Hi SR3 team,
May I ask you one question?: on the other day I failed to excite the lowest whole chain resonance mode with IP actuators. Also yesterday, I failed to observe the optic yaw peaks below 100mHz when I measuerd its spectrum without any controls. According to the simulation, we should have the whole chain mode at about 50 mHz and payload yaw motion at 150 mHz and 170mHz (#1, #5 and #6 on wiki), however, the whole chain mode is not visible, though the payload yaw peaks at about 150 mHz are (slightly though). Is this because that the MD is already much close to the Cu ring on SF? or somewhere of the payload is touching to somewhere? If this is due to the MD, you will see the lowest peak when the MD is much far from the Cu ring. Could someone check this? Also, can you check the condition of the air shield of the OpLev maybe?
The atached files are the spectra of suspension yaw motion of BS and SR3 without any controls.
Thanks
On behalf of SR3-MD team: Enzo, Rikako,
[Note: This is a project to optimize the gap between the magnetic damper and Cu ring of SR3 suspention]
For a test of the issue (klog5838), they changed the height of the magnetic damper (MD) mechanically by 1 mm (klog5850) from the postion used in klog5838. The attched figures are the spectra in Yaw DoF of IP/IM/TM_OpLev. Figure1 and figure 2 show the spectra before/after adjustment respectively. Then the peak(s) at around 150 mHz became steaper in all those DoFs, also the lowest mode seemed to show up. The candidate resonance modes which correspond to those are mode#1/#4(/#5/#6) and this looked consistent with the height adjustment; the peaks which became steaper are the ones to be damped by MD. (The peak at 0.4 Hz in IP(Y) looked a resonance of IP in L/T and thus we have to diagonalize the sensormatrix for IP-LVDTs later. This mode is also the one which is tp be damped by MD in some extence.)
They will try to make larger gap and check if they can find/excite the lowest yaw peak. we will see tomorrow.
The measurement files are stored in:
/kagra/Dropbox/Subsystems/VIS/TypeB/Hatoya/spectra_monitor/
Thanks for your help/check btw!:)