Sheila, Vicky, Georgia
Today we started beam profiling in HAM7. After some difficulties (alignment sliders for the ZM's reset to 0, ZM3 watchdog tripping, OPO temperature needing tuning, ZM1 longitudinal damping loop going a bit crazy, P-SAMS piezo voltage being reset to 24) we were able to get a pretty stable beam from the OPO, reflected off FC1, and back to the ZM4 -> ZM5 -> HAM5 beam path. We had some problems with clipping in yaw on the VOPO platform but were able to find a good alignment by dithering the ZM1 and steering ZM2 and ZM3 the maximize the power and minimize the dither coupling to our monitor diode on SQZT7. The beam looks pretty well-centered on the iris on HAM7 and looks good on the HAM5 gate valve (centered in yaw, low in pit).
The final alignment slider values are:
We took some beam profile measurements of the beam reflected off ZM5, on the -X side of the chamber, which we previously did using the retroreflected beam. The profiler was 259mm from the edge of the ISI (see attached photo an idea of where it was, sorry it's out of focus!)
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ZM4 [V]
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ZM5 [V]
|
ZM2 [V]
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w_x 13.5% [um]
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w_y 13.5% [um]
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w_x D4s [um]
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w_y D4s [um]
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ZM2 SG [V]
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ZM5 SG [V]
|
|
100
|
0
|
100
|
1905
|
1679
|
1943
|
1769
|
2.24
|
-
|
|
100
|
0
|
80
|
1837
|
1651
|
1927
|
1926
|
2.0
|
-
|
|
100
|
0
|
60***
|
1705
|
1524
|
1892
|
1679
|
1.7
|
-
|
|
100
|
0
|
90
|
1873
|
1668
|
1935
|
1736
|
2.09
|
-
|
|
100
|
0
|
116
|
1940
|
1772
|
1973
|
2013
|
2.50
|
-
|
|
50
|
0
|
100
|
1782
|
1577
|
1824
|
1720
|
2.31
|
-
|
|
0
|
0
|
100
|
1620
|
1466
|
1667
|
1591
|
2.31
|
-
|
|
100
|
0
|
100
|
1902
|
1652
|
1933
|
1795
|
2.31
|
-2.55
|
|
100
|
50
|
100
|
2063
|
1788
|
2094
|
1947
|
2.30
|
-1.48
|
|
100
|
100
|
100
|
2337
|
2031
|
2364
|
2190
|
2.30
|
-0.17
|
|
100
|
100
|
80
|
2317
|
2073
|
2389
|
2165
|
2.03
|
-0.17
|
|
100
|
100
|
116
|
2326
|
2075
|
2350
|
2303
|
2.49
|
-0.17
|
Some notes:
- When ZM2 is <60V the beam is too large and starts clipping on the VIP.
- We haven't got measurements of the ZM4 strain gauge since I still need to implement Luis' fix for that.
- We originally thought ZM5 was at 100V for the first measurements shown here, but I had left it unplugged at the chassis, so it was very much at 0V.
Georgia mentioned that we had some difficulties above.
- Some of our problems were from things not being saved in SDF.
- I found the SAMS channels in H1TCS and saved the current voltages (100V ZM2, 100V ZM4, 116V ZM5).
- We should move the ZM4/5/6 (which are confusingly called SQZOUT) SDF link to HAM7 on medm, they are currently shown in HAM6 although the suspensions are in HAM7+5.
- I saved the alignment offsets for the ZMs.
- There is apparently a 16 count 1 Hz sine wave coming to all the ZM1/2/3 lock P+Y filters, this was causing the ZMs to swing. The link from the sitemap to the screen for the SQZ_ASC_FC screen doesn't work, but we should follow up and turn that off. For now we've turned off the LOCK filter inputs in the suspension screens.
- ZM3 tripped many many times, we rasied the RMS watchdog threshold to avoid this.
- We may want to take a look at the ZM damping loops. According to the osems they were taking about 30-45 seconds to recover from small disturbances when Vicky was doing even gentle things in the chamber.