Minimum mass for Implosion type thermonukes?

I did change the limit in game, what I want to know is if there is a lower limit to mass capable of going supercritical in nukes in reality.

Well check this out boys:

www.pravdareport.com/science/tech/19-11-2014/129079-atomic_bullets-0/

Now it is Pravda and I don't see any citations, but this gives me some ideas...

Damn, beat me to it. Is Ca-252 availabe? If only I didn't have work today...

How's that puppy handle btw?

There generally is a minimum mass below which a nuke cannot (or I suppose more accurately, is extremely unlikely to) detonate, but this does vary based on what the fissile material is and what conditions it's under.

It's basically a race to release neutrons faster than they can escape, combined with a probability game of getting those neutrons to hit and split atoms. So for example, if you had a theoretical 100% efficient neutron reflector, you could shrink the critical mass significantly because neutrons would just build up endlessly until they reach the critical neutron flux, at which point it would go boom if there's enough unsplit fissiles left to do so.

If you had an extremely unstable isotope that was easily split by low-energy neutrons, and released tons of neutrons when it did split, that would also have a very low critical mass. It would also be highly radioactive, so your scientists would probably be a little reluctant to work with it and it would have a very short shelf life, which would cause logistical problems.

Of course, since safe handling and shelf life are not a concern in CoaDE we could probably use artificial superheavy elements whose half-lives are measured in miliseconds such as Oganesson (atomic number 118) or the hypothetical Ununennium (number 119). Though since these elements can only be made in particle accelerators and they decay almost instantly, I'm sure assembling even a few grams of those would be quite a tricky proposition. I'm sure a softer sci-fi setting could do funny things with stasis fields though.

My understanding is that IRL it's very difficult to get densification ratios better than 1/3 or so (source, ctrl-f "achievable factors range", see also, ctrl-f "extreme compression").

Mass and volume-minimized bombs take advantage of low-pressure compression mechanisms like squashing subcritical geometries (hollow, oblong, etc.) into supercritical spheres and maybe that convenient plutonium phase transition. That minimizes the amount of explosive required and the size of the lens system, but gives poor efficiency and requires a lot of fissile material per warhead.

Our ability to make ridiculously high compression ratio bombs is somewhat counteracted by the much greater critical masses (60 kg for Pu-239 in CoaDE, 10 kg IRL). It actually helps for high-yield bombs, since you can pack a lot more fissiles in before encountering criticality problems, but I've found the combat effectiveness of high-yield bombs to be very underwhelming. Several low-yield devices detonated together does more damage and is far cheaper. It also seems seems like the explosive is used as reaction mass for the bomb, so a 50 kt bomb does more damage than a 1.35 Mt bomb, at less than half the mass and way lower cost.

Fuck.

Now I want to lower the limit.txt and shove these mini nuke into my cannons and EM guns because holy shit what 1 ton of TNT in less than 15 gram package.