ryan.short@LIGO.ORG - posted 09:02, Thursday 23 April 2026 (89983)
BS OpLev Damping
Since we've found the BS OpLev damping on and causing the suspension to be moving around more than we'd like during prep for the swap to the BBSS, I went through Guardian nodes looking for all the places the OpLev damping is either turned on or off as a learning exercise for myself:
| On/Off | Node | State | Method |
| ON | SUS_BS | ALIGNED | All inputs and outputs on |
| ON | ISC_DRMI | DOWN | Inputs and outputs on, gains to 300,650 (P,Y) |
| OFF | ISC_DRMI | ENGAGE_DRMI_ASC | Gains ramp to zero (only if using MICH ASC) |
| OFF | ALIGN_IFO | MICH_DARK_ALIGN |
Gains ramp to zero |
| ON | ALIGN_IFO | MICH_DARK_OFFLOADED | Gains to 300,650 (P,Y) |
Basically, the BS OpLev damping is ON during alignment and lock acquisition, and is turned OFF once MICH ASC is engaged. To keep the OpLev damping off for the time being, I've set their gains to zero since the suspension node doesn't change those and we won't be going through any states that do for a while.
When the BBSS is installed, we should think about how if at all these interactions need to change (although I'm sure someone already has).