New direction for cavity motors, posted by Ronic Chiche at ThomX igloo about mechanics | software
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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) |
Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics 
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we installed a measurement at the IP with the BPM for ion cleaning for electrons and we used a fast photodiode at the output of the FP-cavity and measured
with a fast oscilloscope the phase jitter between the 2 signals.
in red, the BPM signal |
Electrons-Photons phase stability measurement, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics
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the phase between the 500Mhz ring RF oscillator and the electrons is measured on a BPM and is very stable after 2-3ms (<< 6ps, typically) !
in the same time, we can use the residual phase beating after our 500MHz mixer to estimate the phase noise coming from the laser part.
the rms noise of this signal is around 60mV for 1.25V peak (2.5 pk-pk) signal => ~ 50mrad rms |
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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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this morning, the cavity was pretty misaligned => basic alignment in y direction helps a lot => 93kW for 33% amp ratio.
the Rigol 33MHz generator phase was adjusted : phase ch2 = phase ch1 (40 deg) + 36 deg = 76 deg.
Ronic |
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New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics
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today, we were able to store more than 95kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio
Ronic
Chiche wrote:
today, we were able to store more than 94kW in |
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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, the alignment of FP cavity was so bad that I tuned the 01 mode by error (CEP and alignment)... insead of the 00 mode !!!
I was able to reach ~30kW and was limited at this value, so I used the camera to check what was happening and saw the 01 mode.
so, I moved the lock on a 00 mode and redid a full tuning (CEP and alignment). |
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New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics
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today, we were able to store more than 97kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio
Ronic
Chiche wrote:
today, we were able to store more than 95kW in the FP cavity, always |
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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, 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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air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics
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The temperature slitly increase in thomx Bunker from 23° to 24° during the last day.
The thermalisation of the CFP is very long...
In any case the operation of the CFP is so easy, it seems to be correlated to the weather... tody it's very nice as of hte rest of the week. |
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air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics
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after the new temperature setting for the bunker air cooling (winter to summer transition), the temperature drop from 24° to 20°C which induced
a slight misalignment between the onefive oscillator and the fiber injection.
the amplifier photodiode PD_IN which checks the amplifier power injection drop also from 3mW to 2.885mW... hopefully, it is enough to start the |
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air conditionning in ThomX Bunker, posted by Ronic Chiche at ThomX igloo about lasers and optics
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I finally got 93-94kW for 33% amp ratio.
I had to move the FP-cavity length to compensate the temperature change in the bunker.
doing that, I had the message "Low Limit SW pressed" when I tried to move P4z under -98 000 steps !!! |
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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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33MHz phase adjustment, posted by Ronic Chiche at ThomX igloo about lasers and optics | detectors and electronics | software
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the 33MHz beating signal (phase) is used to start and stop automatically the lock on the 500MHz beating signal.
this 33MHz beating phase has a fixed range (typically +/-0.5V), so it is important to center this beating phase in the middle of its own range
when the 500MHz signal is locked |
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Possible causes for the noise in the FP-cavity system, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics
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list of possible causes of the high frequency noise which makes the system loosing the lock => to be checked.
(if you have some new idea, I will edit the post)
1- Laser |
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New power record in ThomX cavity, posted by Ronic Chiche at ThomX igloo about lasers and optics
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yesterday, we were able to store more than 98kW in the FP cavity, always with the same parameter : 33% laser amplifier ratio
Ronic
Chiche wrote:
today, we were able to store more than 97kW in |
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Possible causes for the noise in the FP-cavity system, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | vacuum | detectors and electronics
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4.3 - Vibrations of the mirror mounts due to temperature related to cavity power (the electrons machine is OFF)
1) to test this possible issue, we plan to make a run at low power in the FP-cavity, around 10kW, instead of ~90kW as usual.
for that, I will need to change the diffuser position on axis 18 to get the same error signal for the locking. |
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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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Recipies for different FPC power, posted by Ronic Chiche at ThomX igloo about lasers and optics
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For ~ 46kW power in the FP-cavity:
Alplhanov amplifier ratio : 20%
Axis 18 position : -0004710 steps |
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Recipies for different FPC power, posted by Ronic Chiche at ThomX igloo about lasers and optics
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For ~ 23kW power in the FP-cavity:
Alplhanov amplifier ratio : 15%
Axis 18 position : -0016014 steps |
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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. |