Talk:History of the Teller–Ulam design

This page is

This page is lifted as-is from User:Fastfission's version of the Teller-Ulam design page, separated out because the technical page is just too long. Full credit for the work goes to Fastfission. Georgewilliamherbert 21:15, 14 August 2005 (UTC)

Three years later: I tried to give the page an overhaul. I rewrote the lead paragraph and added a lead image and caption. I also attempted to streamline the convoluted referencing methodology: at the end of the article, we had a "References" section with a {{reflist}}; a "References" section that listed the sources used by topic; and a "Notes" section that manually listed what was already in the first (reflist) "References" section. Whereas in the body, we had refs; we had plain urls in square brackets; and we had sources in parenthesis (only in one instance, with an accompanying page no.), all corresponding to the second (topical) "References" section. So, still much work to do, but an appreciable improvement nonetheless, I would hope. Incidentally, the Notes section now largely duplicates the contents of the topical References section (I removed the duplicate References section, of course), but I like the setup, so I'm incline to keep em both as is. Thx. El_C 06:20, 10 April 2008 (UTC)

Image copyright problem with Image:China H-bomb 1967.jpg

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I went through and added the rationales as required. Georgewilliamherbert (talk) 04:59, 20 May 2008 (UTC)

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United States v. The Progressive

• United States v. The Progressive

This is a fascinating legal case, anyone want to collaborate on improving the page with me? Please leave a note on my user talk page, — Cirt (talk) 19:00, 16 February 2012 (UTC)

Speculating

Thermonuclear weapon has a "highly-schematic representation" of what the inside of a warhead might look like, such as the W80 one pictured in this article. This article states that the details of the design "are military secrets known to only a handful of major nations", so it should not be surprising if that representation is not correct. It could still be broadly correct though since nuclear weapon design involves things like extremely fast conventional explosive detonation methods and materials with special properties with respect to radiation or other factors, so a simple picture of an accurate design might not provide much useful information.

This article has a citation-challenged quote of Soviet weapons designer (who won Nobel peace prize) thinking, "But how, he asked himself, can an explosion to one side be used to compress the ball of fusion fuel within 5% of symmetry?" With fission, atoms that are split were moving slowly before a particle (neutron or alpha?) interacted with the nucleus; with fusion, nuclei collide and must overcome repulsive forces though I guess maybe lithium splits into tritium or whatever. So heat and pressure are important and necessary, while with fission only pressure is desired (I guess this is because if a particle has an interactive 'width', compression means more atoms fall within this width before the particle escapes the sphere?). Triple_alpha_process#Reaction_rate_and_stellar_evolution says that "The power released by the reaction is approximately proportional to the temperature to the 40th power, and the density squared. Contrast this to the PP chain which produces energy at a rate proportional to the fourth power of temperature and directly with density." Nuclear weapons don't use either of these reactions (since they start with deuterium etc., instead of protons (¹
₁H
)).

Proton–proton chain reaction says that protons have a half-life of a billion years in the sun's core, deuterium lasts for 4 seconds, and ³
₂He
lasts for 400 years. Things involving lithium and tritium are probably on the same order as deuterium. But the point is that symmetry is very important. Anything that disrupts symmetry, and leads to lower density or temperature of parts of the fusion fuel, will cause further disruptions as the higher-density parts will start fusion but then expand into the parts of the fuel that didn't start fusion, cooling and becoming less dense in the process. This results in a lower-yield explosion, as the mass and acceleration rate of the materials surrounding the fusion fuel give a 'time limit' on how long the fusion fuel can react before the container is destroyed.

This is why I'm skeptical that thermonuclear designs have a tube surrounded by fusion fuel, as shown in the 'example' representation. Teller–Ulam_design#Basic_principle refers to "a cylinder made out of an X-ray opaque material such as uranium with the primary and secondary at either end" that "gets heated to a high temperature by the X-ray flux from the primary, then it emits more evenly spread X-rays which travel to the secondary". This article mentions "the critical role of radiation as opposed to hydrodynamic pressure". Probably, radiation not only travels faster than the physical shock wave of the primary, it's also less disruptive of the physical arrangement that makes up the secondary. So the explosion probably doesn't compress a "ball of fusion fuel [to] within 5% of symmetry", but it might compress it into a sort of plate. Then, on the sides of the fusion explosion, either more fissionable material is placed to sort of contain the edges of the plate since it doesn't have to be nearly as dense or hot as the fusion fuel in order to release energy (with its heat creating pressure on the edges of the plate even as it expands and isn't dense enough for critical chain reaction by itself), or another material that can somewhat slow the expansion of the fusion fuel without creating more radioactivity. (I'm not sure if it's accurate to say that in general, fission stages in nuclear bombs produce lots of radioactivity or if it depends on the details.)

A sphere is definitely a good shape due to its symmetry. I think a thin plate works, because unlike neutrons, the nuclei that take part in fusion can't travel through materials. One side being 'flat' seems to work because it means the energy from primary can arrive in a symmetrical fashion (after being 'reflected', so it doesn't cause the fusion fuel to spread out from the center of the primary stage?); not sure if a 'can' shape with significant thickness compared to the circle's diameter works well. It's easy to say that a flat sheet of explosive material will produce force perpendicular to the plane, thus preserving symmetry, but with a 'can' shape the corners are more significant.

So, it seems like having stages is important because it allows for mechanisms that increase the symmetry of the action on the secondary, due to the distance between the primary and the secondary. This works because the mechanism that transfers energy is X-rays, and thus isn't subject to Rayleigh–Taylor instability. 2601:600:8500:B2D9:AC6B:339:2B65:104D (talk) 20:09, 23 October 2015 (UTC)

It seems that the US is keeping secret some of the ideas for the Hohlraum used in some fusion power reactor designs. That hints that it is also related to the design of bombs, but that is as well as I know it. Other than that, it seems that the US got it right on the first bomb. Gah4 (talk) 08:19, 15 April 2021 (UTC)

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French Teller-Ulam Design

Hello, I was wondering if there has been much more information found on the French develpoment on the Teller-Ulam Design during the 1960-1970s?ANNA1120 (talk) 23:34, 24 March 2021 (UTC)

Castle Bravo and Li-7

The article mentions a few times the unexpected yield of Castle Bravo, but not why. As its article explains, it was not realized that Li-7 would contribute to the fusion reaction, and the fuel used was 50% Li-7. Now, extra fusion means more neutrons and more fission of the U-238 around the bomb, but the underlying reason is the Li-7. Gah4 (talk) 01:21, 9 January 2022 (UTC)

Debate over who should be given credit.

There should be a separate subsection dedicated to the debate of who should receive credit/ how much credit should go to who. Article is dominated by the debate. 81.134.60.119 (talk) 00:26, 27 November 2022 (UTC)