awade and I managed to lock both cavities today after diagnosing the acromag communications issues. Some stats:
South Slow Voltage: -6.12 V
North Slow Voltage: 3.46 V
Vaccan Temp: 30 Celcius
Marconi FM Devn: 25 kHz
Marconi RF Lvl: +12.6 dBm
Trans Beatnote Frequency: 82.4 MHz (and drifting up at ~5 kHz/s)
Channels dumped into acromag1 at /home/controls/CTNWS/data/20171030_161251_ChannelDump.txt
awade is currently playing with the Marconi to try and get the FM Devn down to around 1 kHz so we can get a spectrum that is not limited by actuation noise. Beatnote frequency drift is settling down significantly as I type this, so it could be possible soon.
∆f/f = ∆L/L for the Fabry Perot cavity. f = 282 THz, L = 3.68 cm, and ∆f = ~ 5 kHz/s implies that ∆L ~ 6.5e-13 m/s for our relative cavity length changes.
From elog 1874, we have ∆T ~ ∆L / (alpha * mirror thickness), where alpha = 5.5e-7 [1/Kelvin] and mirror thickness = 6.35 mm. We get a relative temperature drift of ∆T ~ 0.2 mK / s
We seem to have underestimated how stable our cavities must be to temperature drift. In any case our beatnote is still drifting rapidly despite the vaccan stabilization.