Jennie W

I still have some work to do on the JAC heater but it has stayed locked for 3 days, since Friday when we took the JAC down for an unrelated reason.

There is still some oscillation around the set point but the PZT length fb is staying within  a 77V range.

We might need to check this again once we are at 62W for long periods as this will increase the heat load.

We have gone to 10W for periods less than an hour and can see no difference in the PZT length fb over this time.

This is too short a test to say how the cavity will respond to an increased heat load.

The last time I switched the heater off (first cursor) after I reverted some guardian changes on Wednesday that rang up the temperature servo, the system took  2.5 hours to cool down by 0.1 degree C (second cursor), this was the minimum temperature it reached before I switched the heater back on 6 hours later.

Aftyer switching the heater back on with the controller running the temperature took 19 hours roughly to reach equilibrium.

I'm still trying to calculate what frequency to put my lead compensation filter at to speed this up.

Summary: JAC heater working well and staying locked for multiple days at 2W and 10W input power but more tests needed at higher power. The step reponse time is still on the order of 1 day for the system while under control so some more filter changes are neccessary.