A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear diff...A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the FEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.展开更多
The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron tr...The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron trajectories is performed by solving the equations of motion. Our results show that the presence of a corrugated channel shifts the resonance frequency to smaller values of ion channel frequency. The sixth-order dispersion equation describing the coupling between the electrostatic beam mode and the electromagnetic mode has also been derived. The dispersion relation characteristic is analyzed in detail by numerical solution. Results show that the growth rate of instability in the presence of corrugated ion channels can be greatly enhanced relative to the case of an uniform ion channel.展开更多
The linear theory of free-electron laser (FEL) is established by means of the spacecharge wave theory. Equations for space-charge waves in FEL with magnetostatic wiggler have been derived and solved. The space-charge ...The linear theory of free-electron laser (FEL) is established by means of the spacecharge wave theory. Equations for space-charge waves in FEL with magnetostatic wiggler have been derived and solved. The space-charge density waves and the current waves have been obtained, and the differences between these waves and the conventional space-charge waves are discussed in detail. Using these space-charge waves, the dispersion equations of FEL have been derived, and some special cases are analyzed. A new concept and suggestion are presented.展开更多
文摘A three-dimensional simulation of a steady-state amplifier model of a long-wavelength free-electron laser （FEL） with realizable helical wiggler and ion-channel guiding is presented. The set of coupled nonlinear differential equations for electron orbits and fields of TE 11 mode in a cylindrical waveguide are solved numerically by the Runge–Kutta algorithm with averages calculated by the Gaussian quadrature technique. Self-fields and space-charge effects are neglected, and the electron beam is assumed to be cold and slippage is ignored. The parameters correspond to the Compton regime. Evolution of the radiation power and growth rate along the wiggler is studied. Ion-channel density is chosen to obtain optimum efficiency. Simulations are preformed for the FEL operating in the neighborhood of 35 GHz and 16.5 GHz for the electron beam energies of 250 keV and 400 keV, respectively. The result of the saturated efficiency was found to be in good agreement with the simple estimation based on the phase-trapping model.
文摘The effects of corrugated ion channels on electron trajectories and spatial growth rate for a free-electron laser with a one-dimensional helical wiggler have been investigated. Analysis of the steady-state electron trajectories is performed by solving the equations of motion. Our results show that the presence of a corrugated channel shifts the resonance frequency to smaller values of ion channel frequency. The sixth-order dispersion equation describing the coupling between the electrostatic beam mode and the electromagnetic mode has also been derived. The dispersion relation characteristic is analyzed in detail by numerical solution. Results show that the growth rate of instability in the presence of corrugated ion channels can be greatly enhanced relative to the case of an uniform ion channel.
文摘The linear theory of free-electron laser (FEL) is established by means of the spacecharge wave theory. Equations for space-charge waves in FEL with magnetostatic wiggler have been derived and solved. The space-charge density waves and the current waves have been obtained, and the differences between these waves and the conventional space-charge waves are discussed in detail. Using these space-charge waves, the dispersion equations of FEL have been derived, and some special cases are analyzed. A new concept and suggestion are presented.
