RE: Superconducting tesla coil...

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

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.