[SBE] Liquid Nitrogen...

[Cowboy]

On Thursday 07 May 2009 07:24 am, Edwin Bukont wrote:

>  

>   The increasing heat spreads quickly beyond 

>  the bad connection and causes failure of a substantial portion of the 

>  magnet section. I believe they refer to this overall catastrophic event as 

>  a 'quench'               


 Almost.
 Due the proximity to absolute zero, the wires go super conducting.
 As such, once a current is started in the coils, "inertia" will keep
 the current flowing, and the magnetic field, almost indefinitely.
 The dissipated power is equal to I^2*R so when R=0 no power is
 dissipated, but that does not mean the circulating current is also zero.
 It MAY be many hundreds, or thousands, of amps.

 Quenching is when a resistance is provided in the path of the current
 ( as you describe a faulty connection ) or the field, to dissipate that current
 or field.
 In the case of a faulty connection with any resistance at all, ALL of the
 energy in the field is returned to the circulating current path, and
 ALL of the energy is dissipated within the resistance of that bad connection.
 The result is somewhat more dramatic than connecting fine wire solder
 to an arc welder.

 If you thought a bullet burn-out in a class C FM was bad, then like the
 song says, "You ain't seen nuthin yet."
 Your "spreads quickly" choice of words is something of an under-statement.

-- 
Cowboy

http://cowboys.homeip.net

If a putt passes over the hole without dropping, it is deemed to have dropped.
The law of gravity holds that any object attempting to maintain a position
in the atmosphere without something to support it must drop.  The law of
gravity supercedes the law of golf.
		-- Donald A. Metz