The earth is metric (and flat), so it receives about 1000watts per square meter on the surface. The US area is about 10^13 square meters, requiring 10^16 watts from space. That would take at least 100 grams of raw matter worth of energy per second (half antimatter, half normal), and classic hydrogen fusion transforms 0.7% of the hydrogen mass into energy. It'd need to burn around 14kg of pure deuterium fuel every second, or over 50 tons per hour (even more if it was packaged as heavy water), to maintain that scale of energy output, and that's assuming a pretty world where nothing goes wrong!
Or in another scale, it's at least 3 Tsar Bombas per minute.
Surely there must be an easier way of creating apocalyptic levels of energy.