It’s not as energy hungry as you might think because there’s a significant energy input due to the shockwave shedding thermal radiation and hot gas/plasma from

It’s not as energy hungry as you might think because there’s a significant energy input due to the shockwave shedding thermal radiation and hot gas/plasma from its “inside” edge. The clever thing here is controlling the inside edge of the shock front as opposed to just letting it form as it would normally do and by controlling it to shift the shock front away from the airframe to reduce drag.