An Initial cleaning of the KBoX outside was done, All the optics and mechanics placed that were on the table were removed.

Only the old Mitylaser amplifier remains on the table.

Since we will be using the ThomX Celia amplifier, we will remove it and place it in a secure location (to be decided).

Tomorrow a cleaning of the inside of the cavity box is to be done.

The cleaning was done twice with half an hour interval between the two times
reading on the dust meter was taken after each time, and it was zero averaged over a 10-min

In preparation for cleaning the mirrors.

The spincoater has been moved with its bump into the sas of the SBox.

The pure water used will be provided by Alice, as the previous source in the workshop is not available.

The chiller of CELIA amplifier has been moved from the corridor to the changing room in front of PLIC. 

It was not functionning well (quick drop of flow below 0.9l/min). After several cleanings of the filter, shorting the water circuit a stable 2.1l/min flow was obtained. Then the water circuit was elongated to go close to the amplifier but not into it. Allowing to get about 1.3l/min stable. Now the amplifier is conencted, the filter has been cleaned again twice and the flow seem stable with 1.4l/min. New filters have been ordered and must arrive quickly. Changing it is necessary I think. 

today, temperature of the chiller has been set to 23°C.

measured temperature in the chiller reaches 23°C after approximatively 10 minutes

this morning with Alice and Daniele, we removed all the optics elements and equipments from the SBOX optical table and started to clean it.
the dust meter count 0 on all particle sizes after the cleaning.

we observed a small part of the SBOX which seems to be oxydised (see picture).

the two previously used mirrors of the SBOX (C23018/7 and C23017/2) were already in their plastic boxes outside of the SBOX.
they are still on the optical table.

we have to decide which mirrors to put in the cavity:

if we don't want to use a "new" ThomX coupling mirror M1, we have to use a Gamma-factory mirror (161185) with T=460ppm for example (we don't have any other FS plan mirrors).

if we don't plan to work at high power in the SBOX for the moment, we could use an "old" ThomX M2 mirror with ROC=2.241m (C1611/11) to avoid any risk of contamination of a "new" ThomX M2 mirror.

this afternoon, we checked the dust meter which is at 0 for 1 and 5µm dust particles but ~ 2000-3000 for 0.3µm particles.

we opened the two top panels to let the air flow clean the inside of the vessel.

we observed some other minor oxydised regions (than the one taken in picture) on the external parts of the inox panels but at first sight, nothing inside the vessel.

now, it seems the table is clean enough (dust meter counts 0 particles) to install a 2 mirrors FP-cavity.

The inside of the cavity was cleaned today. It was very dirty and had big dust particles and fibers inside.

Cleaning was done for everything; wall, floor, fixed mounts, wires (still have some dust difficult to remove), edges.

The dust meter average was measured outside the cavity (2471 p/m3 av 6 min)  and inside after cleaning (1424 p/m3 av 10 min).

The cavity was left open under the clean air flow, will observe it under UV, clean and measure Dust tomorrow.

Images attached are after cleaning.

Objects inside the cavity at the moment :

• 4 main mirror mounts
• 4 mirror fixers on mounts and 3 screws each (total 12)
• 2 reflecting mirror mounts
• 2 dielectric mirrors (mounted and to be cleaned)
• two mounts for D-shaped mirrors.
• 2 D-shaped mirrors (unmounted, and they will need cleaning)
• 2 metal irises (pinholes)

After an overnight where the cavity box was left open, a measurement of the Dust meter was taken:

Outside on the optical table on direct air flux (1701 p/m3 Av 10 min) and

Inside the cavity box (998 p/m3 Av 10 min)

The dust inside the cavity has decreased by ~ 30 % for 0.3 u particles.

Note: the cavity box is still open.

from the begining of the week, Xinyi, Aurélien, Viktor and myself started to install a new setup for the Menhir 160MHz oscillator.
the goal is to rich a record power in the FP-cavity.

- the 160MHz Menhir oscillator has been injected in a fiber.
we reached ~ 25mV on 50ohms which is equivalent to 0.5mA in a DET10 photodiode.
=> ~1mW coupled in the fiber => it is not enough to put an EOM and an AOM before the amplifier.
=> one needs to improve the fiber injection.
in fact, I checked the power in the fiber with a powermeter, and it is ~16mW !
at this level of power, one needs to add some optical density before connecting to a photodiode, or it can be saturated.

- we calculated the mirrors position in the SBOX vessel to obtain a 160MHz FSR FP-cavity.
see in attached files, the calculations and scheme in the PPTX file and the Matlab code to get some results.

- we cleaned the optical table and verified with the dust counter that the SBOX environnement is clean.
the 2nd airflow box (from the entrance) seems more dusty (measureed directly close to the top) than the others.
we also opened the vessel and cleaned it.
see the dust measurement inside the SBOX.

- we checked the motors inside the vessel :
=> spherical and plan mirrors translation stage control with the ESP300.
the translation stage have been placed on the middle of their range.
=> the 2 D-shape mirrors translation stage control with PICOMOTORS controller Newport 8742.

- today, Viktor and Xinyi should start the installation of the mirrors mount and make some test to check if the beam is properly propagated inside the FP-cavity, before installing the final mirrors.
the mirror mounts are the Newport SU100TW-F2K zero-drift low waveform distortion : https://www.newport.com/p/SU100TW-F2K
they can accept mirrors with 6-6.35mm thickness => normally the SBOX mirrors from the LMA have a 6.35mm thickness.
see 1st file from this post : https://elog.lal.in2p3.fr/FPC/SBOX+commissioning/174

The SBox Length (FSR), was changed to match the repetition rate of the Menhir pulsed laser Frep = 216.6625 MHz

It was changed by removing the 2 D-shaped mirrors placed between M1 and M2, distance between M1-M2 ~= 169 mm 

it was still needed to be adjusted with M1 motor to reach the correct FSR.

The pulsed laser is placed on the able with injection into a fiber

The Finesse of the cavity has progressed from ~2500  to ~ 18 000

** Note: PowerPoint attached shows the progress over the last two weeks on the laser and 

This afternoon we opened the cavity and put the D-shape mirrors at their correct place, close to the beam.
we checked the relative position of the mirrors to the beam using the 2nd stage of the amplifier (<1W) and with the sensitive (and cleaned) orange optical card.
with this configuration, we can see very clearly the beam inside the cavity (~ 100µW) and we can check easily if the D-shape mirrors are correctly placed.

the motors used to move the D-shape are the Newport Picomotors 8303-V
with roughly 30nm/step sensitivity and 50mm of range (~1 600 000 steps)
the 4 axis controller used ot move these motors is the Newport 8742.

For both Vertical and Horizontal D-shape mirrors:
* when you do +N steps on the controller, you retract the D-shape mirror from the beam
* when you do -N steps on the controller, you push the D-shape mirror to the beam

the 0 position on the controller corresponds to the D-shape close to the beam.

now, the FP cavity is closed and pumped to go back to vacuum.

The cavity box is vacuum pumped at 6*10^-2 mbar.

summary:

- the motors used to move the D-shape are the Newport Picomotors 8303-V
the sensitivity is roughly 30nm/step
the range is 1 600 000 steps or 50mm

- the 4 axis controller used ot move these motors is the Newport 8742.
channel 1 is for the vertical D-shape
channel 2 is for the horizontal D-shape
+N steps on the controller, you retract the D-shape mirror from the beam
-N steps on the controller, you push the D-shape mirror to the beam

the 0 position, vertically and horizontally is close to the beam.
the stand position is at ~ +200 000 steps in both directions.

With Alice, we installed the EOWaves oscillator to be locked on the FP-cavity (T1 ~ 2500ppm, T2 ~ 10ppm => F ~ 2500)
FSR = 216MHz => LW = 86kHz.

We installed the PDH box, and we got some error signal, but the shape of the transmission signal and error signal is a bit strange...
It grows smoothly, and when the power is large enough, one can see a sudden and fast drop.
Could it be some mechanical problem with the mirrors' mounts ?
I opened the SBOX this morning to do some inspection, and the mirrors seem properly installed in the mounts.

In some rare cases (last picture), the "instability" effect is not dominant, and we are able to maintain a quasi-lock during some 1- 2ms.
But it is still impossible to lock the cavity.

(We did a test with a vacuum in the SBOX at ~2mbar, but the problem is the same.)

we have all the adaptor plugs for connecting the chiller.
so, I tested first the chiller connected in closed loop (on itself).

there is no manual, so procedure is not completely clear...

DO NOT PLUG ANYTHING BEFORE THE CHILLER ASK FOR IT
ONE MUST FOLLOW THE PROCEDURE ON THE CHILLER DISPLAY

1) if the chiller circuit is full of coolant liquid,
one must start by a System Startup -> Draining
(a trash tank and the hose will be need for emptying the circuit)

2) once the chiller circuit is empty
one must continue by System Startup -> Filling
(a clean demineralized water tank and the hose will be need for filling the circuit)

=> OK !
the chiller is able the fill and drain its circuit.
I saw the cooling water circulating in the closed loop.

now, I connected the chiller circuit to the amplifier, thanks to the adapters.

chiller IN => blue pipe => laser OUT
chiller OUT => black pipe => laser IN

after several filling and compression procedure, the flow is only 1.7Lpm and the pressure is 0.8 bar.
the temperature has been set to 20°C according to the manual operating range 18-23°C. 

the flow is too low !
according to the manual, the flow should be 3-5Lpm !

a very small leakage appears if the mechanical constrains on the pipe is too high.
so, I separated the IN and OUT pipes to release this constrain and fixed the pipes to keep the position.

pipes are maybe too long ?

we can use the Darcy-Weisbach + Blasius laws (non linear laws).
I asked to ChatGPT, Claude, Mistral and MathGPT to solve it with these parameters :

L ~ 3m
D = 1 cm
water at 20°C
dP = 0.7 bar

they all found ~ 22-23L/min

so, the tube length should not be the problem... to be investiguated.

I drained the chiller to install again the short pipe (< 1m) in closed loop.

then, I filled again the chiller and did the compression process to obtain 1bar.
in that case, the flow measured by the chiller is correct about 5.8Lpm.

PS : the correct length for the previous calculation is 6m (2x 3m) and not 3m...
in that case, the flow should be ~ 15Lpm (and not 22 Lpm)