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I was under the impression H-bombs utilized hydrogen in the atmosphere to feed its fusion reaction. If you send it up to "outer space" it wouldn't have any fuel

by ythn 9y ago

I was under the impression H-bombs utilized hydrogen in the atmosphere to feed its fusion reaction. If you send it up to "outer space" it wouldn't have any fuel to fuse?

Robotbeat 9y ago
Not at all. The "hydrogen" in hydrogen bombs is in deuterium (proton plus a neutron) and tritium (proton plus two neutrons), both isotopes of hydrogen. Deuterium is stable, but tritium is not. Tritium must either be maintained as it decays (into Helium 3) by topping it off or bred in the nuclear explosion itself from lithium capturing a neutron. In either case, the source material is contained in the bomb itself, so you can initiate the bomb anywhere. Also, the atmosphere contains almost no hydrogen (except a little bit in the form of water vapor).
lb1lf 9y ago
A H-bomb is a BYOH (Bring Your Own Hydrogen) device - the weapon includes a helping of deuterium (hydrogen with an extra neutron). The fusion reaction requires an awful lot of energy to get going, so it basically uses a fission bomb as a detonator.
deleted 9y ago
[deleted]
TheAdamist 9y ago
no, there are hydrogen isotopes in the bomb, deuterium & tritium. Not to mention there is no appreciable amount of hydrogen in the atmosphere anyway. https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon http://climate.ncsu.edu/edu/k12/.AtmComposition http://climate.ncsu.edu/edu/k12/.AtmComposition
- InclinedPlane 9y ago
  Humidity is considered to be separate from "the atmosphere", as it varies from about 0-4%. Humidity contains Hydrogen since water is H2O.
astebbin 9y ago
I'm not sure why you've been downvoted, as your question looks like an honest one, and the answers are very informative. I certainly learned something new from the replies. Thanks for asking!
- dboreham 9y ago
  Well, perhaps because anyone with a 6th grade education knows there is essentially no Hydrogen in the atmosphere? (~0.5ppm)
  - reitanqild 9y ago
    Don’t overestimate education systems and peoples ability to learn from them :-) Edit: now I'm puzzled why this is collecting downvotes. :-)
  - mikeash 9y ago
    That's an odd thing to "know" considering that the amount of water vapor in the atmosphere is measured in parts per hundred, and a substantial portion of water vapor is hydrogen.
  - jack9 9y ago
    H2 is an assumption you've made. When talking about a nuclear explosion. There is hydrogen in a number of compounds (notably water and hydrogen sulfide) present in the atmosphere that could be relevant sources. The ppm being incidental is another issue. You've been unnecessarily condescending to an honest question.
  - saalweachter 9y ago
    That's honestly the less important part. Even if the atmosphere were pure hydrogen (whether protium or deuterium or tritium) you would not build a hydrogen bomb without its own encapsulated hydrogen fuel source. The black magic of a hydrogen bomb is that it focuses the explosive energy of a fission bomb to ignite a fusion explosion. Doing so requires a very specific configuration; any hydrogen on the outside of the bomb, regardless of its concentration, would not reach the appropriate temperature/pressure to fuse.
pjmorris 9y ago
Others have answered well, but if you want to dig deeper, Richard Rhode's two books 'The Making of the Atomic Bomb' and 'Dark Sun' should more than cover what most non-physicists need to know.
mikeash 9y ago
Other comments mentioned deuterium and tritium, but didn't mention why those are used, which is also interesting. Plain old hydrogen is really, really, really difficult to fuse. Plain hydrogen nuclei are just single protons. When you squish two of them together, you get helium-2, which is unstable and immediately decays. It can either decay back into two protons, or it can decay into deuterium, which is a proton and a neutron, by emitting a beta particle which converts one of the protons to a neutron. The second reaction is really unlikely, so the helium-2 almost always decays back into hydrogens. That means that pure hydrogen fuses extremely slowly. That works out in, for example, the Sun, where tremendous heat and pressure is maintained for billions of years. It doesn't work so well in a bomb which can only maintain fusion-level temperatures and pressures for tiny fraction of a second. Thus, fusion bombs always use deuterium or tritium. Practical bomb designs typically don't use those directly (hydrogen is a pain to work with), but rather use lithium turns into deuterium or tritium in the neutron-rich environment of a detonating bomb.
InclinedPlane 9y ago
Fusion bombs use Deuterium and/or Tritium (in modern bombs the Tritium is bred from neutronic reactions with Lithium) which are isotopes of Hydrogen, that's where the name "Hydrogen bomb" comes from. The fusion fuel capsule is compressed using the power of a fission bomb, which is enough to initiate fusion reactions. Ordinary Hydrogen in the atmosphere would not be of sufficient density to allow for significant fusion reactions. Also, Hydrogen-1 is very much more difficult to fuse than Deuterium/Tritium so even contained in a capsule it would make a quite ineffective bomb.
- arethuza 9y ago
  As far as I recall, the secondary in an H-bomb is indeed compressed by the fusion boosted fission of the primary but this then initiates a fission reaction at the core of the secondary where there is a fission "spark plug". So the lithium deuteride fuel is caught between the incoming compression driven by the primary and outgoing explosion of the secondary spark-plug. When the fusion fuel burns the resulting neutrons are used to fission the tamper of the secondary and it's this fission is the main energy source for most H-bomb designs.
  - InclinedPlane 9y ago
    Yes, inside the fusion fuel capsule there is typically a small amount of fissile material. The fusion capsule is compressed through the very strong forces from the ablation of the capsule's outer material. This compresses the fusion fuel as well as the "sparkplug" inside. The sparkplug doesn't need to contain much fissile material compared to an ordinary fission bomb core because the high degree of compression makes it easier to achieve critical conditions. The sparkplug explodes as a fission bomb, injecting heat energy into the fusion fuel capsule and driving up the conditions (temperature and pressure) which cause fusion reactions. It also injects neutrons which kickstarts the breeding of Tritium from Li-6 and Li-7. Sometimes the "pusher" around the fusion fuel capsule is also made of fissile material which gets compressed, or imploded, just like a normal fission bomb core, but with much higher forces and so much greater efficiency and effectiveness. Additionally, while Uranium-238 is not normally fissile it can be fissioned with high energy neutrons. The "problem" with U-238 is that the energy range of neutrons that induce fissions only partly overlaps with the natural energy range of neutrons produced by fission reactions. Meaning that on average a given neutron emitted by a U-238 fission will cause fewer than 1 additional fissions, so it can't self-sustain a neutron induced fission chain reaction (which, I guess, is a good thing, otherwise nuclear bombs would be nearly trivial to make). However, fusion reactions generate very high energy neutrons, essentially all of which can cause fission in U-238. For this reason many thermonuclear weapons have a natural or depleted Uranium casing. Fission in the casing typically doubles the yield of the weapon compared to the yield from the primary/secondary fission/fusion reactions. All of this can be dialed to suit different desires for bomb production or yield. For example, the "Tsar Bomba" was a 100 megaton 3 stage thermonuclear warhead design, it was tested without a fissionable Uranium outer casing to avoid production of nearly 50 megatons worth of fission product fallout over the test site (which was in Russia), as a result it exploded at around 50 MT yield, almost all of which (97%) was from fusion reactions. On the other hand, you have a device like the W-88 which is an incredibly compact warhead carried on US SLBM submarines. It is a thermonuclear warhead but you could also look at it as a two stage fission-fission device with a heavily fusion boosted secondary, as most of the yield comes from fission in the secondary and the casing.
jloughry 9y ago
As others have already explained well, hydrogen in the air doesn't contribute to the explosion. But what does make a big difference is the air around the bomb---a nuclear explosion in space is way different from one in atmosphere. X-rays from the nuclear reaction heat surrounding air to many millions of degrees [1] and that's what causes (most of) the fireball you see. In space, the only matter available to make a fireball is the weapon's structure, probably only a few hundred kg, and that dissipates and cools rapidly. Nuclear-armed air intercept missiles were built in the nineteen-fifties and sixties that depended for effectiveness on being in air to generate the necessary blast effects to kill a bomber with relatively inaccurate aiming, but in space, a nuclear explosion almost needs be a contact hit to do much mechanical damage...discounting nuclear radiation effects, of course. [1] Fahrenheit, Celsius, Kelvin...it makes no difference.
- computerex 9y ago
  > ...discounting nuclear radiation effects, of course https://history.nasa.gov/conghand/nuclear.htm https://history.nasa.gov/conghand/nuclear.htm > Third, in the absence of the atmosphere, nuclear radiation will suffer no physical attenuation and the only degradation in intensity will arise from reduction with distance. As a result the range of significant dosages will be many times greater than is the case at sea level. With such weapons the lethal radii (from nuclear radiation) in space may be of the order of hundreds of miles.
  - jloughry 9y ago
    I didn't know that. Thanks! Also: Second, thermal radiation, as usually defined, also disappears. There is no longer any air for the blast wave to heat and much higher frequency radiation is emitted from the weapon itself. So more of the energy of the bomb remains in the x-ray or gamma portion of the spectrum---penetrating radiation, hard to shield against---in addition to the longer effective range.
tw04 9y ago
If that were the case the first one would've killed us all.

by ythn 9y ago

I was under the impression H-bombs utilized hydrogen in the atmosphere to feed its fusion reaction. If you send it up to "outer space" it wouldn't have any fuel to fuse?

Robotbeat 9y ago

Not at all. The "hydrogen" in hydrogen bombs is in deuterium (proton plus a neutron) and tritium (proton plus two neutrons), both isotopes of hydrogen. Deuterium is stable, but tritium is not. Tritium must either be maintained as it decays (into Helium 3) by topping it off or bred in the nuclear explosion itself from lithium capturing a neutron. In either case, the source material is contained in the bomb itself, so you can initiate the bomb anywhere. Also, the atmosphere contains almost no hydrogen (except a little bit in the form of water vapor).

lb1lf 9y ago

A H-bomb is a BYOH (Bring Your Own Hydrogen) device - the weapon includes a helping of deuterium (hydrogen with an extra neutron). The fusion reaction requires an awful lot of energy to get going, so it basically uses a fission bomb as a detonator.

deleted 9y ago

[deleted]

TheAdamist 9y ago

no, there are hydrogen isotopes in the bomb, deuterium & tritium. Not to mention there is no appreciable amount of hydrogen in the atmosphere anyway. https://en.wikipedia.org/wiki/Thermonuclear_weapon https://en.wikipedia.org/wiki/Thermonuclear_weapon http://climate.ncsu.edu/edu/k12/.AtmComposition http://climate.ncsu.edu/edu/k12/.AtmComposition

InclinedPlane 9y ago
Humidity is considered to be separate from "the atmosphere", as it varies from about 0-4%. Humidity contains Hydrogen since water is H2O.

astebbin 9y ago

I'm not sure why you've been downvoted, as your question looks like an honest one, and the answers are very informative. I certainly learned something new from the replies. Thanks for asking!

dboreham 9y ago
Well, perhaps because anyone with a 6th grade education knows there is essentially no Hydrogen in the atmosphere? (~0.5ppm)
- reitanqild 9y ago
  Don’t overestimate education systems and peoples ability to learn from them :-) Edit: now I'm puzzled why this is collecting downvotes. :-)
- mikeash 9y ago
  That's an odd thing to "know" considering that the amount of water vapor in the atmosphere is measured in parts per hundred, and a substantial portion of water vapor is hydrogen.
- jack9 9y ago
  H2 is an assumption you've made. When talking about a nuclear explosion. There is hydrogen in a number of compounds (notably water and hydrogen sulfide) present in the atmosphere that could be relevant sources. The ppm being incidental is another issue. You've been unnecessarily condescending to an honest question.
- saalweachter 9y ago
  That's honestly the less important part. Even if the atmosphere were pure hydrogen (whether protium or deuterium or tritium) you would not build a hydrogen bomb without its own encapsulated hydrogen fuel source. The black magic of a hydrogen bomb is that it focuses the explosive energy of a fission bomb to ignite a fusion explosion. Doing so requires a very specific configuration; any hydrogen on the outside of the bomb, regardless of its concentration, would not reach the appropriate temperature/pressure to fuse.

pjmorris 9y ago

Others have answered well, but if you want to dig deeper, Richard Rhode's two books 'The Making of the Atomic Bomb' and 'Dark Sun' should more than cover what most non-physicists need to know.

mikeash 9y ago

Other comments mentioned deuterium and tritium, but didn't mention why those are used, which is also interesting. Plain old hydrogen is really, really, really difficult to fuse. Plain hydrogen nuclei are just single protons. When you squish two of them together, you get helium-2, which is unstable and immediately decays. It can either decay back into two protons, or it can decay into deuterium, which is a proton and a neutron, by emitting a beta particle which converts one of the protons to a neutron. The second reaction is really unlikely, so the helium-2 almost always decays back into hydrogens. That means that pure hydrogen fuses extremely slowly. That works out in, for example, the Sun, where tremendous heat and pressure is maintained for billions of years. It doesn't work so well in a bomb which can only maintain fusion-level temperatures and pressures for tiny fraction of a second. Thus, fusion bombs always use deuterium or tritium. Practical bomb designs typically don't use those directly (hydrogen is a pain to work with), but rather use lithium turns into deuterium or tritium in the neutron-rich environment of a detonating bomb.

InclinedPlane 9y ago

Fusion bombs use Deuterium and/or Tritium (in modern bombs the Tritium is bred from neutronic reactions with Lithium) which are isotopes of Hydrogen, that's where the name "Hydrogen bomb" comes from. The fusion fuel capsule is compressed using the power of a fission bomb, which is enough to initiate fusion reactions. Ordinary Hydrogen in the atmosphere would not be of sufficient density to allow for significant fusion reactions. Also, Hydrogen-1 is very much more difficult to fuse than Deuterium/Tritium so even contained in a capsule it would make a quite ineffective bomb.

arethuza 9y ago
As far as I recall, the secondary in an H-bomb is indeed compressed by the fusion boosted fission of the primary but this then initiates a fission reaction at the core of the secondary where there is a fission "spark plug". So the lithium deuteride fuel is caught between the incoming compression driven by the primary and outgoing explosion of the secondary spark-plug. When the fusion fuel burns the resulting neutrons are used to fission the tamper of the secondary and it's this fission is the main energy source for most H-bomb designs.
- InclinedPlane 9y ago
  Yes, inside the fusion fuel capsule there is typically a small amount of fissile material. The fusion capsule is compressed through the very strong forces from the ablation of the capsule's outer material. This compresses the fusion fuel as well as the "sparkplug" inside. The sparkplug doesn't need to contain much fissile material compared to an ordinary fission bomb core because the high degree of compression makes it easier to achieve critical conditions. The sparkplug explodes as a fission bomb, injecting heat energy into the fusion fuel capsule and driving up the conditions (temperature and pressure) which cause fusion reactions. It also injects neutrons which kickstarts the breeding of Tritium from Li-6 and Li-7. Sometimes the "pusher" around the fusion fuel capsule is also made of fissile material which gets compressed, or imploded, just like a normal fission bomb core, but with much higher forces and so much greater efficiency and effectiveness. Additionally, while Uranium-238 is not normally fissile it can be fissioned with high energy neutrons. The "problem" with U-238 is that the energy range of neutrons that induce fissions only partly overlaps with the natural energy range of neutrons produced by fission reactions. Meaning that on average a given neutron emitted by a U-238 fission will cause fewer than 1 additional fissions, so it can't self-sustain a neutron induced fission chain reaction (which, I guess, is a good thing, otherwise nuclear bombs would be nearly trivial to make). However, fusion reactions generate very high energy neutrons, essentially all of which can cause fission in U-238. For this reason many thermonuclear weapons have a natural or depleted Uranium casing. Fission in the casing typically doubles the yield of the weapon compared to the yield from the primary/secondary fission/fusion reactions. All of this can be dialed to suit different desires for bomb production or yield. For example, the "Tsar Bomba" was a 100 megaton 3 stage thermonuclear warhead design, it was tested without a fissionable Uranium outer casing to avoid production of nearly 50 megatons worth of fission product fallout over the test site (which was in Russia), as a result it exploded at around 50 MT yield, almost all of which (97%) was from fusion reactions. On the other hand, you have a device like the W-88 which is an incredibly compact warhead carried on US SLBM submarines. It is a thermonuclear warhead but you could also look at it as a two stage fission-fission device with a heavily fusion boosted secondary, as most of the yield comes from fission in the secondary and the casing.

jloughry 9y ago

As others have already explained well, hydrogen in the air doesn't contribute to the explosion. But what does make a big difference is the air around the bomb---a nuclear explosion in space is way different from one in atmosphere. X-rays from the nuclear reaction heat surrounding air to many millions of degrees [1] and that's what causes (most of) the fireball you see. In space, the only matter available to make a fireball is the weapon's structure, probably only a few hundred kg, and that dissipates and cools rapidly. Nuclear-armed air intercept missiles were built in the nineteen-fifties and sixties that depended for effectiveness on being in air to generate the necessary blast effects to kill a bomber with relatively inaccurate aiming, but in space, a nuclear explosion almost needs be a contact hit to do much mechanical damage...discounting nuclear radiation effects, of course. [1] Fahrenheit, Celsius, Kelvin...it makes no difference.

computerex 9y ago
> ...discounting nuclear radiation effects, of course https://history.nasa.gov/conghand/nuclear.htm https://history.nasa.gov/conghand/nuclear.htm > Third, in the absence of the atmosphere, nuclear radiation will suffer no physical attenuation and the only degradation in intensity will arise from reduction with distance. As a result the range of significant dosages will be many times greater than is the case at sea level. With such weapons the lethal radii (from nuclear radiation) in space may be of the order of hundreds of miles.
- jloughry 9y ago
  I didn't know that. Thanks! Also: Second, thermal radiation, as usually defined, also disappears. There is no longer any air for the blast wave to heat and much higher frequency radiation is emitted from the weapon itself. So more of the energy of the bomb remains in the x-ray or gamma portion of the spectrum---penetrating radiation, hard to shield against---in addition to the longer effective range.

tw04 9y ago

If that were the case the first one would've killed us all.