Re: Stimulated Raman Scattering in N2 gas

"Detector195" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> [EMAIL PROTECTED] (Mily) wrote in message
news:<[EMAIL PROTECTED]>...
> > Hi,
> >    I'm interested in generating 1414 nm (the 1st Stokes)in N2 gas by
> > pumping it with 1064 nm of Nd:YAG laser. The one which we have in our
> > lab has a peak power of 950 mJ/P (model is Quanta Ray PRO 170). I
> > would like to know the following things about SRS in N2 gas :
> > 1. Is there any plot of pressure of N2 gas Vs efficiency of SRS
> > available?
> > 2. How one can reduce the Stimulated Brillouin scattering in N2?
> > 3. What effective path length of Raman cell will be useful?
> > 4. We want to use stainless steel for the fabrication of Raman cell.
> > What
> >    thickness of steel will be appropriate to hold the gas at high
> > pressure,
> >    say 50 atm?
> > 5. Instead of putting the flanges with too many nut and bolts, is
> > there any
> >    other way to get rid of leakage? Can we do with minimun no. of nut
> > and
> >    bolts?
> >
> > Look forward to your response.
> > Sincerely yours,
> > Mily.
>
> Maybe this just shows my ignorance of Raman, but could you use liquid
> nitrogen? If not, perhaps you would do me a favor and explain why,
> since I am curious about this.

You can use liquid N2, its been done, but is experimentally a *pain*; you
need double windows & turbulence & bubbles wreck the beam. Remember the
Raman effect does deposit power in the material; that makes LN2 boil &
convect............. Also its hard to keep the LN2 clear of tiny ice
crystalss etc, needs top be very pure, & colled below boiling (by pumping on
it for a bit & then returning to one atmosphere) to *stop* it boilking.
Done years ago & dropped. A

I agree that you should only design yourself if you know what you are doing!
It needs proper stress calculations etc, & seeking to minimise the number of
bolts as a prime objective is a good way to get hurt! Incidentally so called
'over bolting', ie tightening the bolts too much so they are under severe
tensile stress *before* the vessel is pressurised, is a good way to make
bolts fail. They should *always* be tightened with a torque wrench.
That said, unless there is gross miss design, failure of the metalwork is
not that likely.
But window falure is, & can eject shrapnel. The window is a brittle material
& the standard design methods are not really valid, 'safety factors' very
dubious; a sfratch in tension can cause even thick windows to fail, so can
edge chips, so can poor mounting with stress raisers.

Furthermore your vessel may well be subject to legal requirements on its
design, testing & certification, & may require specific inclusion on
insurance documents. If not, & anything happens, you are in DEEP trouble!

As you may gather, a good many years ago I designed one. But i think there
is a commercial source.

Harvey