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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: 1056     Entry time: Thu Oct 4 23:28:06 2012     In reply to: 1054     Reply to this: 1058
Author: tara 
Type: Notes 
Category: RefCav 
Subject: comsol simulation for cavity suspension 

I'm using COMSOL to simulate the effect of cavity sagging to find the optimum suspension points. The answer is not yet ready, I'm still working around COMSOL.

 

  • Problem with point like contact: First I tried to simulated 4-fixed-point support, however the result was asymmetric along beam line. It might be the result from the point-like contacting areas between the support and the cavity. You can see the tilting along the beam line in the figure below. Note the constrained area  of the support effect the sagging slightly as well [add ref].

.cavity_sagging_0_2012_10_04.png

fig1: cavity sagging, on 4 point suspension. The cavity is not symmetric on left and right.

     So, as a start, I switched to half line support. As my cavity support will be rods placed perpendicular to the refcav, the simulation might not be off by much. Then I checked the displacement at the center of the mirrors. The result was, the further to the ends of the spacer, the less displacement of the mirrors. I think this is strange. I also remember a paper about this and their cavity dimension is similar to what we have, and their result is slightly away from the ends [ref]. I'll have to double check the result again.

Note: I think what is wrong is how I use the displacement of the mirrors along the beamline as differential length of the cavity, I have not taken into account tilting of the mirrors yet. Also, I'll try to position the venting hole downward to see if there is any differences in the result or not.

 cavity_sagging_2012_10_04.png

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