User name K. McCormick
Log entry time 16:10:34 on June 3,2002
Entry number 85148
keyword=Cryotarget Auxillary Heaters are BROKEN
In the process of trying to diagnose why the loop 1 auxillary heater wasn't working,
the heater burnt out. There are now no auxillary heaters for the target.
The target now has to be rebooted carefully to make sure the deuterium loop doesn't freeze.
If the target IOC has to be rebooted, try to do the following things:
1. If there's steady beam, keep the beam on during the target reboot. This will
keep the target from cooling down.
2. If the target IOC has to be rebooted and there's no beam, try to close the JTV
about 10-15%. This will make the heat load on the target reasonable so you can
reboot without freezing it. This may or may not be possible, depending upon just
how "crashed" the target IOC is really.
3. If you can't control the JTVs or the beam, then do as quick a reboot as possible.
This means go into the middle room and press the "Reset IOC" button for a few seconds just ONCE and then wait for the reboot to finish. While you are waiting, watch the Loop 1 target temperature. If it goes below 18.7 K, there's a chance the target can freeze. If the target IOC shows no sign of rebooting and you're sitting below 18.7 K for a few minutes, then throw the switch that says "Close JT Valves". This closes ALL THREE VALVES. This is very serious as all of the valves will have to be reopened and the target will have to be recooled, but it's better than freezing the target. ONLY DO THIS IF THE REBOOT FAILS FOR SOME REASON AND YOU'VE BEEN SITTING FOR SEVERAL MINUTES BELOW 18.7 K ON LOOP 1.
The method that I recommend is method 1, rebooting with beam on target. If there's no beam and the reboot doesn't need to be done immediately (i.e. the PID control is still working) then just wait for the beam to come back before rebooting.