Stuck Indium shutter
This is relevant for the indium shutter on Bravo as of Winter 2021/2022. Consult the Stuck group III wiki page for non-indium sticking issues (Stuck Group III Shutter)
SDM Jan 2022
Procedure
General procedure to unstick indium shutter:
Realistically, the growth day is over if not delayed by many hours, so best to idle any other cells you have hot for the growth day
Idle the base at manual zero power. The warmer the base, the more indium flux is emitted from # the indium charge, thus more indium gets on to the shutter
Keep the tip hot around 1000 C in auto mode is fine
Warm the source flange water chiller set point
At UT Austin: This is up in the Mezzanine on the Echo side. Increase the set point of the chiller from 35 C to around where it reaches its max (somewhere around 45 or 50 C). WARNING: the SF chiller cools both Bravo and Echo, so doing this during a growth day for someone on Echo is dicey and it could lead to cell instabilities or trip interlocks and idle the MBEs unintentionally. The SF water set point for BOTH the Bravo and Echo interlocks down at the MBE control panels should be set very high on Bravo (like 55 C, well above the 45 or 50 C max in the Mezzanine). It is best to have a knowledgeable older Echo grower present monitoring Echo for issues or tripped interlocks, and to have a plan in case an interlock is tripped, e.g. open the group-V valves by hand, close/unplug relevant pneumatic valves, manual and zero sources to prevent current flashing the filaments, etc.
Warming the SF chiller takes 2 to 4 hours...
With the tip at 1000 C and the chiller still warming up, try wiggling the shutter free, you might get lucky. Be gentle
You can also remove the substrate/CAR heater block and point the bare substrate heater toward the indium cell pocket to provide additional radiative heating. Keep it in manual power mode around 200 to 300 C with the BF gauge off. NOTE: Whenever the shutter is eventually unstuck, you should rotate the CAR so that the exposed heater is not getting coated with indium!
Once the SF chiller is around 45 or 50 C, continue gently wiggling the shutter and bellows.
If possible, adjust the externally adjustable components of the shutter, much like shutter alignment at the beginning of a campaign post-maintenance. NOTE: In the process of adjusting the shutter's externally adjustable components, you are effectively misaligning the shutter, which is something you will have to rectify after successfully unsticking the shutter. Also NOTE: the heated viewport is hot and might be close to where you will be adjusting the shutter, so consider turning it down to not burn your hands
With the SF chiller hot, the substrate heater pointing at the indium pocket, and the tip/base at 1000/idle there's not much more heat you can provide. It might require a fair bit of patience and persistence to unstick the shutter over the course of a few hours by adjusting/wiggling the shutter and bellows. NOTE: It helps to have additional eyes on the cell through the viewports to help tell you if any of your adjustments are working (e.g. someone telling you to go “higher” or “lower” in the pocket) or if you're caught on indium blobs
Once you successfully unstick the shutter or you give up for the day, return the system back to its nominal state
At UT Austin: Turn the SF chiller back to 35 C in the Mezzanine, return the substrate heater/CAR to a covered state with a block and put the CAR in the transfer position with the BF gauge on, idle the indium tip and base and return to auto mode). Turn up the heated viewport. If you unstick the shutter, readjust the shutter to a safe position to mitigate it getting stuck again!