1. Spectrometer Solenoids MICO 214 Steve Virostek LBNL February 6, 2013

2. Current Status The magnet was cooled down using LN Wednesday-Friday last week with 24 hr monitoring. Some liquid nitrogen had collected in the cold mass and was removed with a warm He purge followed by 5 cycles of pump/purge. LHe cooldown and filling completed last Friday evening; system was initially losing helium due to high shield temperatures (~200K). As of last Saturday, the magnet temperatures had reached their normal operating condition. The new cold mass heater control loop is operating as designed; with excess cooling power, the heater is maintaining a set positive pressure The magnet training will likely start today, after a few additional power supply tests (see next page). We currently have 3000 liters of LHe on hand; an additional 2000 liters is scheduled to arrive on Monday.

3. Power Supplies A new TDK-Lambda power supply for the E1/Center/E2 coils has been installed; all PS rack components now running on 220V. Off line power supply tests carried out last week (including trims). All five power supplies have been fully integrated with the control system. Tests with current in the magnet were carried out in the last two days. Issues with one of the AMI 420 controllers resulted in the need for two of the controllers to be shipped from the UK (arrived yesterday). System appears to be fully functional now – tested in an integrated manner to 50 A in the coils (45 A in the end coils). Minor issue with one of the PS/controller sets to be further investigated later today. No voltage issues with any of the HTS leads at 50 A.

4. Other Progress Numerous other enhancements to the control system have been incorporated and have been tested (rack UPS, alarm handler, autoSMS, 2 nd pressure gauge, PS current shunts, cold mass gas bottle backup,…). Independent cold mass heater control circuit implemented for greater reliability. Cryocooler tests currently under way – 4 coolers purchased by U. Miss. being tested by Wang NMR for condensing power. One additional cooler test will determine the performance loss due to double length helium lines.

5. 2 nd Magnet The second magnet construction is continuing at Wang NMR. The cold mass has been installed in the vacuum vessel and aligned. Radiation shield has been suspended in the vessel, and the shield bore and end plates have been welded in place Radiation shield temperature sensors have been routed towards the vessel tower MLI on the outer radiation shield is complete Tower assembly consisting of outer stainless steel box, 1 st stage copper plates, cryocooler sleeves and warm leads nearing completion Completion expected in approximately two months