You don't need to imagine, we can compute it!

Mach 7 is 2382 m/s. 23 pounds is 10.4 kg.

Since k=mv^2: (1/2) * (10.4 kg) * (2382 m/s)^2 = 29504404 Joules.

That's 29.5 MJ, which is 29.5 megawatt-seconds. So it could mean 29.5 megawatts for one second, except of course the rail time is much less than one second. But who cares, let's convert to household units! 29500 kilowatt-seconds is 8.2 kWh. At an average price of US$0.13/kWh, that comes to just $1 worth of electricity to fire a $25000 projectile.

Oh, yeah, the losses. Those are probably 90% or so, so let's say $10. And mark it up a factor of ten because the electricity is on a boat, so $100, and a factor of 50 because it's a weapons system. So ballpark $5000 in electricity TCO to fire the $25000 projectile.

If I recall, one of the huge challenges was handling just that. Specifically, I remember something written on it a few years ago that the device was functional, but due to the overwhelming amperage, each shot fused the system up. And now I'll believe it, given that the video shows the casing partially vaporizing as the projectile is exiting.

There's something incredibly shocking about something exploding without traditional explosive chemistry. Just a monumental arc flash (or something - I don't know if it's the same mechanism).

In the ideal case, the math is pretty simple. The kinetic energy in 1/2MV^2 . (integral from 0 to mach 7) so if you know the weight of the missile...

The Popular Mechanics article from a few weeks back said 6 million amps per shot

http://www.popularmechanics.com/technology/military/4231461