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Entry   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 
    Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 
       Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 
          Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics Screenshot_2023-11-30_15-48-05.png
             Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics 2023_12_01_temp_freq.png
                Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics untitled.png
                   Reply   Temperature control of the FP-cavity length, posted by Ronic Chiche at ThomX igloo about mechanics | lasers and optics | detectors and electronics frequency_drift.png
Message ID: 297     Entry time: Wed Nov 29 12:20:18 2023     In reply to: 294     Reply to this: 301
 Author: Ronic Chiche 
 Status: Fixed 
 Type: issue 
 Category: mechanics | lasers and optics | detectors and electronics 
 Location: ThomX igloo 
 Title: Temperature control of the FP-cavity length 

today, I removed one of the DC voltage supply (as with 30V, we are already able to 30°C on the heating cable).

the remaining DC voltage supply is configured in series (2x30V = 60V max) and is at the IP address : 192.168.1.101

Ronic Chiche wrote:

several days ago, we installed a heating cable around the output flange (close to the X-hutch) of the FP-cavity vessel.
we are able to heat this cable by applying a DC voltage coming from 2 DC voltage supplies in serie (2 devices with 2x 0-30V / 3A => 0-120V / 3A).
currently, we apply at maximum 7V DC on each channel => 28V DC on the cable. its temperature reach ~ 30°C after 1/2h or more.

this temperature increase on one vessel of the FP-cavity, changes very slowly the length of the FP-cavity.
see this post (red curve on fig. 2) for a typical temperature curve measured (exponential-like curve) on the heating cable itself : https://elog.lal.in2p3.fr/FPC/THOMX+commissioning/290

the length change rate of the FP-cavity, due to this heating, is difficult to estimate because it depends on the part of this exponential curve you make the measurement.
but globally the drift is about 50nm every 5 minutes, which is roughly equivalent to 10 steps of the FP-cavity motor every 5 minutes.

Ronic Chiche wrote:

as the CFP motors displacements induce a cavity unlock, we try to change the cavity length by changing the temperature of elment of the cavity.

yesterday, we tried to put a "heating cable" borrowed to the vacuum group to change the temperature of one bellows between the FP-cavity and the electron ring.
we chose a below because it is flexible and should not apply a too strong force on the cavity vessels.
we heated the cable at ~30°C but we didn't see a clear effect on the FP-cavity frequency measurement.

then, we put a heating cable around the X-ray output flange of the FP-cavity vessel and we saw a clear effect : a relatively fast (at a "second" level) frequency change.
the problem is the heating system is not remotely driven.

the cable is R=55ohms impedance and can reach 450°C for 1kW dissipated.
so today, we will try to use 2 remotely controlled Siglent SPD3303X power supplies.
they can reach V=120V DC => P=V²/R=260W => we could reach more than 100°C

 

 

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