[time-nuts] homebrew H maser

[jimlux]

Poul-Henning Kamp wrote:
> In message <4C7F5918.7030101 at xtra.co.nz>, Bruce Griffiths writes:
> 
>> Indicates that the operating pressure at the hydrogen dissociator is 
>> likely to be a few Torr or so.
> 
> The pressure is basically: "As low as possible" in order to minimize
> hydrogen collisions (other hydrogen, walls) as much as possible.
> 


A few torr is actually not a particularly high vacuum (e.g. your run of 
the mill neon sign is pumped down a lot lower before being filled to a 
few torr).

PHKs comment implies you're looking for mean free path somewhat greater 
than physical dimensions...
That would imply pressures less than a micron (0.001 Torr)..  MFP = 
5E-3/P with P in Torr.. 1 micron pressure == 5cm MFP

The other thing is when you're looking at MFP comparable to dimensions, 
you're looking at molecular pumping in some form (no more pistons or 
rotary vanes or ...)