[Fwd: Re: [Fwd: Collimator layout questions...]]

[Tim Whitlatch <whitey@jlab.org>]

-------- Original Message --------

Subject:	Re: [Fwd: Collimator layout questions...]
Date:	Mon, 07 Jul 2008 16:59:11 -0400
From:	Tim Whitlatch <whitey@jlab.org>
To:	Richard Jones <richard.t.jones@uconn.edu>
References:	<486C0B7C.8050407@phys.uconn.edu> 486D86A6.4020808@uconn.edu"><486D86A6.4020808@uconn.edu> 48722661.8020207@jlab.org"><48722661.8020207@jlab.org> 48723B50.5070304@uconn.edu"><48723B50.5070304@uconn.edu> 4872516B.1@jlab.org"><4872516B.1@jlab.org> <48726025.7030207@uconn.edu>

Hi Richard,

I believe you are correct. There is no limit for deflection. I was 
mainly concerned about yielding the kapton. But after some more thought, 
once the material has yielded to form a spherical shape, the stresses 
reduce.It should be fine.

Tim

Richard Jones wrote:
> Tim,
>
> I don't know of any upper limit on the deflection allowed for this 
> window.  Isn't a half inch a very small deflection for such a window?  
> I would expect a deflection of something like 1/5 - 1/4 the radius for 
> an optimally thin window.  What am I missing here?
>
> Richard Jones
>
> Tim Whitlatch wrote:
>> Hi Richard,
>>
>> A quick calculation of a .5mm Kapton window with a 20cm diameter will 
>> exceed the yield strength of the material and deflect over .5 inches 
>> at the center under full vacuum. In order to stay under yield stress, 
>> it will need to be greater than 1mm thick.
>>
>> Tim
>>
>

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