Effects of electron energy spread on selfexcitation of freeelectron lasers
Abstract
The performance parameters of freeelectron lasers when the particle parameters differ widely and there is a kinetic stage of interaction are analyzed. Expressions are given for the energy transfer efficiency in freeelectron lasers from a monoenergetic electron beam to the laser wave in the smallsignal approximation assuming a fixed rf field structure, as well as for the initial current in a freeelectron laser with a highQ resonator. The contributions to the laser wave energy from electron bunches having different velocities are summed, assuming a Gaussian spread, and an expression is derived which is then integrated and numerically evaluated. It is found that the particle energy spread does not seriously constrain the length, but that starting at a certain reduced length the rate of dropoff of the initial current is greatly reduced. The maximum length and smallest possible laser current are determined by the minimum acceptable efficiency.
 Publication:

Zhurnal Tekhnicheskoi Fiziki
 Pub Date:
 October 1982
 Bibcode:
 1982ZhTFi..52.2013R
 Keywords:

 Electron Energy;
 Free Electron Lasers;
 Self Excitation;
 Energy Transfer;
 Hydrodynamics;
 Landau Damping;
 Lasers and Masers