Generation of a highly collimated, mono-energetic electron beam from laser-driven plasma-based acceleration

High-quality stable electron beams from laser wakefield acceleration in high density plasma

“…In the present experiment, however, a few hundred μm interaction length, combined with the high density, might have facilitated sufficient pulse evolution, eventually leading to the self-injection and acceleration in the bubble regime. We have observed quasimonoenergetic beams with lower energy ∼ 20 MeV at relatively higher plasma density of 8.5 × 10 19 cm −3 in our previous experiment using the similar laser intensity but with almost double the focal spot size [12]. In that experiment, the wakefield excitation and the electron acceleration occurred as a result of strong selfmodulation seeded by the forward Raman scattering instability [22], which is inherently susceptible to shot-to-shot fluctuations.…”

“…The laser beam was focused using an f=5 off-axis parabola, along 1.2 mm width of a rectangular supersonic helium gas jet, such that the focus was at a height of 1 mm above the nozzle orifice. The gas jet density was obtained from interferometry and it was further confirmed from the forward Raman scattering measurements [11,12]. The longitudinal profile of the gas jet was flat topped, with scale length about 100 μm at the edges.…”

Effect of chirp on self-modulation and laser wakefield electron acceleration in the regime of quasimonoenergetic electron beam generation

“…5 Â 10 19 cm À3 and the charge of the accelerated electrons was observed to increase exponentially with the plasma density. Further, generation of low divergence, quasimonoenergetic electron beam was observed for a plasma density of ' 8:5 AE 0:5 Â 10 19 cm À3 [17]. Next, the effect of chirp on self-modulation and electron acceleration for two different plasma densities, n e ' 6:5 AE 0:5 Â 10 19 cm À3 (case 1) and n e ' 8:5 AE 0:5 Â 10 19 cm À3 (case 2), was studied.…”

“…Quasimonoenergetic electron bunches have also been produced in the strongly self-modulated LWFA (SM-LWFA) regime by using longer pulses (c ) p ) and higher plasma density [16][17][18]. In this regime, a single long laser pulse with duration c ) p breaks up into multiple short pulses through forward Raman scattering (FRS) instability [19], each of which has a width of the order of the plasma wavelength p [16].…”

Generation of intense ultrashort midinfrared pulses by laser-plasma interaction in the bubble regime

“…The initial growth of Raman peaks is consistent with the fact that the pump pulse duration is longer than the plasma oscillation period. Recent experiments showed that even when the pump pulse duration is a few times larger than the plasma oscillation period, production of monoenergetic electron beams is still observed [23,24,31,32]. Therefore, the bubble regime in laser plasma interaction should not strictly be limited to the cases where the pump pulse duration is smaller than the plasma oscillation period.…”