| Paper |
Title |
Page |
| MOPPH016 |
Mode Couplings in a Raman Free-Electron-Laser with Ion-Channel Guiding
|
75 |
| |
- B. Maraghechi, B. Maraghechi
IPM, Tehran
- T. Mohsenpour
AUT, Tehran
|
|
| |
The free-electron laser (FEL) theory in the collective or Raman regime relies on the unstable coupling between the radiation and the negative-energy space-charge wave. Due to the high density and low energy of electron beam a focusing mechanism like an axial magnetic field is usually required to guide the beam. We have shown in our previous study that, in addition to the above coupling that constitutes the regular FEL resonance, there are other unstable coupled-mode structures in the group II orbits. In the present analysis we are studying the mode-couplings when the electron beam is guided by an ion-channel. Using fluid model, a general dispersion relation of a FEL with a one-dimensional helical wiggler and an ion-channel guiding is derived. A numerical analysis of the general dispersion relation will be used to study interactions among all possible waves. In group II orbits, with relatively large wiggler induced velocities, new couplings between the negative and positive-energy space-charge waves as well as between the right and left circularly polarized electromagnetic waves are expected to be found. These instabilities are distinct from the usual FEL resonance.
|
|
| MOPPH016 |
Mode Couplings in a Raman Free-Electron-Laser with Ion-Channel Guiding
|
75 |
| |
- B. Maraghechi, B. Maraghechi
IPM, Tehran
- T. Mohsenpour
AUT, Tehran
|
|
| |
The free-electron laser (FEL) theory in the collective or Raman regime relies on the unstable coupling between the radiation and the negative-energy space-charge wave. Due to the high density and low energy of electron beam a focusing mechanism like an axial magnetic field is usually required to guide the beam. We have shown in our previous study that, in addition to the above coupling that constitutes the regular FEL resonance, there are other unstable coupled-mode structures in the group II orbits. In the present analysis we are studying the mode-couplings when the electron beam is guided by an ion-channel. Using fluid model, a general dispersion relation of a FEL with a one-dimensional helical wiggler and an ion-channel guiding is derived. A numerical analysis of the general dispersion relation will be used to study interactions among all possible waves. In group II orbits, with relatively large wiggler induced velocities, new couplings between the negative and positive-energy space-charge waves as well as between the right and left circularly polarized electromagnetic waves are expected to be found. These instabilities are distinct from the usual FEL resonance.
|
|