By detuning you mean that they took a high yield device like say a 200 kt weapon and reduced it to 45 kt. Should that cause a fizzle?
I think reducing the yield of a 2-stage device is fairly easy:
(a) Simply reduce the amount of LiD in the second stage. Iyengar thinks that they used 2 kgs of LiD. You could obtain a dial-a-yield weapon by simply changing the amount of the LiD in the second stage;
(b) Another way and most likely way to reduce it would be to wrap the second stage by an inert blanket. One could change the blanket thickness and vary the yield.
I would be surprised if either strategy would lead to a fizzle. If this is the reason for a fizzle then I would have to say that BARC has been careless. It is not difficult to estimate the effect of variation of LID amount or blanket thickness on yield
There are 2 other ways that a fizzle could occur:
1. The intensity of the radiation due to the primary trigger was not sufficient to squeeze the second stage material. That would mean that the primary trigger did not work correctly. This does not seem to be highly probable since BARC has the technological understanding to build a simple A-bomb.
2. The primary trigger did generate high intensity radiation but it did not squeeze the secondary uniformly. I think this is the most likely scenario.
I agree that the fabrication of the secondary is not difficult provided you know the precise shape and size of the secondary. What is difficult is to uniformly squeeze the secondary. I know that the easiest way to arrange for a uniform squeeze is to subject the secondary to fluid like pressure. How they do it is a trade secret. I think this is the difficult step.
I suspect that the fizzle is not due to simple detuning because it is clear that BARC has not weaponised the S1 device. So the problem is more serious than a simple detuning. There is a lack of understanding on how to generate a uniform squeeze.
The 1998 Sakti tests have been extremely useful in enhancing BARC's understanding of the boosted fission device. I am sure they have been able to trouble shoot the S1 boosted trigger and get a fairly reliable although inefficient code for making a boosted fission device. BARC's boosted fission device would work but would weigh much more than say a similar device made in the US.
I don't think BARC has a good understanding of the 2-stage TN device. This is the reason why they have not weaponised it.
I think reducing the yield of a 2-stage device is fairly easy:
(a) Simply reduce the amount of LiD in the second stage. Iyengar thinks that they used 2 kgs of LiD. You could obtain a dial-a-yield weapon by simply changing the amount of the LiD in the second stage;
(b) Another way and most likely way to reduce it would be to wrap the second stage by an inert blanket. One could change the blanket thickness and vary the yield.
I would be surprised if either strategy would lead to a fizzle. If this is the reason for a fizzle then I would have to say that BARC has been careless. It is not difficult to estimate the effect of variation of LID amount or blanket thickness on yield
There are 2 other ways that a fizzle could occur:
1. The intensity of the radiation due to the primary trigger was not sufficient to squeeze the second stage material. That would mean that the primary trigger did not work correctly. This does not seem to be highly probable since BARC has the technological understanding to build a simple A-bomb.
2. The primary trigger did generate high intensity radiation but it did not squeeze the secondary uniformly. I think this is the most likely scenario.
I agree that the fabrication of the secondary is not difficult provided you know the precise shape and size of the secondary. What is difficult is to uniformly squeeze the secondary. I know that the easiest way to arrange for a uniform squeeze is to subject the secondary to fluid like pressure. How they do it is a trade secret. I think this is the difficult step.
I suspect that the fizzle is not due to simple detuning because it is clear that BARC has not weaponised the S1 device. So the problem is more serious than a simple detuning. There is a lack of understanding on how to generate a uniform squeeze.
The 1998 Sakti tests have been extremely useful in enhancing BARC's understanding of the boosted fission device. I am sure they have been able to trouble shoot the S1 boosted trigger and get a fairly reliable although inefficient code for making a boosted fission device. BARC's boosted fission device would work but would weigh much more than say a similar device made in the US.
I don't think BARC has a good understanding of the 2-stage TN device. This is the reason why they have not weaponised it.