Allow me to review at bit. As you know, in conventional, classical, atomic explosives using fission processes, neutron emission builds fairly slowly, and therefore, for achievable values of k, it is necessary to design high values of containment. Prerequisite component inertia in the dynamic process of implosion together with proper neutron “reflectors”, “initiators” and “tampers” provide both a rapid rise in the value of k and this brief but essential containment in order that a satisfactory portion of the materials may fission. Incidental to this process, again as everyone knows, thermal conditions exceed the D+T threshold. It is understood that in some thermo-nuclear designs Li6, being subject to very high neutron densities, transmutes in the fission phase to T and provides an elegant dynamic.
Neutrons, even the “fast neutrons” of the process are, compared to photons, quite slow. The gadget takes a long time to detonate, several millionths of a second, as I understand it..
In a speculative RM device the photon emission burst would, presumably, occur at the speed of light in the substance. Therefore, assuming an essentially instantaneous collapse and a very small size (a sphere perhaps < 2 cm), which would limit the significance of trigger irregularities and heterogeneous dimensions as well as structural and chemical imperfections, the necessary >5000eV might be achieved. If so, upon operation the RM device would produce a burst of gamma of very short duration, followed very quickly by a broad and more persistent spectrum of gamma, etc., as the D+T fusion occurred, followed on by a lethal neutron flux, followed by secondary thermal phenomena – “blast effect”. The key to ignition lies, therefore, in a near instantaneous release of primary gamma. In order to keep the process near symmetry, rather like the need in an implosion device, the trigger shock might well need to be applied at several points. Because the trigger event lacks neutrons, an Li 6 tactic would obviously fail, and therefore both D and T would have to be present in the quiescent device, possibly associated with Be, for example as BeH2, one of the hydrogen atoms being a D and the other a T. This would seem to preclude large devices built on the presumed phenomena and suggests that RM triggered fusion devices cannot be much beyond the 1 to 2 KT range – just as the gossip says. Because T has a short half-life and is radioactive the device would be both modestly detectable and have a definite shelf-life.
More philosophically, I note that there seems to be a resonance in historical progression. Chemical explosives predate chemical engines. The two combine in the warships and cannons of the 19th century. Atomic explosives (which are chemical- nuclear) pre-date pure atomic “engines” and the two combine in the submarines of today. The natural progression has been that various recumbent combinations of technology lead first, as we have seen, to chemical-chemical, then to chemical-fission, then to chemical-fission-fusion. It is reasonable to suspect that a “loop” or “leap” to chemical-fusion will take place. Perhaps it has.
Thanks for the opportunity and invitation to speculate.
I enjoy your fine work, good humor, and obvious joy in chemistry. Please keep going!
Best,
Wm. Yerkes
