Antimatter Bombs VS Nuclear Bombs For Project Orion

[Guest]

1 hour ago, kerbiloid said:

(Silently opens "Energy conservation law". Reads. Closes.)

Then read it again. You're off by a factor of two (you need to take final mass, not initial). 

<snip>

[kerbiloid]

33 minutes ago, Dragon01 said:

Then read it again. You're off by a factor of two (you need to take final mass, not initial). 

DIY. I used the factor of two

Quote

Energy = 1*10^-3 kg * 2 (because "anti") * (3*10⁸ m/s)² ~= 1.8*10¹⁴ J.

<snip>

[Guest]

1 minute ago, kerbiloid said:

DIY. I used the factor of two

You missed another one. You took 2000T as your end mass instead of 1000T, like you should. Because it's a rocket. Which expands propellant. Antimatter rockets with a lot of antimatter to spend tend to have a mass ratio of two. If you read what I linked, you'd have figured that out.

I've provided my links. If you won't, I'm forced to conclude you're making it up. Considering abysmal results from Phalanx-Cabra shot, and the general uselessness of bomb-pumped X-ray lasers for missile defense, any "professionals" who say wouldn't have a whole lot of credibility.

For actual professional opinions, see: K. Tsipis, "Third-Generation Nuclear Weapons," SIPRI Yearbook of World Armaments and Disarmament 1985(University Press, 1985).

[kerbiloid]

23 minutes ago, Dragon01 said:

You missed another one. You took 2000T as your end mass instead of 1000T, like you should.

When you'll be reading about the energy conservation law, don't forget to repeat also the Newton's laws.
The energy will be distributed between both parts of initial mass. (Though the most part of it will be wasted as radiation, of course).

Otherwise feel free to explain with formulas how to send a ship to Pluto with a hand grenade, properly redistributing its total energy.
 

23 minutes ago, Dragon01 said:

For actual professional opinions, see: K. Tsipis, "Third-Generation Nuclear Weapons," SIPRI Yearbook of World Armaments and Disarmament 1985(University Press, 1985).

FYI, we already have the books about the 4th generation.

But your efforts should not stay unrewarded. You can sell your 1985 year books and read the 2018 ones.
<snip>
http://arxiv.org/pdf/physics/0507139

[Geonovast]

Thread temporarily locked... stand by...

---

Unlocking.  Some comments have been edited or removed.

Guys, debating the science is fine.  But accusing other members of trolling and taunting for reactions is not ok.

Let's play nice, alright?

Thank you.

[sevenperforce]

22 hours ago, mikegarrison said:

I know "trigger" is the accepted word, but it actually kind of understates it. Fusion bombs are really fission bombs that use some of the energy released by the fission to start a fusion reaction that greatly amplifies the total energy release.

Your description is closer to a boosted fission weapon. There are really several different classifications which ought to be understood:

• Pure fission gun weapon. Forms a critical mass by slamming subcritical masses together. Limited to around 15-20 kilotons; uses enriched uranium; cannot be chained or nested or used as a trigger for a larger weapon.
• Pure fission implosion weapon. Forms a critical mass by collapsing a spherical shell. Limited to around 500 kilotons; uses plutonium. Good for triggering a larger weapon.
• Boosted fission implosion weapon. The addition of a tritium-deuterium gas mixture, injected into the core of an implosion weapon, induces a small fusion reaction which enhances the fission of the primary. Most of the yield comes from fission.
• Multistage boosted fission weapon. Alternate layers of fissile and fusile material. Up to 20% of the yield comes from fusion; the rest from fission. Size-limited to about a megaton.
• Thermonuclear "hydrogen" weapon. A boosted fission implosion primary is used to produce an x-ray flux that collapses a fusion secondary around a fissile sparkplug, causing the fusion fuel to ignite. With an inert tamper, up to 97% of the yield can come from fusion.
• Multistage thermonuclear weapon. A thermonuclear hydrogen bomb can be placed inside a depleted uranium tamper that will act as a fissile tertiary, approximately doubling the yield of the bomb. You can then use this entire package as the primary for an even larger thermonuclear weapon, if you want.

 

[magnemoe]

If you have antimatter it would be better to not use bombs but an constant trust. mix the antimatter with the reaction mass in the engine, you get lots of radiation but you don't need to get fallout, this would be far more efficiently to increase ISP.  

The problem with antimatter bombs is that if one fails ship fails pretty spectacular. 
 

[sevenperforce]

43 minutes ago, magnemoe said:

If you have antimatter it would be better to not use bombs but an constant trust. mix the antimatter with the reaction mass in the engine, you get lots of radiation but you don't need to get fallout, this would be far more efficiently to increase ISP.

The only way you'd want to do pulsed antimatter Orion would be if your containment mechanism was limited in how much antimatter it could constrain. For example, if it was impossible to contain more than about a gram of antimatter in a single container, then it wouldn't make sense to trickle-feed constant-flow antimatter engines from a bunch of tiny antimatter tanks. You're better off just chucking the entire containment mechanism out the back when it is spent. Chances are that the cost of making the antimatter will be more than the cost of making the container so you're not really losing much.

Even then, I suppose it would be better (if possible) to make each antimatter unit release containment gradually so that you have more collimated thrust. It would still be a pulsed design but you would use pulsed thrust units like the black-powder BIS lunar lander, rather than pure detonations as Orion.

54 minutes ago, magnemoe said:

The problem with antimatter bombs is that if one fails ship fails pretty spectacular.

To be fair, this is also a problem with thermonuclear Orion. Only difference is that nukes don't fail passively; antimatter containment does.

[kerbiloid]

As I quoted above, it's considered that a microgram of antiprotons is enough to run fusion in D-T without a fission primer.

If a thermonuke orion:
uses penta-_{like in KSPI-E} or deca_{I insist}- borane aneutronic fusion pellets instead of the native fission nukes,
containing also some ⁶LiD for kindling,
encased into maybe uranium, maybe some other shell,
with same beryllium filler, covered with the glorious tungsten membrane (which is already almost native for everybody who is present here),
and if suppose that requires, say, 100 times more antiprotons to ignite than D-T, i.e. a milligram

then 1000 charges require 0.1 g of antihydrogen to be beamed into the pellet reaction zone behind the ship.

So, in fact, several grams onboard looks normal.

Obviously, they should be quickly and equally portioned.
So, probably the best if not the only way is to keep the antimatter as 1000 frozen micropellets containing the antihydrogen.
Or generate it in situ, but it requires moar power. Instead, it's much safer.

As we can see, the fusion fuel will be some compound of Li, B, H, D, T all-in-one. Maybe, though, Li-D-T and B-H separated (calc knows).

Edited December 17, 2019 by kerbiloid

[magnemoe]

3 hours ago, sevenperforce said:

The only way you'd want to do pulsed antimatter Orion would be if your containment mechanism was limited in how much antimatter it could constrain. For example, if it was impossible to contain more than about a gram of antimatter in a single container, then it wouldn't make sense to trickle-feed constant-flow antimatter engines from a bunch of tiny antimatter tanks. You're better off just chucking the entire containment mechanism out the back when it is spent. Chances are that the cost of making the antimatter will be more than the cost of making the container so you're not really losing much.

Even then, I suppose it would be better (if possible) to make each antimatter unit release containment gradually so that you have more collimated thrust. It would still be a pulsed design but you would use pulsed thrust units like the black-powder BIS lunar lander, rather than pure detonations as Orion.

To be fair, this is also a problem with thermonuclear Orion. Only difference is that nukes don't fail passively; antimatter containment does.

Agree, here, the problem with orion is that efficiency is low as you can not even try to contain the explosion on an small ship as in not an colony ship or moving an asteroid. 

However an failed nuke is not an major problem unless its an ground launch and the second bomb. if you lift it off the ground with an booster its less of an problem yes its some issues with timing and you need to use an smaller charge to restart the pulsing. 

[kerbiloid]

The Orion authors had studied several scenarios of a nuke failure.

Edited December 17, 2019 by kerbiloid

[Clockwork13]

As others have said, anti matter is insanely expensive.

Also there's other issues with this, such as that it would annihilate if it comes into contact with any regular matter, which makes it difficult to keep around.

[SOXBLOX]

On 12/16/2019 at 5:10 PM, jimmymcgoochie said:

Nobody has ever built an antimatter bomb, for the simple reason that actually making antimatter at all is exorbitantly expensive, requires some form of large particle collider and the antimatter that gets produced will literally turn into nothing (apart from a burst of energy) if it touches regular matter so requires lots of energy to run magnets that keep it away from all that matter. Storing it long-term is impossible with current technologies, and even if it becomes possible in the future there's no point in doing it.

If you're making a rocket engine that literally runs on nuclear explosions, radiation clearly isn't a particularly big consideration so a regular fission-fusion system is a far better bet: it's decades-old and well-proven technology that has an existing skills base with a fairly large number of people who already work with nuclear reactors/weapons/materials and the technology to make more; the raw materials are easier to get hold of (plenty of old nuclear warheads around waiting to be decommissioned!); it's far less likely to blow up in your face, as actually getting a nuclear explosion going takes some effort and a leak of the fissile material will actually make it less likely to blow up whereas antimatter will go off the moment it touches matter and so any leak at all could be catastrophic; and when you're in space, it doesn't matter that you're flying along leaving a cloud of heavy radioactive isotopes in your wake. Antimatter is hideously expensive, hideously volatile and quite frankly over-hyped.

Absolutely right! The bombs would each require an internal containment system, making them incredibly complex and bulky. And it only takes one failure...