Enhanced electron acceleration by a chirped tightly focused laser in vacuum in the presence of axial magnetic field
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THE EUROPEAN PHYSICAL JOURNAL D
Regular Article
Enhanced electron acceleration by a chirped tightly focused laser in vacuum in the presence of axial magnetic field Niti Kant1 , Jyoti Rajput1,2 , and Arvinder Singh2,a 1 2
Department of Physics, Lovely Professional University, G.T. Road, Phagwara, Punjab 144411, India Department of Physics, National Institute of Technology, Jalandhar, Punjab 144011, India Received 17 May 2019 / Received in final form 21 May 2020 Published online 2 July 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. The paper presents a scheme of vacuum electron acceleration due to tightly focused linearly polarized (LP) frequency chirped laser in the presence external magnetic field. The focused terawatt chirped laser pulse and the external axial magnetic field enable the electron of few MeV initial energy to attain high energy in GeV range, hence, explore the possibility of efficient electron acceleration. This can be achieved by optimizing the focused terawatt chirped laser and axial magnetic field parameters for resonance, which is realized between the electron and electric field of the tightly focused laser pulse. The frequency chirp plays a crucial role in enforcing resonance condition for longer duration and the applied magnetic field strongly enforces the electron to remain in the accelerating phase, thereby, both factors are equally imperative for accomplishing high electron energy gain in GeV. The presence of optimum axial magnetic field (∼8.5 MG) along with optimum value of linear frequency chirp for laser intensity 1.38 × 1020 W/cm2 results in electron beam with energy ∼5.78 GeV. During acceleration process, electron energy gain is highly sensitive to the initial phase of laser along with the frequency chirp and magnetic field. Electron trajectories in the influence of frequency chirp and magnetic field are also analyzed.
1 Introduction With the amelioration in laser technology, charged particles can be energized effectively by ultra-short high power lasers (∼10 TW) with intensity I > 1020 W/cm2 . With the introduction of chirp pulse amplification technique, such highly intense laser has unlocked new vistas of alluring potentials in laser-driven accelerators. In this era, the awareness in the field of laser-induced particle accelerators by researchers is rapidly growing. One of the challenges faced during laser-induced electron acceleration is to produce an electron beam with a small energy spread in vacuum [1,2]. Various studies have corroborated that electron can gain and retain noticeable energy from plane-wave laser beams by utilizing external electric and magnetic fields [3,4] and two crossed laser beams [5]. Application of suitable magnetic field robustly influences electron acceleration mechanism by strengthening the oscillations due to ponderomotive force and enforcing the electron towards higher energy [6]. Various efforts [7,8] have been made time to time by employing different polarizations of laser
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