Virgo Logbook

AdV-INJ (Suspended injection bench (SIB1) body)

derossi, pillant, magazzu', genin, ruggi, vacuum team - 18:47 Monday 26 February 2018 (40678)

SIB1- IPC2 upgrade

Last Friday we started the upgrade of SIB1 bench, consisting in:

- Brewster polarizer replacement. We replaced the polarizers of the IPC with three polarizers from LMA, having less reflection losses (~0.3% the first two and ~0.4% the last one), as shown in fig.1.

- Installation of a polarization rotator. A half-wave plate has been installed between the first and the second polarizer.

- Installation of a Peltier element. We installed a Peltier module on the path of the beam reflected from the third polarizer, as shown in fig.2. It will be used as a passive element to monitor the power of the beam injected into the ITF (Datadisplay channel INJ_SIB1_PELTIER). Its characteristics are: 40mm x 40mm, 58.6W, 6A, 15.7V . Furthermore, in order to avoid scattered light, we placed on it an AR coated steel baffle.

- Replacement of the PSTAB box. Last friday we removed the electronics box from the filter 7 cage, the vacuum group has changed the indium seal, we installed it today and we checked that the signals make sense. We noticed some strange values of the pressure and temperature sensors. We will check and report it in a further logbook entry in the following days.

After these operations we suspended again the bench and we made fine balancing. The total weight added on the bench is 263 g. Details are given in the table below.

removed	half waveplate + mount	- 429 g
-	beam dump + support	- 164g
installed	New half waveplate mount + cable db9 to lemo 2 pins X2	+ 298g
-	peltier+copper holder+baffle	+ 531 g
	total added weight	+ 263 g

Images attached to this report

Comments to this report:

genin, nenci - 11:49 Tuesday 27 February 2018 (40685)

Today we checked the temp probe and pressure probe signals at the level of the patch panel in the CB entrance and we measured:

V_Te=0.394V (0.317V read with datadisplay). There is a problem here which has to be understood.

V_Pressure=1.49V (1.45V read on datadisplay)

For the temperature, the formula to convert the voltage in temperature is:

TE=200*V_TE (in V)-50. Thus the temperature in the box is now 28.8C.

For the pressure, the formula is:

Press(kPa)=22.22*V_Pressure (in V)+10.556.

We find 43kPa which is far from the expected 100kPa or 1bar (the box has been opened and closed yesterday by the vacuum group after having changed the indium seal).

We think there is a problem with the pressure probe. Problem which is likely to be existing before.

Since the tests on the spare electronic box have not been completed yet. We will keep working with this box relying of the temperature monitor.

genin, pillant - 12:10 Wednesday 28 February 2018 (40692)

Today, 1 channel has been created in ISYS_moni to calibrate temperature of the Power stabilization box recently installed.

# power stabilization box temperature and pressure calibration
ACL_ADC_CH PSTAB_TE_C "C" 1 LOOP_FREQ Pstab_TE -50 250 NONE

We used the following formula:

PSTAB_TE_C=200/0.8*V_TE-50. The 0.8 is coming from the losses reported yesterday in the logentry.

The other coefficients in the formula are the standard one reported in the first file (prepared by J.P Coulon).

The signal name is PSTAB_TE_C.

The current value is 32.2C for temperature.

We might be able to create a monitor of the pressure using the temperature sensor once the box will be arrived to thermal equilibrium

(once there will be photocurrent arriving in the box too).

Non-image files attached to this comment

quadvide.pdf