RDS-6s

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RDS-6s (Russian: РДС-6с; CIA designation: JOE 4) was the first Soviet test of a boosted fission weapon that occurred on August 12, 1953, that detonated with an energy equivalent to 400 kilotons of TNT. RDS-6 utilized a scheme in which fission and fusion fuel (lithium-6 deuteride) were "layered", a design known as the Sloika (Russian: Слойка, named after a type of layered puff pastry) or the so-called layer cake design, model in the Soviet Union. A ten-fold increase in explosive power was achieved by a combination of fusion and fission, yet it was still 26 times less powerful than the Ivy Mike device tested by the US in 1952. A similar design was earlier theorized by Edward Teller, but never tested by the US, as the "Alarm Clock".

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