Emittance Preservation in an Aberration-Free Active Plasma Lens

Abstract

Active plasma lensing is a compact technology for strong focusing of charged particle beams, which has gained considerable interest for use in novel accelerator schemes. While providing kT/m focusing gradients, active plasma lenses can have aberrations caused by a radially nonuniform plasma temperature profile, leading to degradation of the beam quality. We present the first direct measurement of this aberration, consistent with theory, and show that it can be fully suppressed by changing from a light gas species (helium) to a heavier gas species (argon). Based on this result, we demonstrate emittance preservation for an electron beam focused by an argon-filled active plasma lens.

Design study for a compact laser-driven source for medical x-ray fluorescence imaging

“…Thus, separate beam optics are required to manipulate duration and focusing individually, e.g., via chirped and parabolic mirrors [37]. A discharge-capillary active plasma lens (APL) [59][60][61][62][63] allows for single-element symmetric electron bunch focusing at short focal length [60,63] while preserving the beam emittance [62].…”

“…By that, electron bunches can be focused symmetrically by a single element to short focal lengths and thus small focal waists. Here, we assume a linear radial magnetic field gradient in the capillary without temperature-related effects [61,62]. Also, fringe fields at the capillary edges play no role [63].…”

“…We propose to employ chirped and parabolic mirrors to adjust the laser properties. Active plasma lenses (APLs) [58][59][60][61][62][63] allow for electron focusing and exerting control on the focal parameters of the bunch. The TS results of APL-focusing are compared with an unfocused bunch of finite energy spread.…”

Laser-ionized, beam-driven, underdense, passive thin plasma lens

“…Plasma lenses have been primarily studied in the context of the overdense regime [19][20][21], wherein the plasma density exceeds the electron beam density and the resultant plasma response is linear or quasilinear, resulting in a nonlinear focusing response. Active plasma lenses [22][23][24] operate in this regime and utilize an applied, axial current in a discharge breakdown plasma source. The axial current produces a focusing azimuthal magnetic field that is adjusted through the operating current and plasma density of the device.…”

Modeling and diagnostics for plasma discharge capillaries

“…Experiments on laser wakefield acceleration (LWFA) [1], plasma wakefield acceleration (PWFA) [2], and plasma lensing [3][4][5][6][7] have recently undergone a great deal of development. Because of the high gradients that plasma environments can sustain, accelerator physicists have been paying increasing attention to the field of plasma acceleration, conceiving novel accelerator designs and acceleration schemes [8] with the goal to provide the best performances in terms of beam emittance [6,7,9], high energy-gain, and strong focusing [4,9]. Plasmas can sustain high gradients according to their electron plasma density.…”