On site: Suzanne, Piernicola, Manuel

Remote: Luciano, Ilaria

This morning, we performed HWS-INJ acquisitions to measure the optical path variation induced by the CO2 PA.

The HWS-RC acquisitions were done for different CO2 PA positions. 
Before starting, we moved the CO2 PA in the opposite direction wrt the Position 2 described in the entry 68291, we will called it Position 4 (see fig. 1).  

We started by applying approximately 40 mW, instead of the 50 mW used in 68291.

Position 4   

The HWS-INJ SLED ON at 1.63 V.

The CCD illumination is shown in Figure 2. 

ITF configuration: LN2 achieved at 09.20 UTC

Start acquisition:  09.56 UTC (Folder 20251203T1056)

IPATSiA ON: 10.01 UTC (WF 13)

Unlock at 10.07 UTC (WF 26)

IPATSiA OFF: immediately after the unlock

HWS-INJ acquisition stopped at WF 27.

The CO2 PA immediately appears in the HWS-INJ map (see Fig. 3). For convenience, the same figure also shows the HWS-INJ image with the YAG on the WI mirror.

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Since the impact of the CO2 PA was destructive and the ITF unlocked very quickly, we decided to move the CO2 PA to Position 1 described in entry 68291, as in this position the ITF was able to maintain the lock.

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Position 1-HP (the same Position 1 as during Monday’s shift)

ITF configuration: LN2 AT 10.39  UTC

Start acquisition:  10.50 UTC (Folder 20251203T1150)

IPATSiA ON: 11.01 UTC (WF 29)

Unlock at UTC 11.05 (WF 41)

HWS-INJ acquisition stopped at WF 42.

The CO2 PA immediately appears in the HWS-INJ map (see Fig. 4). 

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Again, the ITF unlocked very soon. So we decided to decrease the power injected up to 10 mW.

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Position 1-LP (same as before, but with 10 mW of injected power)

ITF configuration: LN2 achieved at 15.30  UTC

Start acquisition:  15.44 UTC (Folder 20251203T1643)

IPATSiA ON:  15.48 UTC (WF 12)

The CO2 PA immediately appears in the HWS-INJ map (see Fig. 5).

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Without closing the flip mirror, at 16.32 UTC (WF 129), we moved the CO2 PA in Position 4-LP.

After half an hour (at 17:03 UTC, WF 212), the CO2 PA was moved in the same direction as before by the same number of steps (10000) [POSITION 5-LP].

After another half hour (at 17:36 UTC, WF 300), the CO2 PA was moved again in the same direction by the same number of steps (10000) [POSITION 6-LP].

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IPATSiA OFF: 18.07 UTC (WF 383) [FLIP MIRROR CLOSED]

The HWS maps for each data set are summarized in Figure 6.
Then, Piernicola went to the CEB to switch off the entire IPATSiA setup (laser+CH).
He came back at 19.08 UTC / activity concluded.