I have long been concerned about the IO High Power Beam Dump (IO HPBD) at the North End of the PSL table, and it's cooling hoses hanging down from the beam dump, as a source of PSL table vibration.
I talked to Jason about doing a quick test, buy putting strain relief on the IO HPBD, and then looking at the PSL accelerometers. The hoses are taped the side of the NE corner of the PSL table, wrapped in foam, so no direct contact with the table, and the hoses are not touching each other.
The results are clear, this change reduced the accelerometers broadband noise, and eliminated peaks in the Periscope accelerometers at 413Hz. There are some peaks and broadband noise that increased, but I'm not worried about that, since we literally used tape, and the decrease and elimination of other peaks shows that careful strain relief of cooling lines will have a positive effect on the PSL table motion.
The IO HPBD also needs a better mount, as it's a very heavy component, made from metal plates and SiC plates, and currently it is mounted with a post and fork clamp.
No a bad result, for three pieces of tape, a small bit of foam.
Plots show power spectrums for all PSL ACCs, and coherence between the Periscope X and Y ACCs and the table Accs.
In the plots, all data from yesterday, 10/15, at 19:17UTC are shown in black, and data from today, 10/16, at 19:17UTC are shown in colors other than black.
- Jason, Cheryl
Neat result, and thanks for the description and plots!!
Would it be too much to ask for a before photo and after photo overlaid onto a plot of the most insightful channel(s), with clear before/after labels? I am having trouble sifting through the >10 plots and trying to make sense of the various channels and states - some plots that I would expect to see no peak I see peaks, and I suspect I am just misinterpreting the state of the system when the data was captured.