Mail de Bruno Mercier du 18/10/2018 :

Un petit CR de la journée:
Nous avons effectué une détection de fuite sur l'ensemble des cavités optiques. Une fuite très importante a été localisée au niveau de la bride de la Pompe ionique (PI) située sur la deuxième cavité optique par rapport à l'entrée de la salle blanche.
Manu a démonté la PI , la fuite provenait du fait que le joint n'était pas tout à fait centré. Après un remontage de la PI, une nouvelle détection a été faite:
détection d'une fuite sur la bride avec les sorties Sub-d M4 après resserrage c'est OK.
Détection d'une fuite sur la bride de sortie DN200 avec  hublots de la cavité 1 après resserrage c'est OK.

Demain et le début de la semaine prochaine sera consacré à la mise en place de l'étuvage, puis de la descente en pression avec pompage ionique.

bonne fin de journée,
Bruno

Mail de Bruno Mercier du 19/11/2018 :

Une première cavité a été étuvée, la pression est actuellement de 
3.10-10 mbar, l' étuvage de la deuxième cavité vient de commencer et se 
finira en début de la semaine prochaine.

Bonne journée,
Bruno

Vacuum tests finished on 19 december 2018.

Spent last two days to discuss the importance of removing aluminium and baking wires before to insert mirrors for cleanliness issues. Finally we took pictures to support our demand.

Cavity should be ready to clean for the new term 2019

Le 19/12/2018 à 14:56, Bruno Mercier a écrit :

Bonjour Daniele, Loïc,

Nous sommes à votre disposition pour effectuer une entrée d'azote sur
la cavité.

Bruno

The cavity is right now at 6.5e-8 mbar (turbo pumps on for 1 night and ionic pumps for 3h), primary pumps and turbo pumps are cut, ionic pump are on and the pressure level is still going down. 
Therefore there aren't any big leak in the cavity and we can expect a final vacuum level close to e-9 mbar.

The pneumatic valves are now plugged on the university air network.
The air valve is fully openned for the moment.
We still have to check if there is some minor leakage close to the pneumatic valve to improve the setup.
But it's not anymore an issue for the lock.

Last Friday and this morning, with Bruno, we close the ring/cavity valves and put some dry air in the two vessels through a filter to avoid turbulences.

Now, the two vessels are at ambient pressure and ready for opening (to remove the mirrors).

One can let the ambient pressure in the vessels as long as we want, the ring/cavity valves have been chosen to be compatible with the high vacuum in the ring and the ambient pressure in the vessel for a long time.

08/02/19 - End of the cleaning process.

All the equipments have been switched off on Friday 17th due to a power shut down on Saturday 18th :
CW and Onefive oscillators, computers, laser amplifier, cavity mirror motors, chiller, etc...

Today, I restarted all the equipements :

Chiller                                                 : ok, temperature converged quickly to the set temperature : 25°C
Cavity mirrors motors controller         : I had to configure the general network as 192.168.xxx.xxx in order to operate the software designed by Didier Jehanno
Computer                                           : ok, now, it IP address is 192.168.1.1
Laser amplifier controller                    : I had a LOT of issues in restarting the LAL software. I had to restart several times the amplifier controller in order to access it by software. I quickly check the power increase to 50% after it has been correctly seeded
CW oscillator                                     : ok, Koheras restarted without any issue.
OneFive oscillator                             : the power ON was ok but it did not modelock. I tried several gently knocks on the case but without success (one clearly see the effect on the scope, the oscillator "tries" to modelock).
                                                            fortunately, after about 1h, the oscillator modelocked alone (check with Buddy fiber photodiode + scope).... the power is the same as before. the Alphanov software measures 5.4mW (it was 5.5 mW the 2/1/2023)

Smaract controller for OneFive        : ok, I changed its IP address to 192.168.1.10. I tested the PC control in moving forth and back the "CEP" motor by 1mm... the OneFive was still modelocked.
 

Today, we restarted the FP-cavity locking, after 3 weeks without using it.
those 3 weeks have been used to set the machine ring at the new (better) frequency : 500.067MHz (corresponding to a change of -183kHz)
or 33.3378MHz in fondamental frequency (corresponding to a change of -12.2kHz)

the power supply of FP-cavity photodiodes was OFF maybe due to some electrons losses.
we had to switch it OFF and ON to restart it.

the computer was restarted and we had to restart the applications and set their parameters.
in attachement, the parameters of the Kangoo software.
we had several "warnings" from the laser amplifier software => the amplifier stopped
but maybe it's because of the electrons not sent in the dump which pertubate the monitoring signal levels of the amplifier => to be confirmed

we had to do some alignment.
with 33% of  amplifier ratio, we had 49kW inside the FP-cavity.
we tried to move a bit the L-shape mirror but without any significant effect to improve the intra-cavity power.

we didn't start the laser and FP cavities length increase procedure.

surprinsingly, the beating frequency between laser cavity and 33.3378MHz is only 140Hz and not 12kHz as expected.... to be investigated
 

this morning I solved the problem of the 33MHz frequency beating which should be ~12kHz between the generator (at the new frequency 33.3378MHz) and the laser cavity frequency (still at the old frequency which is 33.35MHz)...
the generator providing the 33MHz frequency has 2 channels, and only one was set at the proper frequency !

so, I set both channels at  33.3378MHz and now I measure properly ~12kHz of frequency beating.

now, we can move the laser cavity and the FP cavity in confidence.

this morning, I finished the FP-cavity alignment with the new ring RF frequency.
I get back 50kW @ 33% amplifier ratio.

I'm also able to lock very smoothly on the 500MHz ring RF frequency.
so, we are ready to produce X-ray.

warning : apparently, when one changes the 33MHz generator frequency with the "Nicolas" script, it does not change both channels of the generator, which is mandatory for us.
=> to be fixed : freq(CH2) = freq(CH1)

new optimized lock parameters in attached file (Kangoo parameters)

no more "Alphanov amplifier warnings" when one works without the ring machine => it is important/mandatory to send the electrons in the dump.

 

the previous password has expired.

the new access from the computer :
login : .\$jehanno
pwd : ThomX23456

the new access in remote:
login : $jehanno
pwd : ThomX23456

today, we had a strange effect :
both the laser and the FP cavity were locked on the RF frequency (500.10045 MHz), and we were producing X-rays but with a slowing (several seconds) fluctuation exactly as the electrons-photons phase was drifting and the fluctuation can goes to 0 Xrays produced even at the "right" phase.
but the ring people says there is no phase fluctuation in their measurements.
and I looked the baseline of the 500MHz beating (which is the synchronisation signal with electrons) and I didn't see any fluctuation either.

we tried 2 other ring frequencies : 500.10030 MHz and 500.1 MHz.
there were still X-rays production fluctuations but with a faster rate.
when we went back to 500.10045 MHz, we found back the same X-rays production fluctions at a slow rate.

to remove this effect, I had to add an integrator gain (I = 1e-6) in the Laselock in the FPC/RF loop.
this integrator was not used (I = 0) in the previous stable X-rays productions....

it means that we have now a slow phase fluctuation.
we have to check if we see these fluctuations in the 500MHz beating signal.
loosing the Xrays means we moved by the packet length dt ~ 50ps which is equivalent to 9° @ 500MHz of fluctuation.
with A= +/-1V signal, it would be equivalent to a drift of ~ A*(2pi*dt/T) ~ 157mV !!!
it is strange we didn't see it => to be checked !!!

conclusion : now, we have to put this I=1e-6 in the FPC/RF loop to get a stable Xray production.
but the locking acquisition works better with I=0.
so we need to remove it before starting to lock and then, when the lock is stable (but the X rays are poor), we need to put I=1e-6 => the Xray flux inscreases dramatically.

The cavity has been cleaned then put under primary vacuum (primary pump without vacuum flow control). Dusts presence was checked at air and no significant changes have been observed.

1ST image before cleaning
2ND image after cleaning
No changes after coming back from primary vacuum

from now on, one reverts the FP cavity motors direction to compensate the long drift from the begining of the project.
the motor MOT.06 will be used for the upward direction (presently -1 082 650 steps)
and the motor MOT.03 will be used for the downward direction (presently +37 170 steps)

after CEP and walking alignment tuning, I got quickly 92kW.

the new MOT.06 and MOT.03 positions are : -1 071670 steps and +34 110 steps.
the CEP motor is at +345µm

to anticipate the power shut down on next tuesday 23/09,
this afternoon, I switched off all the equipments except the oscillator connected on the UPS.

this morning, I restarted all the equipments of the FPC.

everything was fine after being able to get back the correct PDH phase between modulation and demodulation...I got 88kW with 33% amplifier ratio after basic alignment and CEP tuning.

the Pico1 server used for the X-ray photodiode TMD.01 doesn't want to start...
I tried with Astor. the server start to run (red => blue => green colors)
but when I start the Jive panel, it gets down again (red color)... to be solved

the 33MHz/500MHz RF frequencies from the Ring seems different from the previous state (maybe working at an energy of 50MeV instead of 70MeV which was the previous energy ?).

so, I let the FPC at the present position and wait to discuss if it is necessary or not to move the FPC motors for the correct energy...

This morning I did a phase alignment on the PDH signal generator (Rigol DG4102)
this procedure ensure that both phases of the sine wave signals are aligned before finding the correct phase for maximizing the error signal.

so, from now on, in case of power shut down, one just need to :

1) do a phase alignment

2) put the correct phase number on the 2 channels according to the picture (if not automatically done by the generator itself).

340° on channel 1
270° on channel 2

1) and 2) can be done in any order.