Today, Yannick Petrilli removed 5 concrete bars (5-9) from the ThomX housing roof in order to let the optical table be installed on Wednesday with the help of Bovis and Symetrie.

The safety net above the equiments has been removed too (one had to remove the hooks on one side to be able to slide the net).

One steel guiding cable (on the right side of the picture) is still there "in the middle" and has to be removed before Wednesday.

This morning the Bovis company moved the optical table from the optical room to the Igloo without any problem.

The table is now stored inside the Igloo, just after the large entrance doors, on the right side.
It has been covered with plastic blankets.

Operations before moving the optical table from the optical room to the Igloo.

— the cavity has been filled with clean nitrogen to reach ambient pressure.
— the two valves have been closed using 5 bar air pressure to properly clamp them.
— the dummy tube between the 2 vessels has been removed and the 2 bellows have been protected with plastic covers.
— all the vacuum equipments have been disconnected from the cavity (only turbo and ionic pumps still remain).
— all the optical elements have been removed from the optical table (only some plates and empty mounts still remain, fixed on the table).
— all the electric cables have been removed when possible. Cables for cavity motors are difficult to disconnect from the vessel side due to the housing. They are still in place. Cables which cannot be removed have been fixed with adhesive tapes and/or clamps.

The optical table is ready to be moved by Bovis on the 26/02 to the Igloo.
 

19/06/2020

The first part of the edge installation was on done by Yann and Ronic
- close the 2 valves of the cavity
- stop the ionic pump on the edge side
- go to ambient pressure with the special filter
- install the edge on its moving arm
We stopped the installation because of a problem with the flange screws which are touching the moving arm structure => Yann modified the moving arm structure.

01/07/2020

Today, Titouan and Yann finished the installation of the edge in one of the vessels of the FP cavity (the vessel which does not contain the input mirror).
they fully cleaned the arm which holds the edge and goes inside the vessel to cut a part of the cavity beam to block the high order modes.
after closing the vessel, they start the primary pumping:

primary vacuum   : 8e-2 mbar
pumping duration : 1h30.

and then, they start the turbo pumping:

turbo vacuum : 6e-6 mbar
pumping duration: 2h30.

Tomorrow, they plan to wait to have a vacuum level, compatible with ionic pumping (below 1e-7 mbar), to start the vacuum ionic pump (only on the "edge side") and stop primary and turbo pumping.
the question is: what is the tolerable vacuum difference between the two parts of the cavity, to open the valves?
one has to ask the vacuum group for that.

02/07/2020

This morning, after a night with primary pump + turbopump on, the vacuum was between 1e-6 mbar and 2e-6 mbar.
at the end of the day, the pressure was still the same... it is the turbopump limit more or less.
Then, I started the ionic pump WITH protection ON, several times.
each time, the pressure increases a lot (to 1e-5 mbar) as the ionic pump releases particles, and then the protection stops automatically the ionic pump.

the ionic pump was started several times WITH protection ON until the maximum pressure is below 5e-6 mbar, then I remove the protection of the ionic pump to let the pumping process going below 2e-6mbar.
NEVER let the ionic pump without protection if you don't stay beside to stop it in case of.
once the pressure is below 2e-6 mbar, I put back the protection and the ionic pump HV is increasing to 7kV and the pressure is going down.
after 1h of all pumps working:

5 pm: pressure is 1.9e-7 mbar

Then, I closed slowly the valve between the turbopump and the cavity (the primary pump is still ON) and stopped the turbopump.
now, the ionic pump is pumping alone the cavity.

6.30pm : pressure is 1.3e-7 mbar

03/07/2020

This morning, I closed the valve of the primary pump, pumping the edge side, and stopped it.
8 am: pressure is 7e-8 mbar (on the edge side).

the other side of the cavity, closed by 2 valves, was around 1.3e-9 mbar.

3 pm: pressure is 6e-8 mbar (on the edge side).

The problem is to open the valve between the tube (which was not pumped for 2 weeks) and the "edge" vessel which was pumped by the ionic pump (6e-8 mbar).

With Frederic, we just stopped the ionic pump (the vacuum increased a little bit) and directly opened the valve on the edge side.
the vacuum raised above 1e-6 mbar and then we restarted primary and turbo pumps until we reached a level below 1e-6 mbar.
then, we switched on the ionic pump again and stopped turbo and primary pumps.

Now the edge side AND the tube are pumped together with the ionic pump alone.
Frederic advised me to tighten a little bit more the screw of the valve of the turbopump to avoid any leakage.

4 pm: pressure is 5.2e-8 mbar

Frederic changed the configuration of the ionic pump controller from "fixed HV" to "stepped HV" to adapt the HV to the level vacuum (if the vacuum is good enough, the HV is automatically decreased from 7kV to 5kV or 3kV to improving pumping efficiency).

Frederic mentioned also the possibility to use mass spectroscopy installed on the cavity to make some leakage measurements with a Helium bottle.

06/07/2020

Today, after pumping all the week-end with the ionic pump, the vacuum was 1.5e-8 mbar.
I opened the second valve and the vacuum changed to 1.2e-8 mbar.
Now, the cavity is completely open and pumped by the 2 ionic pumps.

07/07/2020

09:00 am: pressure is 7.3e-9 mbar
16:30 pm: pressure is 7e-9 mbar

08/07/2020

09:00 am: pressure is 6e-9 mbar

10/07/2020

11:00 am: pressure is 4.2e-9 mbar

13/07/2020

06:00 pm: pressure is 3.2e-9 mbar

15/07/2020

04:00 pm: pressure is 2.8e-9 mbar

A new circuit breaker has been installed today before the UPS to fix the shutdown issues we observed some months ago when too many devices are connected to the UPS.
it has to be tested...

The Pneumatic valves are still coming back to "close" position.
Now the air bottle is always "open" to keep the valves "open".

The 30Hz noise is still here. We tried to cut off all the air flows. It only decreased the noise intensity but didn't change its shape.

21/11/2019 :

The pneumatic valves are now connected permanently to the university airflow network.
there is a small air leakage but it is not an issue anymore.

the 30Hz noise has been fixed too as it was coming from the extreme position of M1 and M4 (plan mirrors) and due to mechanical instability in this position (motor "outside")

Today, Manu and Eric changed the cavity valves pressure system to open and close them.

during the lock of the OneFive+Amp or of the Koheras, we saw a very noisy PZT signal at 30Hz with increasing/decreasing amplitude very slowly.
this noisy signal was not seen at the begining of the experiment.
as it is independant of the laser source, we guess it should come from the cavity.
at this moment, one only see these valves (which tend to close by themself when there is some leakage) as a source of frequency noise.
we will see if, with this cabling change, the noise on the PZT signal changes also.

Scheme of cabling of the SmarAct motors controllers for acting on Frep and CEP.

Today, the chiller worked at 17°C during 3 hours without error, no freezing nor flow sensor error.

We observed 2 issues for the chiller of the new CELIA laser amplifier:

• setting the water temperature to 17°C, the chiller water turns to ice close to the water filling port !!! => temperature too low ?
• even when the water is fluid, one has a flow sensor error ! => pump charge too strong ? => reduce the water pipe length.

We have set the water temperature to 20°C and we shortened the water pipes by 2-3m

         => both problems seem to be fixed.

Now, we can try to reduce the setting temperature.