Yamamoto kun reported via slack,
- @uchiyama@Nobuhiro KIMURA
Now KGRVAC:CCG_Y30_01:VAL:PRESS reaches 1.2e-5Pa which is the current threshold of the interlock according to klog#32347. But GV at EYA is still open.
Fig.3 shows the X-30 pressure. I and Uchiyama-kun also confirmed that the GV_eya was open. Anyway Uchiyama-kun closed EYA GV by using Switchbot manually, although Uchiyama-kun wondered whether it should be closed or not because this enhancement should be the increase of nitrogen that is harmless for a mirror.
I checked the vacuum level and cryocooler status for EY as Fig.1 and Fig.2. Actually, the vacuum level at EYA CC-10(EYC side) was enhanced, but it started decreasing as in Fig.2. The temperatures also started decreasing as in Fig.1.
I would like to propose,
- set trigger for GV closing: ~ 6*10^-5 Pa (near 10^-4 pa),
- set the slack alert for enhancement of the vacuum level: 10^-5 Pa,
because,
- The serious leak will result in immediate vacuum level enhancement over 10^-4 Pa according to our past experiences. In such a case, the alert time and the closing time are almost the same.
- Slight leaks or Nitrogen releases from cryostats are not so serious for a short time (~ several hours), so we can have time to understand the situation and judge what we should do.
