Friday, September 09, 2016

Low hanging fruit on the nuclear design side for the North Koreans

When you are rushing a nuclear weapons development program, you will be drawn towards the low hanging fruit - i.e. the low risk stuff.

The public at large is completely uneducated about the details of nuclear design, so even if they look up from their I-phones they won't be able to get that you are putting on a show and the whole thing will be an easy political sell.

The DPRK scientists are very diligent so they will go after all the low hanging fruit first before they jump at major improvements in yield. Generally speaking the big gains usually come from advances on hard material science issues. DPRK doesn't have a very big base of such efforts locally and it could synergise with a place with a bigger base like Pakistan or Iran, but that will come with its own political cost and sovereignty tradeoffs. So the DPRK scientists will seek out as many low hanging fruit as possible.

With that in mind here is a short list of the low hanging fruit.

1) "Slowly increasing yield" - It is important to note that no one outside your team knows exactly what yield you are aiming for, and no amount outside detective work can really tell anyone what you achieved yield was. Every estimate will come with error bars and no one has a flawless system of assigning error bars. As long as you can show a steady or steadily rising mb value at a seismic station, you can basically claim whatever base yield you want and satisfy local political forces. 

2) "Boosting experiments" - Using the heat from a fission reaction to light a small fusion reaction which increases the efficiency of the fission reaction is a relatively simple thing to do. If you just try to increase the combined efficiency of the fission and fusion  and avoid getting drawn into a struggle on high fusion yields, you can basically remain an arena of visible success. 

3) "Warhead development" - This is an infinite area of activities which can involve small incremental changes to the electronics design. The core problem is that the explosive lens detonators need to be fabricated and supplied with enough current. This is usually done via a big-ass capacitor which can send a massive current spike with no transmission line delay. Once you have sorted that out - you need to show the ability to reduce the weight on your batteries. Again this is a much smaller hill to climb than actually developing a warhead design that survives the rigors of its journey on a missile. No one is going to ask you - "does that work in a real warhead" because only you can tell people what a real warhead is. 

4) "Basic explosive lens design" - It is not terribly hard to come up with an explosive lens design and get it to compress a ball of Plutonium. There is a trade-off analysis the goes into determining whether you want to make a more aberration free lens with more elements or you want to make a more reliable lens with fewer elements. You can try out both designs and make claims about which is better. Again - no one will look at the details - people will stick to the highlights. No one will ask you if the explosive lens you have is too heavy or ages poorly to survive contact with the use-case. 

5) "Heat shields" - This is a particularly easy one. Beg/borrow/steal some reinforced carbon composite from the market and show everyone that you can make a conical shape with it. Add a layer of PDMS on top and show that you understand the idea behind ablative shields. No one will ask you whether the actual weight of the heat shield you make with that specific level of thermal transport is actually enough to keep your physics package from being messed up. You should be able to showcase a few tests - have some guy touch the other side of a panel while you go at the opposite side with a blow-torch and everyone will say OMG - you totally have a heat shield.

6) "Launches without terminal stage images" - Launch a rocket, have a bunch of generals and politicians stand in front of the launch vehicle and show a video of something climbing into the sky. No one will ask you - "so did you see where it landed?". A astonishingly small fraction of the people will get that the answer to that question is *no* because you had no idea where to point the camera. The red flag for this is when people say - "So and so - successfully launched a missile and it fell into the blah-blah sea".

I am not knocking anything the DPRK scientists are doing - I fully understand they are doing what they can to get by but the rest of the world needs to understand what is really going on and not get too freaked out by what they are seeing and hearing.

I am definitely in Jeffrey's camp. I think Jeffrey is essentially correct that one needs to sit down with Kim Jong Un and have a heart to heart talk. I also agree that THAAD is not useful in this context and the costs will likely outweigh any benefits.

I don't know what Jeffrey wants to say to him, but someone needs to talk to him and tell him that he isn't going to make Taewonsu this way - the only way you earn that coat lapel is by fighting in an actual shooting war. It seems very silly to start a shooting war just to get a lapel and pin on your coat!

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