[time-nuts] CRYO Voltage standards

Robert Atkinson robert8rpi at yahoo.co.uk
Mon Dec 1 16:31:46 EST 2008

I've played with cryogenically coolled Thermal imagers (yes as a hobby, but work too). and LN2 has a lot going for it. It's cheap and does not wear out (as stirling cycle and peltier coolers do) and is safer than high pressure pure air. That reminds me I've a source for some 24V pure air compressors that were used for TOW sights ;-) 
Robert G8RPI.    

--- On Mon, 1/12/08, Lux, James P <james.p.lux at jpl.nasa.gov> wrote:

From: Lux, James P <james.p.lux at jpl.nasa.gov>
Subject: Re: [time-nuts] Voltage standards
To: "M. Warner Losh" <imp at bsdimp.com>, "time-nuts at febo.com" <time-nuts at febo.com>
Date: Monday, 1 December, 2008, 12:45 AM

On 11/30/08 4:27 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:

> The thing that got me was the word 'really' in Bruce's
statement.  It
> read like someone who had tried it, had limited success, but in the
> end wound up believing that while possible, it wasn't really
> practical.  After thinking that, I couldn't imagine that somebody on
> the list hadn't tried it for some reason or another over the years.
> After all, as you say, a fine bottle of scotch isn't that expensive
> when it comes to the pursuit of your obsessions :)
> Warner

And surely, with these grim economic times, liquid helium dewars are going
to be popping up on the surplus market. Then, at least, you'll have a place
to store that liquid helium.

And speaking of cryogens, has anyone on the list done cryogenic sapphire
ring oscillators? (at home)  After all, folks at JPL are doing this
" We present design progress and subsystem test results for a new
frequency standard, the Voltage Controlled Sapphire Oscillator (VCSO).
Included are sapphire resonator and coupling design, cryocooler
environmental sensitivity tests, Q measurement results, and turnover
temperature results. A previous report presented history of the design
related to resonator frequency and frequency compensation [1]. Performance
goals are a frequency stability of 1×10-14 (1 second ≦ τ ≦100 seconds)
two years or more continuous operation. Long-term operation and small size
are facilitated by use of a small Stirling cryo-cooler (160W wall power)
with an expected 5 year life." http://hdl.handle.net/2014/39769

Seems that running a cryocooler is probably a bit easier than pouring liters
of liquid helium into a cryostat.


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