h a l f b a k e r y
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
or get an account
Anybody remember Plasmagnetic Levitation by
Hovertech? It was supposed to be a levitation technology
that used a UV
laser to ionize the air underneath the vehicle and then
an alternating magnetic field to repel this cold plasma
imparting an upward force to the vehicle.* The same
technique is used in "mass driver" devices some hobbyists
where a capacitor bank is dumped through a pancake
coil, launching a hard drive platter or similar object
the coil into the air. The theory is apparently that the
magnetic field induces a current in the conductive
or hard drive platter), which then generates its own
magnetic field, opposing the applied one. These
fields result in repulsion. It seems to me that this is just
like electromagnetic braking but with the roles and
My idea here is to use that repulsion to repel incoming
bullets. I'm imagining a shield similar in shape, size, and
material to the ones used currently by SWAT teams (so
it's still usable to block any bullets it fails to repel, or in
stops working) with embedded coil(s) and capacitor
bank(s). It also has a pulse doppler radar module built in
cheap (tens of dollars) now. When the radar detects an
incoming bullet (by how it dopples the radar return), it
waits for it
to get close enough (by radar pulse time of flight) and
then fires the repeller. Hopefully, this results in the
dropping to the ground in front of it. I don't expect it to
be strong enough or aimable enough to usefully throw
back at the shooter, but maybe if it was mounted on a
robot arm or similar (or could control the user's muscles)
The expected advantages over a passive shield that
absorbs bullets' kinetic energy with its material are:
- Doesn't wear out as seriously. (The capacitors will wear
out, but they can be replaceable. With a regular shield,
wear out in one spot while still being fine elsewhere, but
at least with some types I expect you have to replace the
- Slows the bullets more gradually, reducing the peak
force applied to the user's hand and arm, reducing
fatigue, or to the
stand if used stationarily, reducing the risk of toppling
and/or enabling the stand to be lighter.
- Stops the bullets without deforming them, enabling
easier forensics on them.
- Might (conceivably but I don't know if even
theoretically) be able to recover energy from the bullets
to recharge its
- Might be lighter, and can more easily be transparent or
even open in the middle, if you're willing to forgo some
It could also conceivably be built into body armor,
vehicle armor, building armor, etc.
N/A [probably around 20062007]
*That was how I understood it, anyway. But PL
apparently evolved from their earlier ferrofluid
which used a hollow cylinder of ferrofluid contained by a
magnetic field to contain a column of pressurized air
supported the vehicle's weight. So maybe PL was
supposed to work that way too, just with plasma
By [Voice]. The idea that prompted me to post this idea after so many years [notexactly, Mar 18 2019]
Electromagnetic Reactive Armor
By [paru]. I found it while browsing the armor category and thought it might have been the same idea, but it's not. [notexactly, Mar 18 2019]
Not happening with a small electromagnet. [James Newton, Mar 21 2019]
||I think a shield is generally considerably larger than a
wristwatch. Also, I'm imagining the bullets approaching the
shield head-on, whereas with the watch, it sounds from the
description that they might be flying past itI can't watch
the video right now.
||I could be wrong but an electromagnet capable of either magnetically or dia-magnetically repelling a bullet in flight would be powerful enough to either pull the iron from your blood and amalgam from your fillings or pop you like a grape as the water tried to exit your relatively stationary body.
||Like I said, I could be wrong, but I don't think so... you're going to need a small nuclear power plant to generate that much electricity and I don't think you'd want to be around when the capacitor discharges that much power.
||The bullet might miss you... but you'd literally be toast.
||I have doubts that this could possibly work, but hereis an alternative:
||Fast computers and cameras calculate the bullet's trajectory; only those bullets likely to reach a target are singled out for EM efffects.
||Bullets, or perhaps miniature whiffle balls,or expandable trees (pointy end first) are then fired at the other bullets, striking them and changing their trajectory to something less likely to hit the target.
||I think this is obvious enough to have been researched previously.