The "electromagnetic field" associated with various particles
has a
unique property that most folks don't hear about outside of
college
physics lectures.
We start with the simple electric field of a single particle, such
as
a negatively-charged electron. Lots of folks know that if the
electron moves, it
becomes associated with an overall magnetic field, too. (Even
while "still" it has a magnetic field associated with its "spin",
but
I'm ignoring that here, and only talking about large-scale
motion
of the electron.)
The unique thing, that usually isn't explained, relates to the
origin
of that magnetic field. It is actually the SAME electric field as
before! It is just that when the electron moves, its overall
electromagnetic field can be PERCEIVED two different ways,
partly as an electric field, and partly as a magnetic field. The
magnetic field is a "relativistic effect" associated with the
motion
of the electron. IF the electron moved nearly at lightspeed,
practically ALL of its electromagnetic field would be perceived
as
a magnetic field, while only a tiny fraction of it would be
perceived as an electric field.
The next relevant item is an electric current moving through a
wire. We know there is an associated magnetic field, and we
also
know that huge numbers of moving electrons are contributing to
that magnetic field (something like ten-to-the-eighteenth-
power
electrons in one ampere of current), but most people don't think
about how fast the electrons are moving in the wire. Logically,
if
they could move faster, then per the preceding paragraph, the
magnetic field would be stronger!
Well, it turns out that in ordinary wires, the electrons move at
only a couple of MILLIMETERS per second....
Now we can get to the Idea here. An "electret" is a solid object
that has a permanent electric charge, similar to a permanent
magnet. They can exist in any ordinary shape, so let's imagine
one shaped like a piece of tubing.
Inside an electret, the electrons are "fixed" and cannot move
(else
they would quickly escape, since they all electrically repel each
other!). However, the OVERALL electret is a thing that can
move....
Let's put this tubing over part of the length of a rod, and turn
the
rod like an axle. All the electrons in the electret are now
moving,
much as if we had an ordinary electric current moving inside a
"single turn coil". But we can make THESE electrons move LOTS
faster than mere millimeters per second!
Alas, while we can imagine creating a super-strong magnetic
field
this way, There Is A Problem, which is why this Idea is Half-
Baked. See that number of electrons in 1 ampere of electric
current? 1,000,000,000,000,000,000 is a LOT of electrons! The
electret, however, likely contains a few million electrons at
most. They electrically repel each other too much, to stuff
more
of them into the electret!
Our spinning-electret-tube magnet is going to be far feebler
than
we want. Oh well.
BUT --see that subtitle, about a variation on the theme?
Let's now take a tubular piece of metal, and cool it down to
become superconductive. We can now induce a LARGE flow of
electrons moving around the circumference of the tube. It
automatically has a strong magnetic field....
Now put THAT tubing on the length of rod, and start turning it
like
an axle. For maximum (theoretical) effect, we want the
overall
motion of the tube to be in the same direction that the
electrons
are moving inside the superconducting material of the tube.
ALL those already-moving electrons are now moving WAY faster
than mere millimeters per second, and so we should get a super-
strong magnetic field, right?
ALAS! All the POSITIVE charges (on protons) in the tubing are
also moving in
the same direction as the electrons, and their motion generates
a
CANCELLING magnetic field! The Idea is STILL Half-Baked!
But that just makes it Perfect for posting here. Enjoy!
=================
Added June 4, 2015
Here is another variation of this Idea. We start with the tubular
and axially-rotating electret magnet, the first invention
described in this Idea. We place it in a vacuum, and install a
nearby electron gun. We want to be able to "inject" an extra
electron or two (or more) into the body of the electret, and we
will probably have to shoot the electron at pretty high speed
into the electret, to overcome the physical material's ability to
lock electrons into place, inside the electret (have to get
through the surface of the material).
I'm going to add a couple of links, first because of an annotation
by [pashute], and second because of this variation of the initial
Idea. You might want to examine that 2nd link before
continuing reading here.
The relevant thing about the "pinch effect" is that as electrons
move together, their mutual electric repulsion diminishes
somewhat, and their magnetic fields align in a way that tends
to cause the electrons to attract each other.
Now think about that in terms of our INITIAL non-rotating
electret. It has some maximum number of electrons embedded
in it, that can't be increased because they all repel each other
(as previously stated). But when rotating, if their repulsion
decreases, and magnetic attraction increases with speed, we
CAN add some more electrons to it!
That is what the electron gun in the vacuum is for. Think of
this as a kind of "feedback" system. The more the electret
rotates, the more the magnetic attraction of the electrons
tries to overcome their repulsion, and the more electrons we
can add to the electret. ALSO, the more electrons we add to
the electret, the stronger the magnetic field gets, even without
increasing its rotational speed! And AGAIN we become able to
add even more electrons to the rotating electret!
How many electrons can we add, before we reach a limit,
related to the maximum possible speed that the electret can be
roatated, before it breaks apart because of "centrifugal"
stresses? I don't know! How strong will the magnetic field be
at that point? I don't know!
But I do think it might be interesting to find out!