Jennie W, Sheila D, TJ S,

Summary: JAC HEATER guardian can cool/heat the JAC body but is not optimised yet.

Today TJ and I tested the guardian I wrote yesterday. We still haven't optimised the gain and setpoint to choose. Included is trends from today showing that we could cool down the JAC but we eventually run out of range on the heater (and on the PZT fast feedback) so I think we want to choose a set point where the heat load is around a couple of W constantly.

In addition, because we were increasing the temperature of the remaining water moelcules in HAM1 (which is still pumping water out of the vacuum volume) we cause the pressure to slowly rise in the chamber if we have too much heat on the JAC. This should not be a problem once we reach hard vacuum.

TJ and I are going to rewrite the cdsutils.servo function so we have more tuning over the feedback settings. The current function will send the guardian node into error when the heater power reaches 0 as it keeps trying to step the channel to negtaive values. We also have to turn the servo off and on again in order to change the gain and set point.