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Does anyone know of any modern (1990's - present) computer modeling of the Orion pusher plate and its reaction/survivability to repeated plasma impacts?

Regarding the 1950s/1960s Orion Project using nuclear pulse propulsion: I see a lot of statements that "Orion would have worked. The only thing stopping us is the political will." I am skeptical of this claim.

George Dyson's book included quotes from project veterans and modern experts who pointed out that some key questions remained about basic feasibility. Specifically, could the pusher plate survive the repeated plasma impacts? To my knowledge, two key questions remain unanswered in the public domain.

The first is regarding the erosion of the pusher plate and hinged on questions of the turbulence of the plasma stagnation zone at the plate surface and its opaqueness or transparency to UV. The interviewee claimed that this could be modeled by modern nuclear bomb software, but either nobody had done the work or they couldn't talk about it.

The second question regarded spalling of the pusher plate. It's possible that the shock wave would traverse the pressure plate and blow material off of the upper side. Orion was before HESH warheads were developed; I believe its designers were unaware of this physical process. Again, modern computer codes run by experts in armor, ballistics, and metallurgy could probably nail down if the pusher plate would spall, and if so would know if there are any modern materials or construction methods that could prevent it. Again, this may be "military grade" expertise and either the work hasn't been done or can't legally be divulged.

Do any of you space experts have any substantial inputs on this?

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    $\begingroup$ HESH was designed by the British for WWII. There is no reason to suppose Orion designers more than a decade later would have been ignorant of those principles. Also, experiments were done on controlling erosion from blasts by using a thin coating of oil. $\endgroup$ – Nathan Tuggy Apr 29 '16 at 5:20
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Have a read here. 'Evidence of this obtained from nuclear tests was the foundation for further research into the feasibility of a pusher plate. It was discovered that ablation (erosion) of the surface of a pusher plate could also be reduced by coating it with graphite. Coating the launch pad in similar fashion would minimize ablation of the surface and therefore create very little fallout indeed.'

I have been studying this project for a year or so and it looks quite promising if an exception can be made from the Nuclear test treaty for a ground or space launch.

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    $\begingroup$ The pusher plate had to withstand hundreds or thousands of blasts. They planned to spray a thin coat of oil on it between pulses. The researchers acknowledged at the time that how well this would work could only be demonstrated by physical testing. Could they limit plate erosion to .0001" per blast? .001"? The hot plasma hits the oil-coated pusher plate every two seconds for hundreds or thousands of pulses. Even with the oil coating, some erosion was expected. By the mid-90's our computer simulations could probably tell you how much. $\endgroup$ – Kengineer May 1 '16 at 18:04
  • $\begingroup$ @Kengineer, they didn't bother with computer simulations. They tested things the old-fashioned way: by setting up pusher plate designs next to atom bomb tests. $\endgroup$ – Mark Aug 24 '16 at 1:10
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    $\begingroup$ Per Dyson's book, the project was cancelled before they could test with real nukes. Initially they inferred that a thin oil coating could protect steel based on the condition of shot towers and other components exposed to nuclear blasts. Then they modeled the pusher plate mathematically to the best of their ability, which in the 1960's was very limited (by modern standards). In the past ~ 25 years has anyone modeled the Orion pusher plate with a supercomputer and modern physics codes? $\endgroup$ – Kengineer May 8 '17 at 20:38
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The problem with simulating something like Orion are the ridiculous numbers and gradients involved. Nuclear explosions have a core temperature in the millions of kelvin, but this temperature rapidly drops off as you get further away (particularly as you move away from the fireball) which makes it very difficult to model. Furthermore, Orion involves plasma - again, something which is pretty tough to model.

There probably are supercomputers capable of running these types of simulations, but why bother? Orion was killed by the test ban treaty in 1963 and it will be impossible to garner the political will to launch something such as Orion, despite the huge potential benefits. Any simulation of Orion wouldn't really have a useful purpose, thus there is no point for it to be simulated on something costly to run such as a supercomputer.

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    $\begingroup$ Welcome to the Space Exploration Stack Exchange. Your answer would probably be better as a comment (you may need to build up a little reputation first). It doesn't really answer the question. Stack Exchange tries to focus on referenced answers to precise questions, not just discussion or opinion. $\endgroup$ – Steve Linton Jun 28 '18 at 16:11
  • $\begingroup$ It's probably notable that you don't need anything like a supercomputer to outdo the computing power of the early 1960's. The CDC 6600 was released in 1964 and could do about 3 million floating point operations per second (3 megaflops). For comparison, you can easily get a graphics card that can do 8 trillion floating point operations per second (Nvidia GeForce 1070 Ti) today for... not all that much money, comparatively. Better simulations don't really need a national effort, you can do better simulations than they had at the time on your phone (which can do a few thousand times better too). $\endgroup$ – Delioth Jun 28 '18 at 16:56

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