Numerical Experiments on Free-Electron Lasers Without Inversion

The inversionless free-electron laser having a drift region consisting of two magnets is analyzed. Performing numerical simulations of electron motion inside wigglers and the drift region, we have shown that this system has a positive mean gain over the entire energy distribution of the electron beam. We study the influence of emittance and the spread of electron energies on the gain.

Figure 1

A FELWI setup.

Figure 2

Gain dependences on electron beam energy with different beam emittances. Plots (a) are obtained for FELWI; (b) for OK; (c) for FEL. Curves (1), (2), and (3) correspond to emittances ${ϵ}_{(1)}={10}^{-2}{ϵ}_0$, ${ϵ}_{(2)}={10}^{-1}{ϵ}_0$, ${ϵ}_{(3)}={ϵ}_0$ correspondingly, where ${ϵ}_0=2\pi \times {10}^{-6}\mathrm{m}\mathrm{r}\mathrm{a}\mathrm{d}$ is the emittance of the electron beam available at the Synchrotron Light Source Accelerator in Armenia [17].

Figure 3

Gain dependences on electron beam energy (a) for the drift region given by Eq. (10) and (b) for the drift region given by Eq. (11).

Figure 4

Gain dependence of FELWI and OK on electron current; emittance is $2\pi \times {10}^{-6}\mathrm{m}\mathrm{r}\mathrm{a}\mathrm{d}$.