day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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today, after 1 week of vacation, I was able to easily lock the cavity with 92kW with 33% amp ratio without too much optimizations (no walking alignment).
could it be related to the nice weather we got during this week ?
as in the past we observed more noise when the weather was changing and we had very difficult locking procedure after a simple weekend... |
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day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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Today, I removed the NKT oscillator from the bunker to put it in the PLIC room.
I locked the FP cavity and obtained 97kW with 33% amplifier ratio, without any alignment, just by changing a little bit the CEP.
Ronic |
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day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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New locking parameters (I got 98kW for 33% amp ratio) :
Axis 18 position : +0009420
P = 0.05 |
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day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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We had a long run without any lock loss during ~1h with the 23kW recipie in the morning.
during the afternoon, we had some few lock losses but the FPC system was globally quiet and stable,
but at the end of the day, I observed more and more frequent high frequency noise which implies lock losses. |
day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 
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long run yesterday at relatively low power (~23kW) with double loop (FPC + RF) between 10am and 6pm
Ronic
Chiche wrote:
We had a long run without any lock loss during ~1h with the 23kW recipie |
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day by day run for X-ray production, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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long run today at relatively nominal power (~90kW) with double loop (FPC + RF) between 13:30am and 6:30pm
Ronic
Chiche wrote:
long run yesterday at relatively low power (~23kW) with double loop |
correlations between vacuum gauges and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum
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the machine people saw a correlation between BPM jumps and vacuum gauges peaks related to breakdowns in the beam pipe.
these breakdowns could produce some accoustic noise which could be related to our lock losses.
=> we tried to do a corrrelation between our lock losses and the vacuum gauge peaks => WE DON'T SEE any correlation !!! |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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I installed an accelerometer setup in the bunker.
presently, the accelerometer is placed on top of the housing and its signal is connected to the 2nd scope (33MHz and 500MHz RF beating) on channel
4. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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today I connected a copy of the laser PZT signal to the 2nd scope CH2 (with AC coupling to remove the DC offset) to be able to monitor synchronously
the Accelerometer and laser PZT signals.
the accelerometer is still connected to the 2nd scope CH4 and placed on top of the housing. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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this morning, I did some measurement with nobody interfering with the tests.
- the "no noise" image shows a standard situation during 10s when there is no noise either on PZT or Accelerometer.
most of the time, we are in this situation. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 8x
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then, I moved the accelerometer on top of the "X-hutch side" vessel, placed directly on the metal top case, inside the housing.
- the "no noise same range" image shows a standard situation during 10s when there no noise either on PZT or Accelerometer.
on can compare the noise level on the accelerometer with the previous post when it was outside on top of the housing. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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at the end of the day, I moved the accelerometer from the top of the cavity vessel to the top case of the Onefive laser.
I quickly saw again quite strong correlations between the vibrations compensated by the PZT and the accelerometer signal.
when one does a laser motor step which makes a systematic lock loss, one doesn't see any signal on the accelerometer. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 6x
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this morning, I did some new plots with the accelerometer placed on the top of the case of the OneFive laser.
I previously observed with the accelerometer placed on the top of one cavity vessel, the correlation between the accelerometer signal and the PZT
noise is pretty good but not 100%. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 7x
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new plots, with the accelerometer placed directly on the optical cavity table (on the marble part), close to the oscillator.
the correlation seems a bit better....
we would need to put the accelerometer on one foot of the table to check if the table has not some micro-movement or at the IP to check if the |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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one possible source for this acoustic noise was the vibrations coming from the water cooling of the dipoles which is normally never turned off even when
the machine is off.
this afternoon, Kevin turned off the main valve of the water cooling of half of the dipoles (the half on the FPC side), and we recorded the peak-peak |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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here is the pk-pk measurement of the accelerometer during the whole night.
the recording started at 5pm yesterday and has been stopped this morning at 10am.
one got 28k points in 17 hours => 1.65k points / h |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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here is the acquisition from 10:30am to 5:30pm
11k point in 7h => 1.57k points / h
the noise is almost the same during the daylight, a little bit increasing from 1:30pm. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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here is the same kind of measurement (pk-pk of 1 sec of acquisition) done on the laser PZT when the FP is at 90kW.
it's from 6:20pm to 7:10pm => ~2.4s by point
the minimum values are for the PZT being off. |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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long term pk-pk measurement of the accelerometer (placed on the optical cavity table, on the marble part close to the laser oscillator) from 5:30pm to
9am => ~ 2.255s / pt
start of the quiet period : ~ 5k pts <=> 8:45pm |
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correlations between accelerometer and lock losses @ 20Hz, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics
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I installed the accelerometer on the ground close to one feet of the FP cavity hexapod (see picture) and restarted the acquisition at 6:40pm on 20th
of february.
the acquisition corresponds to the night between the 20th and the 21th of february. |