daemon@ucbvax.UUCP (08/03/84)
From @MIT-MC:JLarson.PA@Xerox.ARPA Fri Aug 3 04:20:49 1984 Arms-Discussion Digest Volume 2 : Issue 50 Today's Topics: Nuclear winter book, article BMD and shaped nuclear charges X-ray lasers ---------------------------------------------------------------------- Date: 29 Jul 1984 2154-PDT From: CAULKINS@USC-ECL.ARPA Subject: nuclear winter book, article To: arms-d@MIT-MC There are two new publications on Nuclear Winter - the first is the book "The Cold And The Dark, The World After Nuclear War" by Paul Ehrlich, Carl Sagan, Donald Kennedy, and Walter O. Roberts. It is published by W.W. Norton & Co, and has a 1984 copyright. The book's table of contents is as follows: The Atmospheric and Climatic Consequences of Nuclear War (Carl Sagan) 1 The Bilogical Consequences of Nuclear War (Paul Ehrlich) 41 Panel on Atmospheric and Climatic Consequences 73 Panel on Biological Consequnces 109 The Moscow Link: A Dialogue between U.S. and Soviet Scientists 131 With Appendices (including the full text of the 23 December 83 Science article), Notes, Index, etc. the whole book comes to 229 pages. It makes for grim reading, but obligatory for anyone who wants to be informed about the peril posed to our species be the unrestrained use of nuclear explosives. The second is "The Climatic Effects of Nuclear War", the lead article in the August 84 issue of Scientific American (Vol 251, No 2, P 33) by the TTAPS scientists - Turco, Toon, Ackerman, Pollack, and Sagan. Essentially the same material as in the TTAPS Science paper of December 83, plus some new stuff about possible effects on global convective Hadley cell air circulation. A less technical treatment of the subject, aided by Scientific American's excellent graphics. As the real meaning of nuclear winter effects sinks in, the implications for policy changes in nuclear weapons use doctrines become clear. Badly misguided policies like Weinberger's doctrine of 'decapitation' (as advocated in "Defense Guidance 1984-1988") are shown to be wrong in that they lead to uncoordinated, open-ended nuclear exchanges certain to exceed the nuclear winter threshold. The whole series of first-strike, second-strike scenarios used as the basis for much of US nuclear weapons use doctrine are wrong, because most present first strike scenarios invoke nuclear winter for attacker and victim alike, even if there is no second strike. So far, unfortunately, there is no sign of these use doctrine changes on the part of the US or the USSR. ------- ------------------------------ Date: 30 Jul 1984 6:15-PDT From: dietz%USC-CSE@ECLA To: arms-d@MIT-MC.ARPA Subject: BMD and shaped nuclear charges Here's an idea for BMD using advanced nuclear warheads that sounds more feasible than X-ray lasers. The idea is to use shaped charges. Conventional shaped charges are used in antitank weapons. The consist of a conical shell of dense metal coated (on the outside) by a layer of chemical explosive. When the explosive is detonated the metal is liquified and imploded, and when the compression reaches the cone's axis a very high velocity (20 km/sec) jet of molten metal shoots out the base of the cone. This jet can penetrate a considerable thickness of armor. How would one design a nuclear shaped charge? One cannot mold nuclear weapons into arbitrary shapes as with chemical explosives. Instead, one would use the X-rays from a nuclear device to heat & explode a layer of matter around the conical metal shell. This scheme looks promising. A 10 KT nuclear device yields some 4x10^13 joules of energy. Assuming 10% of this goes into propelling the jet, and the jet has a mass of 50 kg, one gets a jet velocity of 400 km/sec. When the jet has dispersed to a diameter of 1 km the energy flux is still 5 megajoules per square meter (a megajoule = about a stick of dynamite). Critical issues are jet dispersion (1% is about the maximum tolerable; 0.1% would be better), efficiency of energy transfer to the jet, and weapon mass. dietz@usc-ecla ------------------------------ Date: 2 Aug 1984 13:35-PDT From: dietz%USC-CSE@ECLA To: arms-d@MIT-MC.ARPA Subject: X-ray lasers The July 19 issue of Nature has an article containing a detailed analysis of nuclear-pumped X-ray lasers. Summary: (1) Nuclear pumped lasers are probably photoionization lasers. This class of lasers achieves a population inversion in the lasing material from the selective ejection of inner shell electrons by high energy photons. In the case of the 14.2 angstrom X-ray laser reported in Aviation Week, the lasing material was probably zinc, using the n=5 to n=3 transition. (Thermal X-rays from a nuclear fireball at 10^8 deg.K have an average wavelength of 1.3 angstroms, or roughly 10 KeV.) (2) The laser cannot use mirrors. It uses single-pass amplification (amplified spontaneous emission). The output of the laser is a superposition of pulses arising from the amplification of spontaneously emitted photons approximately aligned with the axis of the laser rod. (3) For a 14 angstrom laser with 2 meter long lasing rods, beam divergence is at least 2.92 x 10^-5 radians, so at a distance of 2000 km the beam is at least 60 m across. This is a physical limit due to diffraction effects; actual divergence will probably be higher. (4) As a result, a 50 rod weapon capable of destroying hardened Soviet boosters (boosters that need a fluence of at least 2x10^4 J/cm^2 to be destroyed) would need a nuclear explosive of at least 370 KT if the lasers are 10% efficient, and 3.7 MT if the lasers are only 1% efficient (which is more likely). Elsewhere, I've read that Hans Bethe has claimed an effective X-ray laser will need nuclear pumping charges of at least a megaton. ------------------------------ [End of ARMS-D Digest]