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Comment by robotresearcher | Hacker News Reader

No, the defining characteristic of thermonuclear bomb is a second stage fusion device. The first stage fission device sets off the second stage.

https://en.m.wikipedia.org/wiki/Thermonuclear_weapon

Edit: just acknowledging the funny set of identical replies!

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Oh! My bad =) I should have looked it up first. I always thought it was take the unstable uranium isotope and surround it with a horrible amount of explosive material which was set at a controlled time to pressure the uranium into a cascading reaction. Turns out, I'm running on the 1940's Popeye cartoon explanation =[

You're right but for the name. That's how the fission nuclear bomb works. Then you combine it with a heavy hydrogen fusion stage to get a thermonuclear ('hydrogen') bomb.

No, the person you're replying to is right, the bulk of the energy is from fission. What the fusion does is serve essentially as a "tamper" - it's in a ring around the fissile core and as it explodes it compresses the fissile core. Since the fission rate increases exponentially this tamping dramatically increases the overall energy yield.

I think we all agree that fission AND fusion are involved in a thermonuclear weapon.

No, that is NOT what the 'tamper' is or does. See my (or various other) nearby comments where I describe the actual process, or just read the Wiki article linked in another comment...

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