Reports until 11:14, Tuesday 03 January 2017
H1 PSL
jason.oberling@LIGO.ORG - posted 11:14, Tuesday 03 January 2017 - last comment - 14:44, Tuesday 03 January 2017(32918)
H1 PSL After the Holiday Break

J. Oberling, P. King (from Pasadena)

Checked on the PSL this morning, all was fine except we lost ~10 W of power over the break (before the break we were at ~160 W, this morning we were at ~150 W) and the NPRO noise eater needed to be reset.  Everything looked as expected, so the power loss is most likely due to natural decay of the HPO pump diodes.  I increased the HPO diode currents to recover our lost power; the currents were changed from 50.5 A to 51.0 A for each HPO diode box.  I then tweaked the pump diode temperatures, see the table below for a summary of the changes (remember that each HPO diode box has 7 individual laser diodes).  The PSL is now outputting ~166.5 W from the HPO box itself (the internal power reading is ~212 W).

 
Operating Temperature for HPO Pump Diodes

 
Diode Box 1 Diode Box 2 Diode Box 3 Diode Box 4
Old New Old New Old New Old New
D1 26.0 25.5 20.5 20.0 22.5 22.0 25.0 24.5
D2 26.5 26.0 20.0 19.5 26.5 26.0 22.5 22.0
D3 28.5 28.0 21.0 20.5 26.5 26.0 24.0 23.5
D4 25.0 24.5 19.0 18.5 23.5 23.0 22.5 22.0
D5 27.0 26.5 19.0 18.5 27.5 27.0 24.5 24.0
D6 26.5 26.0 19.5 19.0 22.0 21.5 24.5 24.0
D7 24.0 23.5 20.0 19.5 23.0 22.5 24.5 24.0
 

With the ISS off this gives 80 W incident on the PMC, which is the desired incident power for the PMC; the PMC was outputting ~65 W.  I then did a quick tweak of the beam alignment into the PMC, only tweaking the horizontal alignment (vertical looked fine), which improved the PMC transmitted power to ~67 W (ISS still off).  With the ISS turned back on the PMC is outputting 64.7 W, which is where it was set at the start of O2.  Also with the ISS on, the FSS RefCav TPD is reading ~3.6 V, so no adjustment is necessary there.  The H1 PSL is ready for the resumption of O2.

Comments related to this report
jason.oberling@LIGO.ORG - 14:44, Tuesday 03 January 2017 (32928)

Attached is a 14 day trend of the NPRO, FE, and HPO laser powers.  As can be seen, the only power drop is seen in the HPO, lending evidence to the power loss being due to natural decay of the pump diodes.

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