Wednesday, May 11, 2016

Is anything secret anymore? - the proliferation of nuclear weapons design physics information.

Kim Jong Un's little show and tell some months ago, brought into sharp focus the extent to which knowledge of nuclear weapons design has leaked or proliferated.

Most people know about the project that John "Truck Driver" Coster-Mullen undertook. John conducted the best public domain study of the Hiroshima and Nagasaki  packages so far.

In the public domain, there is lots of literature on the design of explosive lenses, an unnecessary level of detail about Po-Be initiators,  the equation of state of Plutonium has been published (Ara Barsamian , Lawson et. al.) and you can work out exactly how to couple that knowledge together into a simulation of the Hiroshima and Nagasaki devices (DEG Barroso).

After Kim's pictures were made public, a lot of attention in the Non-Proliferation community focused on ideas of a levitated pit design. In the public discussion that followed a great deal of information (albeit unsourced and unverifiable) leaked out about the nature of levitated pit designs. A lot guesstimates of sizes and magnitudes flew around in the discussions. Wherever possible people began to bring up V. Danilenko and his patents for compression of gases (Gorwitz) and so with each guesstimate, the belief that Kim Jong Un is theoretically capable of showing a fusion yield or a secondary burn grew.

When it comes to more advanced thermonuclear weapons, Wikipedia has an entire page dedicated to the TN designs which contains table of pressures available for secondary compression from various sources. It identifies ablation pressure as the most suitable candidate for control of secondary compression.

While the detailed discussions of how precisely to control the shape of the pressure front that compresses the secondary are limited to publications about ICF experiments (a very well regulated source),  there is a very large body of open literature about Rayleigh Taylor and Rayleigh Meshkov instabilities and studying them in confined spaces and understanding how they affect dynamic compression (again - a very well regulated source of information). Most readers of that literature will find it difficult to translate between what is written in those papers and the specific context of an advanced thermonuclear explosive so I guess the information is effectively sequestered at that point.

That being said - I wonder how long it will be before the random discussions appearing on the internet about "does aerodynamics work in space"  veer into discussions about what happens when a cloud of interstellar gas hits a spaceship moving at the near-light speeds. Hint hint - physics doesn't care if the ball is moving or the gas is moving, the physics is still the same... (thanks xkcd).

With all this where it is... one is within ones' rights to ask - "So what is born secret anymore?" 

There are two question hidden here - 

a) Has enough information leaked out about a TN device that it is possible for people to design it with minimal effort?

b) How does one live in a world where this information is no longer secret?

Both of these questions need to be answered if we are reach a resolution on the feelings of unease that naturally accompany this state of affairs. 


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