ring thermal and vacuum design. A more complete test, (with the bayonet at vacuum) will be conducted after repairing a He leak in the test cryostat.
All 12 clamps are tighten around the coil. This process was controlled by calibrated strain gauges installed at each clamp leg. Each clamp was loaded to about 8300 kg. Then the coil was moved to an other building and tested at high voltage to check the ground insulation and by induction method to check turn-to-turn shorts. Both tests were successful. The coil is shown below:
The inner nitrogen can has been fully completed and leak tested. It was then polished at the places near welds and handling points. The copper segments for the upper and lower shield covers have been cut to size. The structural liquid nitrogen ring has been welded to four supports and has been drilled to accommodate nitrogen supplies. The four cryostat supports have been fully assembled, including the welded flat springs and bonded by epoxy to G10 tubes. Four outer cryostat legs for transportation have been machined.
The helium can is being assembled. The upper coil support ring of the helium vessel is now fully machined, including supports for the coil. A lot of other small items (small flanges, fittings, and others) have been machined. The G10 support tubes for the helium vessel have been bonded to their stainless steel fittings.
Alex Zhukovsky visited Sintez during the last week of June. He inspected the completed subassemblies and parts of the cryostat and found them of a good quality. He confirmed that excellent progress has been made in the manufacturing of the coil and cryostat.
The technique has been finalized that will be used to restore conduction cooling to the sections near the outer diameter of the L-coil pancakes that had debonded due to excessive thermal stresses during the thermal cycling that occurred during a liquid nitrogentest. This modification calls for the installation of approximately20 flexible thermal straps to the outer surfaces of each pancake (the surfaces away from the center support plate). The thermal strap design has now been completed. Delivery of the fabricated straps is scheduled for this week.
Additional manufacturing drawings for the L-coil cryostat have been received and are under review. These drawings include modifications to the coil's radial restraint system within the cryostat, and to the cryo links from the cold head to the coil and from the cold head to the current lead thermal anchors.
The lifting fixture of the launcher-catcher is nearing completion. The walkway, providing safe access to the top of the machine, has been ordered.