How do hydrogen bombs work? - Real Chemistry

In this video we discuss how hydrogen bombs work. This builds off of content from two previous videos on nuclear chain reactions and the uranium and plutonium bombs.

[RealChemistryVideos]

In the video I say "Mass is destroyed" which has led to no small bit of controversy. This is not the standard way to phrase what happens - its more common to say "mass is converted into energy."


Why would we not use the word "destroyed"? The main reason, I think, is because it sounds like it contradicts the law of conservation of mass. However, the law of conservation of mass really includes the possibility of interconversion of mass to energy. So where we had mass, it is no more - but this doesn't violate the conservation of mass/energy.

[jeffreyyoung]

There is a cool story about the 'plastic' used in the making of the bomb.

When the bombs were found to be approaching the end of their life and they wanted to overhaul them, the foam used was lost to history and they had to reinvent the foam. The first batches ended up failing due to the foam being too pure! They found an impurity that was needed to make the foam work, and it was added into the foam and then it worked!

[KomradZX]

Hey this is by far the best video I found explaining hydrogen bombs. I watched about 3 minutes of 2 different videos then found this one. First video I felt that actually taught me something. You earned my sub! Cheers from St. Louis Missouri

[TheTransporter]

The nutty part about the nuclear stuff: *EVERYTHING* described in this video happens after the the primary H.E. ignites, but before that chemical explosion blows the hohlraum & bomb casing apart. Even with the explosive lensing, quite a bit of that blast force will travel outward, but what compresses the fission primary is the detonation wave, which is moving at ~5km/s or higher, depending on the particular H.E. being used. But the relativistic speeds at which the nuclear stuff happens easily overtakes the chemical blast. Just bonkers.

[Evan_Bell]

Good introductory video, but I'd like to add some details.
Fission devices have produced 0-500kt yields. That 20kt figure is arbitrary.
Thermonuclear weapons have produced 1-56800kt.
Thermonuclear primaries can be pure uranium, pure plutonium or uranium/plutonium composite. Weapons with cores of all these materials have been produced.
Devices have been demonstrated that use pure fusion secondaries.
The fusion fuel for all but a very few early devices is lithium deuteride. Lithium isotopic compositions of 7.59% Li6 (natural) to 95% Li6 have been used.
The tamper need not be uranium 238.
When uranium is used, isotopic compositions of 0.3% U-235 to 37.5% U-235 have been used. Lead, lead-bismuth eutectic and gold are also known to be used.
It's not technically accurate to speak of x-rays being reflected off the hohlraum. They penetrate into the hohlraum, deposit their energy, heating up a thin inner layer of the hohlraum, which then re-radiates thermal radiation.
The prime mechanism by which the primary's radiant energy is converted into internal energy of the compressed secondary is ablation.
A thin layer of the secondary pusher is superheated to a plasma, just as the hohlraum is, this plasma is of higher pressure than the deeper cold pusher and interstage foam plasma, thus it expands. This produces a recoil reaction imploding the secondary. Once the radiation diffusion wave has penetrated some distance (on the order of 1mm) into the pusher, it becomes subsonic and hydrodynamic separation occurs producing a classical shock which initially impulses the secondary pusher, which is then followed by that produced by the ablation pressure.
The interstage radiation pressure and that produced by the sparkplug do not compress the fusion fuel simultaenously. The secondary is impulsed by the interstage, then undergoes freefall implosion, compressed the cold fusion fuel, then the sparkplug, initiating fission, which heats the compressed fusion fuel.
Initially, the wave from the sparkplug into the fusion fuel will be in the form of a supersonic radiation diffusion wave, thus it will not compress the fusion fuel, I've yet to run the numbers to determine whether hydrodynamic separation ever occurs in the fusion fuel.

[hacknwack]

Thank you so much, i just bought mine and i was trying to figure out how it works!

[dkd]

Minor nit - When the fissile nucleus splits, it does more than "falls apart". The fission fragments are driven apart by electrostatic repulsion. This happens at relativistic speeds, resulting in millions of degrees of heating.

[arunjoshi]

hats of man. such technicality at such ease.

[pkunberger]

This video has personal relevance. Back in 79 the Progressive Magazine published an article on how H-bombs worked. The government went to court and got an order preventing publication - first case of priority restraint of the press. As part of the ACLU’s defense of the Progressive I went to Los Alamos with a friend who was an independent expert and discovered declassified documents from the 1950s that were far more revealing than what the Progressive was going to publish. The discovery of the documents in the public access section of the Los Alamos Lab library blew up the government’s case. It was pretty tense when we bought a copy of the Washington Post at the airport and the front page article about it referenced hit the“FBI investigating violations the Atomic Secrets Act” and “20-life”. A long flight to say the least. In the event nothing happened to us as the documents were clearly declassified. Los Alamos got in trouble and they even had Senate hearings about it. Now this is on YouTube.

[The_CGA]

The “more detailed information” that you call “classified” is now bouncing around the internet, it turns out having the info be open source helps the public unders how close or far places like Iran and North Korea are from making their own. See Scott Manley’s series on nukes for an examplr

[USViper]

The "yellow foam" is actually called "FOGBANK" and it's clear. It's highly classified but more than likely used as a plasma to aid in reaction.

[taraswertelecki]

The outer shell of thermonuclear weapons could also be made of U-238, which confines the detonation of the primary and secondary stages for just a little longer. In the process, U-238 nuclei capture fast neutrons from the first two stages and fissions itself, greatly magnifying the blast a creating most of the nuclear fallout from the blast.

[HelloJamesBond]

Great video and explanation, without any background in this i could understand it perfectly. Cheers

[TheTransporter]

I believe Little Boy was deployed first. Subscribed anyway.

[beryllium]

Ahh those BOSCH Plutonium spark plugs! I'm gonna swap my NGK Iridiums out for some of those.

[hvnterblack]

Three phase bomb is called "przekładaniec", it has layers. Inside is standard fission material, outside too. That middle layer has pressure of inner and outer layer releasing enormous mass of enrgy, forces it to fission. Squeze fission material by two nuklear loads is enough to make it work. Then goes boom.

[Krebssssssss]

The explanation makes these weapons all the more terrifying.

[taras]

There is no limit to the blast yield of a thermonuclear bomb, it's just a matter of incorporating enough fusion fuel and stages to achieve the intended yield.

[bozokillerv]

Very easy to take in the information, unlike other videos.

[EdMcF]

I read long ago that Fe (Iron) is the most stable nucleus, so fusing towards Fe or splitting down to it is the way to go. Yields may vary.