Characteristics of multipass amplifiers

A description is given of a new method for design calculations of multipass systems. This method is based on some properties of the Frantz–Nodvik equation. The condition for optimal, from the point of view of the efficiency, operation of an amplifier is found. An analysis is made of the dependences of the efficiency, backward-wave gain, and degree of distortion of the pulse profile on certain parameters (small-signal gain, reflection coefficient of the mirrors, and number of passes) of an amplifier operating under such optimal conditions. A comparison is made with traditional single-pass systems.