[time-nuts] Re: hydrogen rich environment and oscillators

[Lux, Jim]

On 12/12/22 2:43 PM, Alex Pummer via time-nuts wrote:
> Look for Knutdsen effect:
> Knudsen diffusion, or Knudsen flux, *occurs when the mean pore 
> diameter of the porous medium is smaller than the mean free path of 
> the gas particles*. This type of diffusion occurs in low permeability 
> porous media, which have small pore radii, and at low gas pressures, 
> when the mean free path becomes large.
> 73
> KJ6UHN


This would be at atmospheric pressure, so MFP is on the order of 60 nm.  
I suspect that the pores in metal or silica or whatever are much smaller 
than that.



> On 12/12/2022 2:09 PM, Lux, Jim via time-nuts wrote:
>> On 12/12/22 11:21 AM, Zen via time-nuts wrote:
>>> This is true and was proven by experimentation. But I believe it was a
>>> Helium atmosphere not Hydrogen. The He poisoned the MEMS oscillator 
>>> in both
>>> phones and watches. Fault time was about 30 minutes recovery time 
>>> was about
>>> 3 days. Concentrations were small enough that and employee filling 
>>> party
>>> balloons at a store had a dead I phone for a while.
>>
>> Yes, but H2, while a bit bigger than He, is still pretty diffusable 
>> (if that's the right word).
>>
>> And, I believe the iPhone event was a very tiny MEMS resonator in a 
>> vacuum.
>>
>> I've been poking through the literature and reports, but it does not 
>> appear to be a "well studied problem".
>>
>>
>> The challenge is that with Cubesats and the like making more use of 
>> COTS components and techniques, there's not a lot of history to go 
>> back to.  Space qualified parts get leak tested with He, etc. so 
>> their hermeticity is generally good.  The same is not necessarily 
>> true of other devices.
>>
>>
>>
>>
>>
>>>
>>> Eric
>>>
>>> -----Original Message-----
>>> From: Poul-Henning Kamp via time-nuts <time-nuts at lists.febo.com>
>>> Sent: Monday, December 12, 2022 10:10 AM
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at lists.febo.com>
>>> Cc: Poul-Henning Kamp <phk at phk.freebsd.dk>
>>> Subject: [time-nuts] Re: hydrogen rich environment and oscillators
>>>
>>> --------
>>> Lux, Jim via time-nuts writes:
>>>
>>>> Does anyone have any information on what happens to hermetic TCXOs
>>>> when they're in a hydrogen rich atmosphere?
>>> What kind of hydrogen concentration are we talking about ?
>>>
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