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| (Gautam put some numbers here for the terms please) | Current best guesses (as of 30 Apr 2019): * T_PMC = 85% * T_IMC * T_FI = 50% * alpha_MM = 98 % * G_PR = 40 (once we put new folding mirrors in) * T_BS = 50% * G_arm = 285 (20 ppm round trip loss) Giving P_arm = Plaser *2400. So if Plaser = 10W, Parm = 24kW. If we improve T_IMC * T_FI to 90%, then the overall gain becomes x4000, so 10 W from the laser becomes 40 kW in the arms. |
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| * Suppress angular modes by XX * Suppress laser noise at the 11 & 55 MHz readout frequencies by XX * Maintain a T_PMC > 0.9X |
* Suppress angular modes by XX (note that the IMC also filters the beam jitter) * Suppress laser noise at the 11 & 55 MHz readout frequencies by XX (this is primarily a PMC function as the IMC transmits the sidebands) * Maintain a T_PMC > 0.9X (if the existing [[ https://labcit.ligo.caltech.edu/~ajw/PSLPMC.png | spec]] is accurate, the best possible T is ~88%) |
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| * what's the MM frac between PMC and IMC? | * what's the MM frac between PMC and IMC? Judging by the [[ https://nodus.ligo.caltech.edu:8081/40m/12898 | IMC visibility]], this is ~98%. |
Power calculation
P_arm = Plaser * T_PMC * T_IMC * T_FI * alpha_MM * G_PR * T_BS * G_arm
Current best guesses (as of 30 Apr 2019):
- T_PMC = 85%
- T_IMC * T_FI = 50%
- alpha_MM = 98 %
- G_PR = 40 (once we put new folding mirrors in)
- T_BS = 50%
- G_arm = 285 (20 ppm round trip loss)
Giving P_arm = Plaser *2400. So if Plaser = 10W, Parm = 24kW. If we improve T_IMC * T_FI to 90%, then the overall gain becomes x4000, so 10 W from the laser becomes 40 kW in the arms.
- What should our PMC Finesse be so that its barely enough to satisfy filtering reqs and transmission efficiency?
- Suppress angular modes by XX (note that the IMC also filters the beam jitter)
Suppress laser noise at the 11 & 55 MHz readout frequencies by XX (this is primarily a PMC function as the IMC transmits the sidebands)
Maintain a T_PMC > 0.9X (if the existing spec is accurate, the best possible T is ~88%)
- What's up with our T_IMC ?
- let's clean the IMC mirrors
what's the MM frac between PMC and IMC? Judging by the IMC visibility, this is ~98%.
- Is our T_FI too low?
- measure this during the vent when we clean the IMC
- What is the loss in the PRC?
- clipping in the PRC
- new PR/SR mirrors
