Demonstration of High-Trapping Efficiency and Narrow Energy Spread in a Laser-Driven Accelerator

Abstract

Laser-driven electron accelerators (laser linacs) offer the potential for enabling much more economical and compact devices. However, the development of practical and efficient laser linacs requires accelerating a large ensemble of electrons together ("trapping") while keeping their energy spread small. This has never been realized before for any laser acceleration system. We present here the first demonstration of high-trapping efficiency and narrow energy spread via laser acceleration. Trapping efficiencies of up to 80% and energy spreads down to 0.36% (1 sigma) were demonstrated.

Cascaded modulator-chicane modules for optical manipulation of relativistic electron beams

“…However, the crucial feature relevant to highbrightness beams is the potential to introduce linearity in the phase space through harmonic modulation. This can lead to increases in both the obtainable bunching factor in harmonic generation schemes [29,30], and in particle capture efficiency [17]. The triple modulator/chicane setup can be used in two distinct ways to generate each of these waveform distributions.…”

“…In a sawtooth wave, the slope of the macrolinear portion approaches Àk 1 A=, for which a dispersion of B 3 ¼ =A 1 leads to enhanced bunching from that of a single-frequency modulator. With three sections, analysis shows that the maximum achievable bunching at the a ¼ 1 fundamental is $80% versus 58% for a single stage, which could improve IFEL performance [17]. Used as a seed for HGHG, such a distribution leads to marked improvement in the high-harmonic bunching factors which relaxes demands on the downstream radiator for the production of intense FIG.…”

“…Strong density modulations imposed at wavelengths much longer than the radiation wavelength produce regions of high-current that can enhance the output of self-amplified spontaneous emission (SASE) in freeelectron lasers (FELs) [12], or be used for the production of a train of phase-locked pulses in x-ray FELs [13,14]. Increasing the density modulation-or bunching factoralso leads to increased efficiency in inverse FEL (IFEL) accelerator applications [15,16], where an M-C prebuncher is used as an injector to increase the number of particles at the optimal phase of the high-power drive laser field, which accelerates the beam [17]. Laser modulators using higherorder transverse interactions have also been proposed for subfemtosecond longitudinal profile diagnostics [18], and to perform mode-up-conversion of the laser profile for the production of light with orbital angular momentum [19][20][21].…”

Charged particle acceleration by electron Bernstein wave in a plasma channel

“…The plasma wave accelerates the trapped electrons to high energies up to half GeV. Some experiments have even reported generation of mono-energetic electrons up to hundreds of energy with only 3% energy spread (Ebrahim, 1994;Rosenbluth & Liu, 1972;Salamin & Keitel, 2002;Sauerbrey, 1996;Shvets et al, 2000;Pukhov et al, 1999;Amiranoff et al, 1996;Lindberg et al, 2004;Kimura et al, 2004;Tochitsky et al, 2004;Clayton et al, 1994).…”

High-quality electron beams from a helical inverse free-electron laser accelerator

“…The BNL STELLA experiment 10 staged a microbuncher and gap-tapered, planar undulator to produce monoenergetic electron beams with energy gain of up to 9 MeV. This experiment took advantage of one of the characteristics of the IFEL output beam to be composed by a sequence of microbunches phase-locked to the drive laser frequency.…”