No obvious reason but after an FSD trip and the usual HPH low power alarm, the heater recovered to an anomalously low level, more like 50-60 W for a few minute period. Decided to ask MCC to reduce the beam current to 130 uA and see how it would settle down.
See attached plot. Look at the middle of the time chart for the HPH power and you will see the changing condition.
Previously we had 146 uA and about 140 W; then it came back to 146 uA and about 60 W. After waiting a while at 130 uA now we have 250 W. So we can try higher beam current again. I don't want to play with refrigerants as Greg will be here at 4 pm anyway.
Figure 1
