Beam manipulation and acceleration with Dielectric-Lined Waveguides

Abstract

The development of next-generation TeV+ electron accelerators will require either immense footprints based on conventional acceleraton techniques or the development of new higher-gradient acceleration methods. One possible alternative is beam-driven acceleration in a high-impedance medium such as a dielectric-lined-waveguide (DLW), where a highcharge bunch passes through a DLW and can excite gradients on the order of GV/m. An important characteristic of this acceleration class is the transformer ratio which characterizes the energy transfer of the scheme. This dissertation discusses alternative methods to improve the transformer ratio for beam-driven acceleration and also considers the use of DLWs for beam manipulation at low energy.

Drive beam sources and longitudinal shaping techniques

“…As shown in Fig. 7(c), comparison of the bunch at z=50 cm is in good agreement with the ideal current profile; see [63,64] for details. Further studies and optimizations would be required to develop a usable bunch after e.g.…”

“…Recent work on longitudinal shaping approaches utilize more complex methods including spatial light modulators, dispersive optics, and feedback mechanisms [65]. The sharp edges of the desired pulses are also practically limited by bandwidth and diffraction, see [63,64] for further discussion. Recent demonstrations have also shown the usefulness of this scheme in an L-band photoinjector, leading to an observed transformer ratio of 4.6 in a plasma channel [66].…”

“…Evolution of the electron-bunch current (a) and longitudinal phase space (b) along the beamline at 20 (red), 60 (green), and 100 cm (blue) from the photocathode surface and (c) comparison of the current profile numerically simulated at s = 50 cm (red trace) with a fit to equation Eq. 3.15 (blue points)[64]. The head of the bunch is at large values of z.…”

Drive beam sources and longitudinal shaping techniques for beam driven accelerators

“…Alternative mathematically smooth current profiles have been proposed more recently [17], and are less prone to space charge forces. [79]. The head of the bunch is at large values of 𝑧. Reproduced from [17].…”

Electron Beam Shaping and Its Applications

“…The lower emittance in the latter type of beams corresponds to below-thermal emittance of the photoinjector and can pave the way for multiple future experiments at FAST. Such experiments include dielectric laser acceleration [122], phase-space manipulation and acceleration in dielectric lined waveguides [123,117,124], plasma wakefield acceleration [125,126], microundulator radiation [49]. Low emittance flat beams could also serve as a probe for highorder mode auxiliary couplers studies in the ILC-type cryomodule.…”