Probably a stupid car question...

[Lissa]

Hi,

OK, I have to be a bit careful here.

high grade switches

Trivial, today. Run of the mill SCRs (silicon controlled rectifiers) have a turn on time of 1.5 to 2.0 µs. Much better than what they had at Los Alamos in '45.

Not so trivial in other countries. You also have to have a special license to get those level of switches. It is monitored very, very closely.

Likewise, the bombs used on Hiroshima and Nagasaki were over the necessary amount of material because of the lack of technology. In Little Boy, the main Uranium pit was almost a critical mass by itself, it took slamming another large piece of Uranium into is to cause the reaction to go. Given it was about 1.5 critical masses, it detonated for about 9 kT. A test reactor used by Los Almos in the 70s was just slightly over a critical mass (it was used for flux experiments) and a sphere with a cylinder cut out of it and said cylinder was allowed to travel through the sphere to test fast flux interactions. Said reactor was taken out to the test range and the cylinder was block to stay in the sphere, needless to say, they got a detonation that was roughly twice what Hiroshima was. Nagasaki was above a critical mass (if I remember what my professors said, it was around twice what was necessary) as they weren't sure if they could get a good enough implossion to detonate the plutonium pit, they did get it to detonate for around 20 kT.

high grade explosives

Comp C and HMX appear to be relatively easy to get in the arms market. I've made my own PETN, nitroglycerin, and trinitrotoluene (and that was when I was in high school). With a little care and a little knowledge, some combinations of those (or mixtures of those) can be used to generate a spherical wave. If you know what you're doing, you can get consistently uniform and pure material.

Right, but one little slip up in the machining process can severly effect the implossion. All of the explosive have to have a near perfect shaped compression with exactly the same force all around, one of the charges being either under or over balance will deform the pit and cause the reaction to fizzle (which can still be powerful, but not as powerful as you might be looking for).

Bah, it only takes C-4, photo strobes and a metal salad bowl. I saw it in a movie!

That movie scared the crap out of me. There were a few errors, but they came damned close (too damn close) to getting it right.

--Pete

What should scare you more is that there are magazines out there with actual schematics and such on how to do it. I've seen a few and that's far more scarey that these magazines are accessible by going to a local library and getting them then in how close a movie got.