Today I restarted the PSL after it was purposefully shutdown for the duration of the holiday break. The HPO and 35W FE restarted with no issues, but I did run into an issue while injection locking the two lasers; the injection locking was very unstable. To ensure the system was at thermal equilibrium I let it warm up for the morning and roughly half of the afternoon before investigating the instability. By 20:00 UTC (12:00 PST) the injection locking had become more stable, but was still having occasional relocks. I lowered the ILS gain voltage from 1.0 V to 0.5 V (this is actually a gain increase) and things became more stable. I also noticed that the SR560 used to boost the low frequency gain of the ILS servo was saturated; I could not get it to clear at the time. Checking on things again at 22:00 UTC (14:00 PST), the injection locking had stabilized further. As a double check I looked at the PDH error signal for the injection locking and saw no issues there; this required me to unlock the ILS to see the error signal. Upon relocking the ILS things looked much more stable, and at about this time I also noticed that the SR560 was no longer saturating. I turned on the TFIN for the ILS (the signal path we use to boost the ILS low frequency gain) and the signals looked much better. I left it in that state to continue to warm up for the rest of the afternoon. As of 23:54 UTC (15:54 PST), the system looked stable and operating normally. At this point in time I re-enabled the power watchdogs.
I re-enalbed the PMC, FSS, and ISS at ~23:00 UTC (~15:00 PST). All 3 came back without issue. I will continue to monitor the system, but as of right now everything appears to be running normally.
I also took this opportunity to do the weekly PSL FAMIS tasks during the morning.
HPO Pump Diode Current Adjustment (FAMIS 8455)
With the ISS still OFF, I adjusted the pump diode operating currents and temperatures this morning as part of the PSL restart. The changes are summarized in the below tables and a screenshot of the PSL Beckhoff main screen is attached for future reference.
| Operating Current (A) | ||
| Old | New | |
| DB1 | 53.7 | 53.9 |
| DB2 | 55.4 | 55.6 |
| DB3 | 55.4 | 55.6 |
| DB4 | 55.4 | 55.6 |
| Operating Temperatures (°C) | ||||||||
| DB1 | DB2 | DB3 | DB4 | |||||
| Old | New | Old | New | Old | New | Old | New | |
| D1 | 26.5 | 26.0 | 19.5 | 20.0 | 20.5 | 21.0 | 22.0 | 21.5 |
| D2 | 26.5 | 26.0 | 19.0 | 19.5 | 24.5 | 25.0 | 19.5 | 19.0 |
| D3 | 26.5 | 26.0 | 20.0 | 20.5 | 24.5 | 25.0 | 21.0 | 20.5 |
| D4 | 26.5 | 26.0 | 18.0 | 18.5 | 21.5 | 22.0 | 19.5 | 19.0 |
| D5 | 26.5 | 26.0 | 18.0 | 18.5 | 25.5 | 26.0 | 21.5 | 21.0 |
| D6 | 26.5 | 26.0 | 18.5 | 19.0 | 20.0 | 20.5 | 21.5 | 21.0 |
| D7 | 26.5 | 26.0 | 19.0 | 19.5 | 21.0 | 21.5 | 21.5 | 21.0 |
At the time of adjustment the HPO was outputting ~154.5 W; this was at roughly 18:30 UTC (10:30 PST). This completes FAMIS 8455.
PSL Power Watchdog Reset (FAMIS 4586)
I turned on both PSL power watchdogs at 23:54 UTC (15:54 PST). This completes FAMIS 4586.
