PHASE SPACE ANALYSIS OF FREE ELECTRON LASER EFFICIENCY REDUCTION DUE TO RANDOM FIELD ERROR

Considering the random field error of the wiggler, we deduce the equation of phase motion and calculate the phase volume of interaction in a real helical wiggler. The result was compared with the case of the ideal wiggler field. We analyze how the random field error causes the efficiency of free electron laser (FEL) to reduce, and simulate the FEL efficiency reduction effect according to the mechanisms which we present in this paper. The consequence agrees excellently with the experiment.