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Entry  Sun Sep 23 18:28:04 2012, tara, Notes, Drawings, 1.45" refcav mount cav_mount_assembly2.PDFcav_mount_assembly2.PDFcav_mount_bottom.PDFcavity_mount_top.PDF
    Reply  Thu Sep 27 17:13:13 2012, tara, Notes, Drawings, 1.45" refcav mount cav_mount_assembly_3.PDFpeek_v2.PDF
       Reply  Thu Oct 4 23:28:06 2012, tara, Notes, RefCav, comsol simulation for cavity suspension cavity_sagging_2012_10_04.pngcavity_sagging_0_2012_10_04.png
          Reply  Wed Oct 10 01:38:49 2012, tara, Notes, RefCav, comsol simulation for cavity suspension 
             Reply  Wed Oct 10 21:31:57 2012, tara, Notes, RefCav, comsol simulation for cavity suspension plot.pngcavity_sagging_0_2012_10_04.png
                Reply  Thu Oct 11 19:07:06 2012, tara, Notes, RefCav, comsol simulation for cavity suspension plot_degree_area.png
                   Reply  Sat Oct 13 23:38:08 2012, tara, Notes, RefCav, comsol simulation for cavity suspension dis_tilt_12_45.png
                      Reply  Tue Oct 16 01:14:00 2012, tara, Notes, RefCav, comsol simulation for cavity suspension disx_y.png
                         Reply  Wed Oct 24 11:16:52 2012, tara, Notes, RefCav, comsol simulation for cavity suspension analyzed_plot.pnganalyzed_plot.figIMG_1914.jpg
                            Reply  Fri Oct 26 04:05:18 2012, tara, Notes, RefCav, comsol simulation for cavity suspension plot_line.pngplot_line.pngplot_line.pngplot_angle.png
                               Reply  Tue Feb 4 01:11:01 2014, tara, Notes, RefCav, comsol simulation for cavity suspension 
                                  Reply  Tue Mar 4 18:53:48 2014, tara, Notes, RefCav, comsol simulation for cavity suspension hist_small_mount_err.pnghist_small_mount_err.fig
       Reply  Wed Oct 31 16:00:13 2012, tara, Notes, Drawings, 1.45" refcav mount Assem2.PDFAssem2_1.PDF
          Reply  Thu Nov 8 20:00:33 2012, tara, Notes, Drawings, 1.45" refcav mount 7x
Message ID: 1067     Entry time: Fri Oct 26 04:05:18 2012     In reply to: 1065     Reply to this: 1405
Author: tara 
Type: Notes 
Category: RefCav 
Subject: comsol simulation for cavity suspension 

I looked into the model a bit more to make sure that I included all the effects and get the coupling right [more to come]

 

plot_line.png

fig1: displacement(beam line direction) per unit acceleration on the mirror surface. X-axis represents the position on the mirror along vertical line. Each plot represents result from different support positions. For optimum point (1.17"), the sensitivity to vertical seismic is around 2.1x10^-12 m/(m/s^2).

plot_angle.png

fig2: This plot shows the result as in fig1, with the means removed. Typically we want the tangent line at the center to be zero for minimum tilt.

 

  1. Now I use SI units in the simulation.
  2. The surface displacement along vertical direction is ~ 5 x10^-10 m. The spot radius is 100 um, so the effect from translation along vertical direction is negligible. We can assume that the beam still hits and senses the center of the mirror.
  3. Check the result between support length between 1.18" +/- 0.02" (+/- 0.5 mm). This tolerence is what I estimate to be our assembly tolerence.
  4. I calculated the tilt by using the tangent line at the displacement on the vertical line in the mirror center. Note that my mirror surface in the simulation is flat instead of curve. At 100 um away from the center, the surface height will change by ~ 10^-8 m due to the mirror's RoC. Meanwhile, the result from simulation (flat surface) shows that the displacement around 100 um away will change ~ 10^-12 m. However, I don't think it will effect our model much, since most of the deformation occurs around the support point, not the mirror. It means all the tilting comes from deformation on the spacer, not the mirror. So the simulation for flat mirror should be a good approximation.
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