Songho M. Gim
Halla Technische Institut
We considered the dependence of free electron laser gain on the effective electron masses of the intense electron beam. In case of the extreme high electron density limit the formular is derived using standard many body perturbation expansions, however, for the inter electron distance around the Bhor radius or larger than that, the perturbation approach is no longer valid. The stationary phase approximation based on functionary integral methods will still not be applicable for the evaluation of the gain in this range. Hence we used stochastic numerical approximation by functional integral techniques in order to calculate the final formular of the photon amplification factor, showed this to be in agreement in the high density limit with those results obtained from perturbation methods.
