Supra-bubble regime for laser acceleration of cold electron beams in tenuous plasma

Abstract

Relativistic electrons can be accelerated by an ultraintense laser pulse in the "supra-bubble" regime, that is, in the blow-out regime ahead of the plasma bubble (as opposed to the conventional method, when particles remain inside the bubble). The acceleration is caused by the ponderomotive force of the pulse, via the so-called snow-plow mechanism. The maximum energy gain, ∆γ ∼ γga, is attained when the particle Lorentz factor γ is initially about γg/a, where γg is the pulse group speed Lorentz factor, and a is the laser parameter, proportional to the laser field amplitude. The scheme operates at a γg, yielding ∆γ of up to that via wakefield acceleration for the same plasma and laser parameters, ∆γ ∼ γ 2 g . The interaction length is shorter than that for the wakefield mechanism but grows with the particle energy, hindering acceleration in multiple stages.

Laser induced electron acceleration in an ion-channel guiding

“…4(a), the maximum net energy gained by electron occurs at a specific value of electron initial energy (i.e., c 0 ¼ 5:79). This result is in agreement with the result obtained recently by Geyko et al 44 Also as Fig. 4(b) shows, the maximum net energy gained by electron occurs at specific values of initial position of pulse peak (e.g., z 0 ¼ À10).…”

A critical analysis of the ‘ponderomotive snowplow’ concept in direct laser acceleration of electrons

“…Independently of Sazegari, Mendonca et al proposed nearly the same concept around the same time [21]. The idea has also appeared in the work of Geyko and coworkers [22,23]. Discussion of this, and similar ideas, can be found in [24].…”

Electron Acceleration in Wakefield and Supra-Bubble Regimes by Ultraintense Laser with Asymmetric Pulse

“…We consider a test electron with mass m and charge −e interacting with an intense laser pulse, the electron Hamiltonian is given as [12] H(x, t, P ) = c m 2 c 2 + P 2 + [P ⊥ + (e/c)A ⊥ ] 2 −eϕ , (1) where P and P ⊥ are the longitudinal and transverse components of the generalized momentum, A ⊥ is the vectorpotential of the laser pulse, ϕ is the potential of the wakefield, c is speed of light in vacuum. Assuming that the spatial scale of the laser envelope L = r p + l p (where r p is the rising length and l p is the falling length of asymmetric laser pulse) is sufficiently small compared to the plasma wavelength λ p , a linear plasma dispersion relation…”

“…The function δ 1 depends on laser polarization, and for the case of cold electrons (P ⊥ = 0) considered below, one has δ = 0 for circular polarization, and δ 2 < 0.168 for linear polarization. [12] It is noted that δ can significantly affect the dynamics of hot electrons. [13] For simplicity we ignore it because we just discuss problem in this paper for the cold electron and circular polarized laser pulses, thus, the Hamiltonian is reduced to…”