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I need to fix a leak on the inside of a liquid nitrogen dewar which acts as the coolant tank for a spectroscopy CCD camera. Due to the design of the camera, I unfortunately can only access the inside of the dewar via its bottleneck. Since the dewar is permanently connected to the camera body, the only idea I could come up with is spraying the inside with a material that hardens afterward, hoping to hit the leak in the process and therefore sealing it while also not depositing too much material. I roughly sketched the idea. Rough sketch of camera interior and spraying idea

Let's suppose the dewar is made out of aluminum. Which material would be suitable to be sprayed onto the inside, adhering well to the aluminum after hardening and can be expected to withstand rapid temperature changes and low temperatures (-200 °C) over long periods of time?

Side note: I know this idea is sketchy, but we need to get this camera back running as soon as possible and are already working on replacing it in the near future.

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  • $\begingroup$ Can you place the broken Dewar inside a larger Dewar? $\endgroup$
    – RC_23
    Commented Aug 25, 2023 at 20:33
  • $\begingroup$ @RC_23 Due to the construction of the camera this is unfortunately not possible $\endgroup$
    – Mika R.
    Commented Aug 26, 2023 at 18:09
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    $\begingroup$ Unless I've misunderstood, the gap between the inner and outer walls of the Dewar is now full of gas, not full of vacuum, so even if you seal the leak perfectly, the flask won't operate as a Dewar flask any more. $\endgroup$
    – user28774
    Commented May 23 at 9:57

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So, either increase the pressure in the flask and atomise the sealing fluid so it gets into the hole,

OR:

Put the dewar in a chamber with the neck outside then lower the pressure and achieve the same.

Much like the tire slime put inside tires to seal punctures.

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