@ARTICLE{Mohsenpour, author = {Mohsenpour, Taghi and Ehsani Amri, Hasan and }, title = {Self-Fields Effects on Gain in a Helical Wiggler Free Electron Laser with Ion-Channel Guiding and Axial Magnetic Field}, volume = {10}, number = {1}, abstract ={In this paper, we have investigated the effects of self-fields on gain in a helical wiggler free electron laser with axial magnetic field and ion-channel guiding. The self-electric and self-magnetic fields of a relativistic electron beam passing through a helical wiggler are analyzed. The electron trajectories and the small signal gain are derived. Numerical investigation is shown that for group I orbits, gain decrement is obtained relative to the absence of the self-fields, while for group II orbit gain enhancement is obtained. }, URL = {http://ijop.ir/article-1-238-en.html}, eprint = {http://ijop.ir/article-1-238-en.pdf}, journal = {International Journal of Optics and Photonics}, doi = {}, year = {2016} }