The atomic bomb certainly had a cursory dependence on special relativity. E = mc^2, you know.
Klystrons were used in WW2, and the beam current of a klystron scales as the beam voltage to the 3/2 power (due to space charge limits). Modern klystrons operate with relativistic electron beams, but I don't know if any of the WW2 ones did.
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The atomic bomb certainly had a cursory dependence on special relativity. E = mc^2, you know.
Klystrons were used in WW2, and the beam current of a klystron scales as the beam voltage to the 3/2 power (due to space charge limits). Modern klystrons operate with relativistic electron beams, but I don't know if any of the WW2 ones did.