Re: Rail gun
- From: "Brian McDermott" <bjmcder@xxxxxxxxx>
- Date: 30 Aug 2006 06:41:46 -0700
boss_not_in@xxxxxxxx wrote:
G. R. L. Cowan wrote:
Ok, time for a little math. We're going to assume the following:
-a solid 2 gram (1 mole, 6.02x10^23 atoms) Deuterium ice "bullet" fired
at a stationary Deuterium ice target;
-A fusion burn temperature of 20 keV, or roughly 220 million degrees.
In order to get the atoms in the bullet to fuse with those in the
target, the kinetic energy of each atom in the bullet needs to be
20keV. We convert 20,000eV into Joules:
(20,000)*(1.6x10^-19)=3.2x10^-15 Joules per atom
Because the bullet has a mass of 2 grams (0.002kg), it is the
equivalent of one mole of deuterium, and thus contains 6.02x10^23
atoms. Thus, we find the total kinetic energy in the bullet:
(3.2x10^-15)(6.02x10^23)=1.9x10^9 Joules
That's a ton of energy, and I mean that literally because one ton of
TNT is about the same as 4.184x10^9 joules. But let's take this to
completion and solve for velocity:
E=(1/2)mv^2
manipulating, we get:
V=sqrt(2E/m)
V=sqrt(2(1.9x10^9)/0.002)
V=1.4x10^6 meters/second
That's just over a million meters per second, about 1400 kilometers per
second, 875 miles per second, or nearly 1 percent the speed of light.
Earth's escape velocity is 11 kilometers per second, so you're looking
at a muzzle velocity over 100 times greater than that.
Each D-D fusion releases about 3meV worth of energy. Thus, one mole of
fused deuterium is worth about 3x10^11 Joules. You'd have a net gain of
2 orders of magnitude if you could get such a system to work, assuming
no losses and 100% efficiency.
Possible? Maybe. Plausible? Probably not. Practical? I'll let you
answer that for yourselves.
QED,
Brian McDermott
When you calculate the amount of energy release
You should include the mass of the target.
If the target is also 2g
Total mass involve would be mass of target + mass of bullet
that is 4g. >But there is no reason to limit the mass of target to 2g,
you can put in 5g 10g 100g, 200kg... deutrium in the target.(I means it is
a
variable) >Once the bullet hit the target, fusion reaction begin at the
point of impact
which realease huge quantity amount of heat.
That will heat-up the duetrium around causing all duetrium in the target
involve in fusion reaction.
This type of fusion is of course is 'inertial confinement fusion' >By
ajusting the mass of the target, you can control the amount of energy
release during each 'fire'
Also the mass of the bullet can be adjust
there is no reason why we have to use 2g.
If 0.1g is able to ignite the fusion reaction,
then use 0.1g, because less bullet mass means less energy input is required
If people can spend few billion of dollar for giant accelerator machine to
accelerate atomic particle to 90% of light speed.
Why can't we spend another few billion for another giant accelerator machine
to accelerate matter of 1g or 2g to the speed of 1% of light speed?
Fine. Just try and extract the energy from the resulting 100 ton
equivalent explosion. In reality, the bullet will blow right through
the target with little decrease in velocity. Ever heard of inertia?
Once it's moving, it's not gonna want to stop.
Accelerating a few million (10^6) atomic particles in an accelerator is
a helluva lot different than accelerating 6x10^23 of them. That's a 17
order of magnitude difference; read 100 QUADRILLION times more
difficult.
You're trying to set off a firecracker by hitting it with a sledge
hammer rather than by simply lighting the fuse.
.
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