Effect of polarization and focusing on laser pulse driven auto-resonant particle acceleration

Abstract

The effect of laser polarization and focusing is theoretically studied on the final energy gain of a particle in the Auto-resonant acceleration scheme using a finite duration laser pulse with Gaussian shaped temporal envelope. The exact expressions for dynamical variables viz. position, momentum, and energy are obtained by analytically solving the relativistic equation of motion describing particle dynamics in the combined field of an elliptically polarized finite duration pulse and homogeneous static axial magnetic field. From the solutions, it is shown that for a given set of laser parameters viz. intensity and pulse length along with static magnetic field, the energy gain by a positively charged particle is maximum for a right circularly polarized laser pulse. Further, a new scheme is proposed for particle acceleration by subjecting it to the combined field of a focused finite duration laser pulse and static axial magnetic field. In this scheme, the particle is initially accelerated by the focused laser field, which drives the non-resonant particle to second stage of acceleration by cyclotron Auto-resonance. The new scheme is found to be efficient over two individual schemes, i.e., auto-resonant acceleration and direct acceleration by focused laser field, as significant particle acceleration can be achieved at one order lesser values of static axial magnetic field and laser intensity.

Polarization effects in cosmic-ray acceleration by cyclotron autoresonance

“…In terms of the radiation-field phase, the initial conditions on the position translate into η 0 = −kz 0 . In developing the analytic solutions, a resonance condition is arrived at, which may be expressed by [16,25,35,36]…”

“…Here, the role that could be played in CARA by polarization of the radiation field is investigated [22][23][24][25]. Issues regarding plausibility of the classical approach, radiation loss, and the radiation-reaction effects, will all be left out as they have been discussed elsewhere [16].…”

Effect of radiation-reaction on charged particle dynamics in a focused electromagnetic wave

“…This region is associated with a monotonic decrease in the parameter . Finally in a recent work 11 , the auto-resonant scheme of charged particle acceleration has been studied in the presence of a focused light wave. The charged particle which is initially non-resonant, is accelerated by the focused pulse and brought into resonance; which is then accelerated to very high energies.…”

Radiation reaction effect on laser driven auto-resonant particle acceleration

“…couples the particle dynamics along the transverse spatial components and decoupling of the motion yields driven harmonic oscillator equations along these components [25,27]. The oscillators are driven by externally applied field of laser together with the static axial magnetic fields.…”

“…The previous studies[ [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]] on the topic have not considered the effect of radiation reaction in this scheme. The radiation reaction (or radiative friction) is a recoil force acting on the accelerating (retarding) particle as a result of emission of radiation and can in turn influence the motion of the particle.…”