Re: Electric Current Turbulence

[John Denker <jsd@MONMOUTH.COM>]

At 05:42 AM 10/22/99 -0400, Ed Schweber wrote:
>   I have never heard of electric current turbulence but now that the
> question was posed I can't think of any reason why it shouldn't exist.
>
>   Is there ever turbulence. If not, why not? If it does exist, is there be
> a measurable potential difference across the junction?


The general topic you raise is called MagnetoHydroDynamics -- the motion of
charged fluids.  A search such as
  http://www.altavista.com/cgi-bin/query?pg=aq&q=mhd+near+turbulen*
will turn up hundreds of hits.

A canonical example is the solar wind, which consists of flowing charged
particles.  When two currents of solar wind meet, you can expect turbulence.

OTOH in ordinary wires, you have a small region of space containing large
numbers of electrons moving very slowly with very little mass, very little
momentum, and rather short mean-free-times between giving up (to the
lattice) what little momentum they had.  This makes a Reynolds number waaay
too small to produce turbulence.

See _The Feynman Lectures on Physics_ volume II chapter 41 for some
discussion of Reynolds numbers.

I've never seen an elementary discussion of MHD and I'm not sure such a
thing is possible.  It's tremendously complicated.

______________________________________________________________
copyright (C) 1999 John S. Denker             jsd@monmouth.com