I’ve thought about this before, and speculated it may be a less-aggressive way for Iran to demonstrate potential intent and capability of a modern U or Pl enrichment program, without them actually having to feel the wrath of 90% of the world if they actually pushed hard towards physical weapon development.
Its puts their opponents on notice - “you’ve isolated us, but we’ve shown we can take a few steps along the path - and you know we’ll figure out the rest if we needed to”
Correct me if I’m wrong, but nobody is trying to build a fission bomb, right? Iran et al. are building thermonuclear weapons, which took the US an extra seven years to build/test and probably three or four more years after that to deploy in a reliable air-launched form.
Nobody knows what they are trying to build.
But, it would be foolish from an engineering perspective to try to design and construct an H-bomb before making a working A-bomb.
An H-bomb is many times more sophisticated, and requires a very efficient fission stage, something that a first attempt is unlikely to yield.
My impression was the opposite. They are all (all if we count Iran) building the more primitive gun assembly fission weapons. This is partly supported by the fact that it is uranium enrichment that is the issue, and not access to plutonium.
What matters most is that a weapon works. The perceived need for an atomic weapon capability for a small nation is different to that perceived by a superpower - at least at a matter of scale. There is no need for multiply targeted devices that can be delivered on the other side of the planet.
If you are a small isolated nation, with lots of nearby enemies, or you are locked in an interminable unresolvable conflict with a neighbour, you need protection. And that means the ability to really badly hurt your opponent if things get nasty. Atomic weapons - and really you only need a small number - fit the bill well. The counterpoint is that they are worse than useless as an offensive weapon. Use them for offence and you are pretty much guaranteed to be wiped off the face of the map. But in retaliation for invasion, you have nothing to lose. There is a reason we talk out the “nuclear option” as meaning the last resort, everyone dies, scenario. If you are a basket case nation like North Korea you only need to make the world think you are insane enough to actually consider using them to create enough nervousness in the world to be able to bully well above your weight. You don’t need very powerful or high-tech weapons. They only need be light enough to be loftabe to your enemy’s capital on whatever delivery vehicle you have. For Iran, up until recently this meant Baghdad, although nowadays Riyadh might be higher on their worry list. But you play a difficult game - and the benefits in clearly and verify-ably not having such a capability may actually give you the room to become much stronger, and with it, such strength sidesteps the problems.
You have a fission bomb.
You have the H bomb. In which you use a fission bomb to fuse hydrogen bomb. The fission part of this bomb is just the match for the much larger hydrogen part of the boom.
Fission bomb yields are measured in kilo tons. Hydrogen bombs are measures in mega tons. Or in other words one is roughly a thousand times more powerful than the other.
A THERMO nuclear bomb is a fission bomb that fuses a little hydrogen. That ups the yield a bit. But the main purpose of fusing the hydrogen is allow a more efficient fission bomb. A bare fission bomb actually fissions a few percent of the fissile material. A THERMO nuclear bomb fissiles most of the fissile material.
So, a thermo nuclear bomb is say 25 to 50 times more powerful than a fission bomb. So we are at the 100s of kiloton level.
Hydrogen bombs are often overkill. A pure fission bomb often isn’t quite enough. Hydrogen bombs are big and very complex. A fission bomb can be made fairly small and isn’t as complex (but still pretty damn complex as these things go).
A thermo nuclear bomb is nearly as complex as an H bomb. And maybe more so given the tolerances if you want a smaller bomb.
So, if the Iranians are aiming for a thermonuclear bomb, and aren’t balls to walls funding and engineering it…yeah its gonna take years to get there…particularly if they aren’t doing any actual testing along the way.
I stand properly corrected, I think. Thanks.
Maybe because other countries like Israel will do everything in their power to see they never can build a bomb…
I don’t think your definitions are completely accurate.
A fission bomb derives 100% of it’s yield from Uranium or Plutonium (or a mix).
An H-bomb (or thermonuclear bomb) derives the majority of it’s yield from the fusion of Deuterium (usually in the form of Lithium Deuteride). A side effect of fusion is the production of lots of energetic neutrons, which can act to fission U-238 (which is so cheap that bullets and armor are made from it), increasing the yield again very inexpensively. This is a”three-stage” (fission-fusion-fission) bomb.
A third type of bomb is a “boosted fission” bomb, where a small amount of tritium is fused to provide the neutrons to fission the U-238 tamper. In this type of bomb is the staple of the US arsenal, and allows “dial-a-yield,” where the amount of Tritium introduced can be controlled, to vary the yield over quite a large range.
Note that the largest bomb ever tested (the Tsar Bomba), was a three-stage device, with the third stage left off. If the U-238 tamper had been included, it would have doubled the yield, and at the same time introduced more fallout than all the devices tested to date.
Minor nitpick, but the deuterium and tritium in a boosted fission bomb actually fuses in the pit of an implosion weapon and in essence, supercharge the fission reaction by throwing a LOT more fast neutrons into the mix at the very center of things than you normally get from an implosion. The fusion reactions only add about 1% to yield, but the neutrons given off cause more of the pit to be fissioned before it comes apart as part of the nuclear explosion, making it more efficient. External neutron sources are also used to boost the fission reaction in a similar fashion.
Dial-a-Yield bombs tend to use variable amounts of fusion fuel for boosting, along with different timings and intensities of the external neutron initiators to vary the yield of the primary, and I imagine, the yield of the secondary as well.