Reports until 14:37, Saturday 10 January 2015
H1 SUS (SYS)
brett.shapiro@LIGO.ORG - posted 14:37, Saturday 10 January 2015 (15995)
All SUS and all stage temperature sag predictions

Motivated by the rubbing saga of ETMX (15985), I have compiled a list of how much each stage of each suspension sags with temperature. This log is just like LLO 15636, except that instead of just top masses, all the stages are included here. The derivation of the temperature sensitivity is in LLO 12581.

 

Table 1: Vertical sag with temperature (microns / C)

Stage QUAD BS HLTS HSTS OMC TMS
1 (top mass) -106 -38 -37 -62 -50 -88
2 -182 -57 -60 -96 -64 -129
3 -223 -58 -60 -96 -- --
4 (test) -224 -- -- -- -- --

 

These numbers were calculated using the derivation in LLO log 12581. The formula from that log is 

    dz/dt = -254*m*g/K    [microns / C]

where m is the total suspend mass of a given SUS stage [kg], K is the total vertical stiffness supporting that mass [N/m], and g is gravity [m/s^2]. The negative sign indicates a drop in height with increasing temperature. The thermal sensitivity of the young's modulus of maraging steel is given by "The maraging-steel blades of the Virgo super attenuator." Braccini et al, Meas Sci Tecnol 11 (2000).

 

Table 2: Relevant SUS parameters

Spring properties QUAD BS HLTS HSTS OMC TMS
Stage 1 mass (kg) 123.32 40.42 36.46 8.99 10.02 123.94
Stage 1 stiffness (N/m) 2889 2684 2437 360 500 3519
Stage 2 mass (kg) 101.32 27.79 24.37 5.87 7.12 79.86
Stage 2 stiffness (N/m) 3333 3540 2689 439 1229 4847
Stage 3 mass (kg) 79.32 14.21 12.14 2.89 -- --
Stage 3 stiffness (N/m) 4875 83213 189190 43139 -- --
Stage 4 mass (kg) 39.64 -- -- -- -- --
Stage 4 stiffness (N/m) 72139 -- -- -- -- --
Parameter file quadopt_fiber bsfmopt_glass hltsopt_metal hstsopt_metal omcsopt_metal tmtsopt_production