Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!emory!att!cbnews!cbnews!military From: henry@zoo.toronto.edu (Henry Spencer) Newsgroups: sci.military Subject: Re: Thermonuclear Trigger Message-ID: <1990Dec4.002646.10188@cbnews.att.com> Date: 4 Dec 90 00:26:46 GMT References: <1990Dec3.050137.1908@cbnews.att.com> Sender: military@cbnews.att.com (William B. Thacker) Organization: U of Toronto Zoology Lines: 62 Approved: military@att.att.com From: henry@zoo.toronto.edu (Henry Spencer) >From: John Masly > Thanks to both, for explaining the jargon to me. The original > phrase that got me started was "thermonuclear weapons no longer > need 'sparkplugs' ". Obviously, they do, wheather it is called > Oralloy or U-235, or plutonium. To believe otherwise, would be > to assume that the national labs (Sandia, LLL, etc.) have found > a means to produce fusion without the flash-bang of a fission > device... No, sorry, you missed the original point entirely. The fission explosion used to compress and heat the fusion package is *not* called a "sparkplug". All current fusion bombs do need that one. The question is whether current fusion bombs need a *second* fission assembly, inside the fusion assembly, to actually ignite the fusion reaction. That's what a "sparkplug" is. It is reported that US fusion bombs used to use sparkplugs, but that modern ones do not need them. >>BTW, the Tritium (H-3) in the fusion weapons comes from the fissioning of >>Lithium-6 ... > > ... Many nuclear weapons are 'yield selectable'... > ... Since it is kind of hard to add more solid material to > an encased bomb, the only reasonable way I can see of doing > this, is to add additional (gaseous) fusionable material to the > the device at the proper time (and place) in the nuclear process. Dial-a-yield bombs are reported to function mostly by introducing varying (but small) amounts of tritium into a *fission* core. Most modern fission bombs use a small amount of fusion to "boost" the fission reaction (this should not be confused with the use of a fission explosion to ignite a much larger fusion explosion), and varying the amount of fusion apparently varies the fission yield fairly effectively. Precisely how this carries over into a variable yield in the main fusion reaction of a fusion bomb is less clear, but the obvious possibility is that less energetic heating and compression of the fusion package means less fusion yield (certainly the equivalent is said to be true for fission bombs: getting more energy into the core during the implosion process gives higher fission yield). > Also, nuclear devices receive periodic maintenance just like > every other item in the inventory, so if the half-life of H-3 > is just 12.xxx years, what would be so inconvienent about > replacing the H-3 container on a periodic basis? ... In fact, replacing the tritium in the "booster" charge is said to be a significant part of the periodic-maintenance requirement for nuclear weapons. However, this is a relatively small amount of gas. Using tritium as fusion fuel would require much larger amounts, and it would probably have to be stored as liquid. The first US fusion-bomb test reportedly used liquid deuterium and tritium, and replacement of those by more easily stored materials is said to have been the major step needed to produce a practical weapon. > what are the decay products of H-3? Isn't one of them Deuterium > (H-2)? What is it's half-life? :-) Tritium decays into helium-3, which is stable. -- "The average pointer, statistically, |Henry Spencer at U of Toronto Zoology points somewhere in X." -Hugh Redelmeier| henry@zoo.toronto.edu utzoo!henry Brought to you by Super Global Mega Corp .com