A tapering enhanced stimulated superradiant amplification method and system which utilizes a strongly tapered undulator in reaching significant power outputs and conversion efficiencies. TESSA dramatically increases conversion/amplification efficiencies by violently (sharply) decelerating electrons and taking advantage of produced radiation to further drive interaction toward as it takes advantage of produced radiation to further drive interaction to increase overall radiation output. The system and method configures a strongly tapered undulator to operate in a new mode that is above normal input saturation levels to provide an amplified output with unexpectedly high efficiencies and power.