At present, the temperatures of IY/EY IMs are ~ 45 K because of continuous FP cavity resonance. However, we have no way to reduce the temperature of EY IM because only one cryocooler for the payload is operated, and the other is regarded as having some trouble with cooling performance.
On the other hand, I reduced the voltage to the IM heater for IY from 12V to 11V to reduce the temperature.
To reduce the temp of IY, and EX, I set the heater voltages for each as follows,
[EY IM Temperature increasing]
The temperature of EY IM is increasing to 50K because one of the cryocoolers (REF4) for the payload is not operating.
Before deciding to start this stopped cryocooler (REF4) again, I checked what happened in the photosensors outputs in {V, P, R, L, Y} when two cryocoolers (REF2/4) were operated, according to the trouble in IX. Actually, the operation of two cryocoolers for the payload around -84 days became the trigger for {V, P, R, L, Y} to change. On the other hand, the stop of REF4 cryocooler affected only {V, P, R}.
[ARM side cryocooler performance degradation again]
The temperature of the 1st head of the cryocooler for the arm side duct shield (50K_REFARM_HEAD) is now increasing again. It is dangerous situation again.
Finally, the temperature of the first head of the cryocooler for the arm-side duct shield was over 88K, which was fluctuating around 70K about 1 week ago. The temperature of DUCt _SHIELD_ARM4 is also over 150 K. The vacuum level at EYGV started gradually increasing. Actually, H2O is now gradually increasing.
Anyway, we will start two TMPs this morning. I am now wondering whether to heat up the payload for protection for frosting or not (It will take 4 days to reach ~ 160K).
