Virgo Logbook

AdV-TCS (Point Absorbers Mitigation)

melo, spinicelli, nardecchia, bersanetti, ruggi - 23:30 Thursday 26 June 2025 (67142)

Shift on IPATSiA setup

Today we continued the work on the IPATSiA setup (#67057).

We arrived around 18.15 LT at WE. At 18.30h LT we switched on the chiller and the laser and waited a bit for thermalization. The power was oscillating a bit between 30 mW and 45 mW.

Here a chronological list of the events (see Fig. 1):

At 19:42 LT the ITF locked in LN2:

19:45:15 -> START SHINING
20:06:30 -> STOP SHINING (Fig. 1 red bars)

At 20:17 we changed the position of the point absorber. The power was stabilized at 28 mW.

20:39 -> START SHINING
21:00 -> STOP SHINING (Fig. 1 orange bars)

At 21:02 the ITF unlocked and we changed again the position of the PA. At 21:50 the ITF relocked in LN3.

21:51:15 -> START SHINING
22:09:30 -> STOP SHINING (Fig. 1 yellow bars)

At 22:15h we raised a little the emitted power of the CO2 laser to 41mW.

22:25:30 -> START SHINING
22:51:15 -> STOP SHINING (Fig. 1 green bars)

At 22:55h we swicthed off the CO2 laser and then the chiller at 22:57h. The power setting has been left to 41 mW (not the minimum).

Images attached to this report

Comments to this report:

melo, spinicelli - 12:27 Friday 27 June 2025 (67149)

Here we put the some thermocamera pictures for, respectively:

the background with not beam
Position 1 (LN2, GPS 17.45UTC)
Postion 2 (LN2, GPS 18.39UTC)
Position 3 (LN3, GPS 19.51UTC)

The TIFF files are available if needed.

Images attached to this comment

mwas - 21:19 Sunday 29 June 2025 (67164)

The point heating with IPATSiA has changed slightly the position of the HOM in the FSR.

Figure 1 shows the order 2 peaks, these move up in frequency slightly, add additional peaks at higher frequency either appear or become more prominent

Figure 2 shows the order 6 peaks, these move down slightly, and additional peaks at lower frequency either appear or become more promintent .

Figure 3 and 4 shows the same as an ASD, comparing the time with IPATSiA off (purple) and on (blue).

The fact that additional peaks appear can make sense, adding a heatpoint will make the mirror astigmatic, as the heatpoint is not perfectly centered.

The fact that the order 2 and 6 modes move in opposite directions is surprising. The same had happened when the ring heater power was changed https://logbook.virgo-gw.eu/virgo/?r=67078 . I do not have an explanation for this.

Images attached to this comment