Ion-channel laser

Synchrotron radiation from electron beams in plasma-focusing channels

“…The betatron motion in a focusing channel also forms the basis of the ion channel laser (ICL) [14]. In the ICL, radiation at the resonant wavelength λ = λ β /2γ 2 can feed back on the electron beam, leading to axial bunching of the beam, and coherent amplification of the radiation.…”

“…Associated with the ion channel are very strong transverse fields, on the order of several thousand Tesla per meter, that subsequently focus the body of the electron bunch. Since the initial beam radius (50 − 100 µm) is much greater than the matched beam radius (∼ 5 µm), the beam radius will undergo betatron oscillations as it propagates through the plasma [5], [14]. In the blowout regime, the radial space charge electric field [5] is E r = (em e /c 2 )k …”

“…In Ref. [14], the ICL was considered only in the limit The remainder of this article is organized as follows. Section II discusses the motion of a single electron, as well as of the radius of an electron beam, in a plasma focusing channel.…”

“…An electron residing off-axis will undergo radial betatron oscillations about the axis due to the transverse focusing force of the wakefield. As an electron undergoes betatron oscillations in a plasma focusing channel, it will emit synchrotron radiation [14], [27], [28] (see Fig. 1).…”

“…The propagation of electrons beams through plasmas is relevant to a variety of advanced accelerators [1] - [5] and novel radiation sources, such as the plasma-focused free electron laser (FEL) [6] - [10], the plasma-wiggler FEL [11], [12], the ion-ripple laser [13], and the ion-channel laser [14]. Recent experiments that explore the interaction of an intense electron bunch with a plasma include the plasma wakefield accelerator (PWFA) experiment at Argonne National Laboratory [3], the E-150 plasma lens experiment at Stanford Linear Accelerator Center (SLAC) [4], and the E-157 PWFA experiment at SLAC [5].…”