David Wang started a helium leak check on TM3 at the CS this morning.

David will create an e-log once his check is complete, but here are the preliminary results:

- target oven +/- OK

- mounting support plate OK

- ionizer tube heater +/- OK

- extraction electrode OK

A large leak was found in the heat shield circuit:

- The module pumped down with the leak rate stabilizing at 4.8xE-9 atm.cc/sec
- 60 psi helium was applied to the heat shield fitting on the right side of the Y-shaped connector (see attached sketch, each side of the "Y" is separated by a face to face metal contact only, i.e. no o-ring seal separates supply and return water)
- The maximum leak response was detected in 10 seconds, with base pressure rising from 2.0E-2 torr to 2.8xE-2 torr
- The helium was vented from the line by using an allen wrench to open the valve on the water quick-connect (see attached photo)
- The module continued pumping down, and after some time, the allen wrench was used again to open the valve, but air rushed inside, indicating vacuum was being drawn inside the water line through the leaking interface
- As the module continued to pump, this vacuum vent air rush inside the water line could not be reproduced by opening the valve again with the allen key

The module is currently pumping down at the Conditioning Station. We will leak check the remaining lines tomorrow with whatever base leak-rate we have achieved, and then move TM3 to the Hot Cell for further diagnosis.