Alarm Clock Configuration Emerges

Klaus Fuchs departed from Los Alamos on June 15, 1946, but research and development on the hydrogen bomb continued on. At the end of August 1946, Teller proposed a new bomb configuration, which he dubbed the "Alarm Clock." The scheme alternated spherical layers of fissionable materials and thermonuclear fuel (deuterium, tritium and possible their chemical compounds). Fast neutrons generated in thermonuclear reactions in the fuel layers would trigger fissions in the adjacent layers of separating materials, significantly boosting the energy release.

Diagram of the Alarm Clock or Layer Cake design
Diagram of the Alarm Clock or Layer Cake design

"Alarm Clock" would require a hugely powerful atomic initiator to trigger it. In fact, the power demand was so tremendous that the design was expected to require the generation of megaton or even multimegaton energy release, ruling out any possibility of compressing it by chemical explosives. Beginning in September of 1946, theoretical investigations of the classical Super and Alarm Clock projects were conducted in parallel programs at Los Alamos. In September 1947, Edward Teller proposed the application of a new thermonuclear fuel in the Alarm Clock: lithium-6 deuteride, which was supposed to greatly enhance the production of tritium during explosion and thereby substantially increase the thermonuclear combustion efficiency. However, due to nearly insurmountable initiation problems, work on the Alarm Clock design faded, although theoretical studies on the concept continued at Los Alamos along with work on the classical Super.

Still unbeknownst to the American team, in March 1948 in London, Fuchs provided a Soviet agent with information on the progress of the classical Super, and there were new public pronouncements in the open press during this time. Among these was an article by Edward Teller himself in the "Bulletin of the Atomic Scientists." Espionage and secrecy continued to color the nuclear arms race.

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