long run to test the appearance of high frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics 
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Today with Daniele, we did 6 long runs at different power (23kW, 46kW, 66kW, 73kW, 92kW, 92kW)
All the lock loss in between these several runs are due to FPC locking parameters change.
most of the few lock losses during the stable power duration, are due to 20Hz oscillation noise or because we forgot to center properly the PZT |
long run to test the appearance of high frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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today, long run directly at full power (33% amplifier ratio) => 98kW in the FPC at the very begining of the run.
(P=0.05 / I=0.0005 / D=0.6)
10-40 min : almost misalignment effect (CEP did not change so much) |
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laser PZT amplifier, posted by Ronic Chiche at ThomX igloo about detectors and electronics
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this afternoon, I added the Gain = 2.8 amplifier at the output of the Laselock to drive the laser PZT.
the power supply of the board is disymetric to address the correct maximal dynamic range of the amplifier (~ 30V) and voltage drop (~ 2V) related
to the power supply voltage. |
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New recipies with additionnal attenuation before the diffuser and new x3 amplifier on laser PZT, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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With optical attenuation + x3 amplifier on laser PZT channel + feedback tuning
Temporary recipie for ~ 92kW power in the FP-cavity:
(in the previous scheme, without x3 laser PZT amp, a good lock was achieved for a PDH signal power noise ~ 70 mV rms) |
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Tuning of the slow feeback loop analog BW + fast feedback loop gain + PID, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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Today with Daniele, we tuned the potentiometer after the Laselock which drives the analog BW of the PID on the laser PZT,
and we tuned also the fast loop gain (with the rotary potentiometer dedicated to it) => the PID parameters have changed.
so, the recipies has changed => to be updated |
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Stability test Without and with , posted by Ronic Chiche at ThomX igloo about lasers and optics
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The laser starts at 93 KW.
This morning I operated the laser locked with the RF for 1h30 without any delock. All the machine was switch off.
All the system was very stable. Sometimes the 20 Hz perturbation was visible but no delocking. |
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Suite tests stabilité, posted by Ronic Chiche at ThomX igloo about lasers and optics
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We continue to find what gives high freq. perturbation.
The laser starts at 92 KW it is stable and locked to the RF. NO high freq parturbation.... With the machine off. (30 min of lock)
We put now the machine ON (All in warming exept pulsed elements)... => the system is very stable NO delock, NO high freq perturbations. The |
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Xrays experiment with prostate, posted by Ronic Chiche at ThomX igloo about lasers and optics
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Today we do XRays for experiment.
The laser start to 33% at 93 KW but Pgain = 0.033
The laser is locked so stable for the moment. We have Xrays and the system is stable. |
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laser operation again with machine OFF, posted by Ronic Chiche at ThomX igloo about lasers and optics
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The laser start at 33% with 92 KW optimized and
P=0.03
I=0.0005 |
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Alignment correction during the summer break, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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I restarted the FPC system this morning.
after some classic alignement procedure (some LEFT steps on the cavity injection motors X & Y) and CEP tuning,
I got 92kW for 33% amplifier ratio. |
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Power shut down on August 29th, posted by Ronic Chiche at ThomX igloo about detectors and electronics
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This morning, all the equipments have been switched off due to a power shut down tomorrow morning.
Only the Onefive oscillator is still ON, connected to the Uninterruptable Power Supply (UPS). |
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Power shut down on August 29th, posted by Ronic Chiche at ThomX igloo about detectors and electronics
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after alignment, CEP adjustment and optimizing the PDH phase, I got back ~92kW in the FPC for 33% amplifier ratio.
Ronic
Chiche wrote:
This morning, all the equipments have been switched off due to |
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polarization measurement of the FP cavity beam, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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today, with Daniele, we did a simple polarization measurement in transmission of the FP cavity beam.
1) we locked the FP cavity and measured 82.5kw (for 33% amplifier ratio) with the power-meter moved a little bit further (this is maybe the reason
why the power is a little bit lower than usually measured). |
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Accelerometer measurement, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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with Daniele, we placed the accelerometer on top of the fiber amplifier box which is inside the housing.
the goal was to try to detect a correlation with some possible accoustic noise coming from the bubbles of the water, cooling the amplifier box baseplate.
we monitored a long trend of the transmission which is perturbated when high frequency noise arises, and the accelerometer signal. |
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Power shut down on September 23th, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics | cabling | software | utilities
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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. |
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Power shut down on September 23th, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics | cabling | software | utilities
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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. |
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Power shut down on September 23th, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics | cabling | software | utilities
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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... |
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Power shut down on September 23th, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics | cabling | software | utilities
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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 : |
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High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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Today, the lock of the FPC was particularly bad (maybe the worst ever seen), with a lot of high frequency noise.
the lock was impossible during several minutes !
we tried to switch off all the equipments of the machine, one by one without any effect on the lock. |
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High frequency noise, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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At the end of the day, we found out what was the origin of this noise : some road renovation work with jackhammer and road roller just at the entrance
of the "Igloo".
this origin was 100% correlated with a large increase of the accelerometer signal. |