Re: Superconducting tesla coil...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

the GP45 LN2 is $100 for a fill (as of a couple years ago, Gilmore, in Los
Angeles).. Purchase price is around $2-3K, as I recall.. If you drop one and
break the vacuum seal, that's what they stick you for, anyway. $30/mo is
about what I recall for demurrage (rent), but you had to pay for the gas on
top of that... It was about 1/2 the cost of buying nitrogen in 3000 psi
bottles, and you get nice dry nitrogen.
About 1% -2% loss per day..
These days, at work, we just have the truck back up to the bulk tanks all
over the lab...

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, October 03, 2003 8:35 PM
Subject: RE: Superconducting tesla coil...


 > Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com>
 >
 > I looked into LN2 for a CryoPump some time ago, and the 45 gal Dewars
 > can easily be rented for $30/month (that includes the LN2!).
 > Unfortunately I have never run across one of those dewars for only $100.
 > Jim, what's your source?
 >
 > Regards,
 >
 > David Trimmell
 >
 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Thursday, October 02, 2003 6:47 PM
 > To: tesla-at-pupman-dot-com
 > Subject: Re: Superconducting tesla coil...
 >
 > Original poster: Jim Lux <jimlux-at-earthlink-dot-net>
 >
 > Having done experiments along these lines, for those contemplating using
 >
 > LN2 and immersing a TC....
 >
 > At 05:55 PM 10/2/2003 -0600, you wrote:
 >  >Original poster: The MCP <ejkeever-at-comcast-dot-net>
 >  >Heck, liquid nitrogen isn't *that* expensive, is it?
 >
 > LN2 == Milk as far as cost goes... $.50/liter... $100 gets you a big
 > GP45
 > dewar (that's 45 gallons, folks)
 >
 >
 >
 >
 >  >  But I'd want to be
 >  >careful that my components have similar thermal expansions. Use
 > something
 >  >with a large theremal expansion coefficient as your winding on
 > something that
 >  >doesn't, and you'll get broken/stretched wire as the wire shortens and
 > tenses
 >  >up.
 >
 > Precisely the problem you'll have... particularly things that are
 > plastic,
 > aren't when cooled to 77K...
 >
 >
 >  >Other than that, you'll have to construct a vessel around the coil to
 > contain
 >  >the LN2.
 >
 > Styrofoam is your friend... Those inexpensive plastic water coolers from
 >
 > Home Depot work quite well to hold LN2.  However, seal up the hole where
 >
 > the spout is at the bottom before filling.. if it starts to leak, you'll
 >
 > never be able to patch it.  Putty or epoxy works fine.
 >
 > I'd try using something like sonotube in a larger sonotube (or 5 gal
 > plastic buckets) with the space between filled with "foam in a can" or
 > expanded vermiculite/perlite
 >
 >
 >
 >  >Reminds of an interesting reference from Ben Bova's Moonwar. They refer
 > to the
 >  >mass driver as using "cryogenic aluminum" magnets rather than
 >  >supercondcucting magnets. When was the book written; The first
 > high-temp
 >  >superconductor was created in the early 80's, right?
 >
 >
 > High power magnets have used LN2 cooling for many years.
 >
 >