Femtosecond pulse trains of polychromatic inverse Compton γ-rays from designer electron beams produced by laser-plasma acceleration in plasma channels

Abstract

International audiencePropagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate clean comb-like electron beams – sequences of synchronized, low phase-space volume bunches with controllable energy spacing [S. Y. Kalmykov et al., “Accordion Effect Revisited: Generation of Comb-Like Electron Beams in Plasma Channels,” in Advanced Accelerator Concepts: 16th Workshop, AIP Conference Proceedings; this volume]. All-optical control of the electron beam phase space structure via manipulation of the drive pulse phase (negative chirp) and parameters of the channel enables the design of a tunable, all-optical source of polychromatic pulsed γ-rays using the mechanism of inverse Compton scattering

Accordion effect revisited: Generation of comb-like electron beams in plasma channels

“…This residual background is not a deal-breaker for inverse Compton scattering (ICS) sources. Preliminary simulations of the ICS [16] of a narrow-bandwidth laser beam (λ =0.8 µm, ∆λ /λ =0.02) from the tricolor beams of Fig. 4 show that TABLE 2.…”

“…The channel radius and the pulse length are important parameters, controlling the number of spectral components in the beam, whereas their energy and energy difference can be controlled by changing the plasma length. Due to the low phase space volume, clear separation of spectral components in energy, and a minimal amount of noise, our comb-like beams can drive polychromatic ICS γ-ray sources [16]. Alternatively, by separating the comb components in a magnetic spectrometer and using beam delay lines, or selectively focusing them with highly chromatic magnetic quadrupole lenses, one can use these beams as drivers of multi-color free-electron lasers [24].…”

“…We show in this Report that the proposed all-optical manipulations of electron beam lead to controllable generation of GeV-scale energy combs of high quality, enabling a design of a miniature LPA driven by a high-repetition-rate, 10-TW-class laser, thus advancing development of all-optical γ-ray sources [16]. WAKE [17].…”

“…In particular, they enable generation of sequences of synchronized, fs-length bunches with a low phase space volume and controllable energy separation [9][10][11][12]. These comb-like beams may find a unique application as drivers of polychromatic γ-ray sources, yielding an unprecedented degree of control over the radiation spectrum [12][13][14][15][16]. This capability is rooted in the nature of the driver -a relativistically intense laser pulse.…”

Optical control of electron phase space in plasma accelerators with incoherently stacked laser pulsesa)

“…By exerting control over the dynamics responsible for multiple injection, these polychromatic (or "comb-like") beams may be deliberately produced, 19,20 optimized, and exploited for unique applications. 74 Here, we demonstrate that propagating the stack of pulses in a plasma channel leads to oscillations of the bubble size and to periodic injection. This controlled modulation of beam current on the femtosecond time scale results in the generation of background-free, comb-like beams, ideal drivers for tunable all-optical Compton c-ray sources.…”