Tuesday, March 29, 2016

The DPRK device and what Kim wants us to believe

I note that the size of Kim Jong Un's displays is dropping.

This is a bit of a lull in the situation, so it may be a good time to think about what Kim Jong Un wants the world to believe he has.

From the photos, it is clear that

1) The size of the package appears to be around 30-35 inches. 

2) From an analysis of the wiring and the peculiar choice of Archimedian solid used we can surmise ~ 168 detonators. 

3) There is a triangular bracket on the top of the package. This could be a place to anchor the package to the support frame. 

One could draw the following conclusions from the image.

The smaller size suggests they are using something more advanced and light weight by way of explosive lenses. It is likely that they have chosen a vibration insensitive explosive like the PAX and TATB variants in vogue for the last three decades. 

The number of lens elements is larger than other designs, given the trade-off between spherical nature of the compression wave and electronic simplicity - one naturally wonders why they are willing to take such risks. One possibility is that they are fissile material limited  and are desperate to boost conversion efficiency. Another possibility are desperate to get the compression right. 

Getting the compression right is the biggest problem in this line of work. All the other stuff about equations of state and high purity metals  is all good and fine, but the real pain in the rear is making sure that you get isotropic compression. When something fizzles, the first suspect is a RT or RM instability or a rarefaction that caused mixing or decompression you didn't want to have happen. So everyone spends a great deal of time trying to nail down how the shockwave bifurcated. I really don't know what if any meaningful progress has been made on getting to actionable information on this.  People write all manner of papers on these topics, and I find them to be all interesting but I don't know what if anything is truly predictive (Hint Hint... Good Job NNSA!!).

The asymmetry of the mounting bracket is quite intriguing, It may also be a portal to place a neutron generator or a boosting gas assembly.  

There is a discussion on Arms Control Wonk about how the design is likely a levitated core design. It is difficult to conclude that from the photos Kim has released so far. Given the history of collaboration between Pakistani and DPRK nuclear weapons  efforts, it is likely that the drawings of a levitated pit design that surfaced some years ago in a Pakistani context were shared with DPRK.

That latter part is a very big statement to make. I don't know that there is any solid proof of that.

Again - proving ownership of the design paperwork does not translate into an actual demonstration at yield of a physics package. 

This is the point at which I am going to speak openly to Kim Jong Un. 

Dear Kim Jong Un, 

I don't think you will get the international recognition you seek by this kind of behavior. If you continue down this path, you will put everything your ancestors have worked for and the lives of millions of Koreans at risk and nothing will come out of it for you.

You can never fill your father or grand father's shoes in the exact same way as history cannot be made to repeat itself.  If you play these games of brinkmanship - the only thing that will happen is an accident and your own people will hold you to account for that.  

After all the trouble you have been going to show your countrymen how exactly you are directing the efforts of experts in the field and how much smarter you are then them, you will not be able to deflect the blame for that failure. There is no Uncle No. 3 that can be fed to the dogs if something goes wrong. 

A more rational approach is to follow a Raul Castro model and seek reconciliation. There is much more to be gained by signing the NPT and re-entering the community of nations as an equal partner in peace. 

Best Regards


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