Virgo Logbook

Detector Characterisation (Data monitoring)

fiori, paoletti - 11:17 Thursday 17 January 2019 (44404)

magnetic probes

yesterday we positioned two magnetic probes:

ENV_IEB_MAG_RAPROBE on top of the IMC lock rape auto board in Injection electronics room
ENV_TCS_MAG nearby the TCS rotator drivers in TCS electronics room (see picture)

The plan is to take some data with the ITF locked then (on weekly basis) move them to different locations. Also DetChar shifters are invited to look at these probes and check possible coeherences or correlations of lines or glitches with DARM.

Note: before yesterday and at least since last December (including ER13) the two probes were located: (1) on top of EIB SAS electronics (ENV_EIB_ELE_MAG); (2) at the UPS main switchboard inside TCS room nearby electrical cables powering TCS CO2 chillers (same name ENV_TCS_MAG).

Images attached to this report

Comments to this report:

robinet - 11:42 Thursday 17 January 2019 (44405)

You probably mean ENV_IER_MAG_RAPROBE (typo).

I restarted the Omicron processes to include these new channels.

verkindt - 11:31 Thursday 24 January 2019 (44507)

Plot 1 shows the comparison of Dec 15 2018 and Jan 13 2019 lock periods for what concerns the coherence between the signals ENV_TCS_MAG and LSC_DARM.
Plot 2 is a zoom between 100 and 200 Hz where we can see several differences around 100, 150 and 200 Hz.
Plot 3 is a zoom around 200 Hz, where we can see that there was almost no coherence in December while there is a strong coherence in January.
More generally, January shows a lower noise on ENV_TCS_MAG but a larger noise in LSC_DARM

Plot 4 shows, for January 18, that ENV_TCS_MAG is much noisier than ENV_IER_MAG_RAPROBE, but ENV_IER_MAG_RAPROBE is much affected by a set of 1 Hz comb.
The probe ENV_IER_MAG_RAPROBE is active since January 17 2019. We will compute a coherence as soon as a DARM signal is available.

Images attached to this comment

Paoletti - 13:58 Thursday 24 January 2019 (44508)

It is surprising (at least to me) that this temporary magnetic probe (ENV_IER_MAG_RAPROBE), placed on the cover of the RampeAuto crate, detect quite well all Mode Cleaner Building HVAC machine status.

In the attached plot the correlation with the Current Sensors of IPS MCB mains line (ENV_MCB_IPS_CURR_S) and with the MCB magnetometer (ENV_MCB_MAG_N) is clear.

The last plot (INF_MCB_CHILLER_CURR) is a Current Sensor on the HVAC Chiller machine

Moreover worth noting that when the magnetic field increases in MCB, the same decreases in the magnetic probe positioned on the cover of the RampeAuto

It's difficult to believe in a direct measurement of the MCB magnetic field at a distance of 150 meters with the temporary probe, also for this "out of phase" behavior. Most likely we are seeing an unwanted coupling effect (e.g. ground current through the ModeCleaner tube?).

Is there a way to measure the (AC) current flowing in the pipe? Wrapping a few wires around it and take a look (with a battery powered system)?

Images attached to this comment

verkindt - 15:23 Monday 28 January 2019 (44581)

Plot1 shows a comparison of the signals ENV_TCS_MAG (orange) and ENV_IER_MAG_RAPROBE (blue) for what concerns their coherence with LSC_DARM, in the frequency range 40-400 Hz.
Plot2 is a zoom around 100 Hz where the largest difference is visible.

Images attached to this comment