Re: RF Conductivity of thin Mo film

Peter Simon wrote:
> 
> "Uncle Al" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
> > Peter Simon wrote:
> > >
> > > I am very interested in predicting the RF reflection and transmission
> > > (at a frequency of 2.6 GHz) through a thin layer of Molybdenum (Mo)
> > > that may be sputtered onto a 2 mil plastic substrate.
>  [snip]
> >
> > Are you interested in the amount of Mo deposited and then RF
> > properties, or something else?  Why not have a naked quartz oscillator
> > crystal in there and track the change of resonant frequency with
> > increasing mass?  It's a commercial system.  Do your RF measurements
> > concurrently, already knowing the film thickness to excellent accuracy
> >
> [snip]
> > The only no-no is that quartz undergoes a solid state twinning
> > transition at 573 C.  Don't go above 500 C at the crystal.
> >
> > --
> > Uncle Al
> 
> I don't wish to measure the amount of Mo deposited.  I am attempting to
> predict the amount of RF performance degradation to expect over the life of
> a spacecraft mission due to undesired Mo sputtering.  My calculations will
> help to determine the maximum tolerable Mo layer thickness, and will be used
> as inputs into the decision as to what, if anything, needs to be done about
> the undesired sputtering.

   0) Looks to Uncle Al like you want to measure the amount of Mo
deposited/time, either way.
   1) If it is low earth orbit, will you get erosion as volatile MoO3
or (non-volatile) Mo suboxides from local energetic oxygen atoms?
   2) An Mo surface rubbed with diamond dust rapidly forms an Mo
carbide layer (distinct color change).  Is that protective?
   3) Will an Mo surface rubbed with silicon dust form a protective Mo
silicide layer?  That oxidizes to an adherent layer of amorphous
silica. 
   4) If you implant both C and Si...

An engineer's first goal is to determine the real problem.  After
that, one pursues real solutions.  Given NASA's proven inablilty to
properly unfurl an antenna (Ulyssess and Hubble), a little window
fouling would demand a low tech solution.  NASA is institutionally
incapable of handling high tech.

-- 
Uncle Al
http://www.mazepath.com/uncleal/
 (Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?"  The Net!