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