Vacuum amplification of the high-frequency electromagnetic radiation
  When an electrically charged source is capable of both emitting the electromagnetic waves and creating charged particles from the vacuum, its radiation gets so much amplified that only the backreaction of the vacuum makes it finite. The released energy and charge are calculated in the high-frequency approximation. The technique of expectation values is advanced and employed. 
G. A. Vilkovisky (Lebedev Institute)