Kinetic description of a wiggler pumped ion-channel free electron laser

Abstract

The wiggler pumped ion-channel free electron laser (WPIC-FEL) is treated and the classes of possible single-particle electron trajectories in this configuration are discussed in the paper. A new region of orbital stability is seen in the negative mass regime. A kinetic description of WPIC-FEL is given. Vlasov-Maxwell equations are solved to get the linear gain in a tenuous-beam limit, where the beam plasma frequency is much less than the radiation frequency and the self-field effects can be ignored.

Effects of ion-channel guiding on the saturation mechanism of a single-pass free-electron laser

“…The corresponding initial axial velocity can be derived by solving the cubic equation b z 2 b w 2 +b z 2 =1Àg 2 in Àb z 2 , which results from requiring the conservation of the total energy g=(1Àb 01 2 Àb 02 2 Àb 03 2 ) À1/2 for the steady state orbits versus a w , o p 2 and g [7]. One finds…”

“…is the modified FEL parameter in the presence of the ion channel [7]. In the case of the high gain Compton regime (i.e.…”

“…Theoretical investigation of the FEL dynamics in the presence of an ion channel has been first attempted in the context of linear theory [4][5][6][7][8]. Very recently, a onedimensional nonlinear approach has been proposed [9], allowing to describe the FEL evolution from linear stage to saturation.…”

“…Very recently, a onedimensional nonlinear approach has been proposed [9], allowing to describe the FEL evolution from linear stage to saturation. In this paper we take advantage from this formulation, which is a modification of a model introduced by Freund et al [10] for the case of axial magnetic guiding, to study the effects of ion-channel guiding in the special case of the Fermi @ Elettra FEL [11].…”

Kinetic description of a wiggler-pumped ion-channel free-electron laser by applying the Einstein coefficient technique

“…A uniform axial magnetic field is often employed to collimate the relativistic electron beam in the transverse direction. Another advantage of the ion-channel guiding is that the effect of the ion channel would also be to increase both the gain and efficiency of the interaction (Jha and Kumar 1996;Mahdian and Raghavi 2006;Mahdian et al 2008;Hasanbeigi et al 2011;Su and Tang 2011;Sadegzadeh et al 2012); it also permits beam currents higher than the vacuum limit. The use of the ionchannel guiding as an effective method for enhanced focusing of an intense electron beam in a single-pass FEL was offered by Takayama and Hiramatsu years ago to improve the system performance (Takayama and Hiramatsu 1988).…”