On Jul 18, 4:07 am, " wrote:
On Jul 16, 6:52 am, Dirk Bruere at NeoPax
wrote:

Uncle Al wrote:
Dirk Bruere at NeoPax wrote:
I once did a calculation for a NG, sci.military.moderated IIRC,
concerning the lethality of the hypothetical weapon given a beam pulse
energy comparable to the muzzle energy of a conventional handgun (about
700J).

The question I could not answer concerned its effect on the user of the
weapon. Would there be enough back scatter from the air at the muzzle
and along the beam path to seriously endanger the health of the firer?

How short is the pulse?

An M16A2 rifle has a muzzle velocity of 2800 ft/sec. The bullet
travels one foot in 0.3571 msec. 700 J in 0.3571 msec is 1.96 MW. The
air would massively ionize. Worry about thermal and UV burns, then
soft x-ray backscatter.

Since we were talking handguns the velocity would be around 1/3 of that
if we stuck to the analogy. However, since we do not have to worry too
much about beam drop (as opposed to bullet drop) the real time to
consider is time on target. Since I doubt anyone could dodge such a beam
lasting 10mS, we now have a power of 70kW. For simplicity we can assume
a beam diameter of 10mm.

70 kW of what, photons? If so, what wavelength(s)?

Sorry, "senior moment"; title of thread = "Gamma Ray Gun". Anyway,
apparently gammas are very easily absorbed by air. Perhaps "absorbed"
isn't exactly appropriate, considering there are gamma-ray
observatories being built on Earth's surface that don't actually look
for gammas but rather the particle showers resulting from what happens
when incoming gammas strike air.

So, having lowered the pulse intensity below the threshold of
"ionize the air in front of the muzzle into a lethal mirror", you have
your pulse of prompt gammas pretty much converted to lower-energy
photons and fast-moving electrons, muons, and who knows what other
charged particles within a very short distance.

Perhaps you could think about some sort of "afterburner"
electrostatic muzzle add-on that would encourage the charged particles
to emit their contribution to the final beam in the general direction
of the target rather than back at the wielder?

Mark L. Fergerson