PASER – particle acceleration by stimulated emission of radiation: theory, experiment, and future applications

Abstract

We review the theory and the experimental demonstration of one of the novel advanced particle acceleration techniques dubbed PASER -for particle acceleration by stimulated emission of radiation. In such an acceleration paradigm, bundles of electrons are accelerated using the same principle as in laser. A proof-of-principle experiment, conducted at the Brookhaven National Laboratory, demonstrated this novel acceleration scheme. A 45 MeV electron macrobunch was modulated by a high-power CO2 laser in a wiggler, and then injected into an excited CO2 gas mixture. The emerging microbunches reveal a 0.15% relative change in the kinetic energy in less than 40 cm long interaction region. This is the first experimental demonstration of coherent collisions of the second kind. The fundamental physics underlying the PASER paradigm is discussed via the analysis of a two-dimensional analytic model used to evaluate the energy exchange occurring as a train of electron microbunches traverses an active medium. Furthermore, advanced PASER concepts such as non-linear interaction of electrons and waves in an active medium, the occurrence of resonant absorption instability, and PASER-based optical Bragg accelerators, are considered as well. The possible impact of PASER-based accelerators on future compact medical accelerators, and on high-energy physics applications is discussed.Light-electron-atom interaction. (a) The Franck-Hertz experiment -collision of the first kind. (b) The Latyscheff-Leipunsky experiment -collision of the second kind. (c) LASER -light amplification by stimulated emission of radiation. Photons coherent multiple collisions. (d) PASER -particle acceleration by stimulated emission of radiation. Coherent collisions of the second kind. Reprinted with permission from [49].

Negative radiation pressure on gain medium structures

“…The vast majority of these studies has been focused on structures made of passive dielectric materials, whereas forces on gain media have received little attention. Gain media may be modeled by a complex permittivity with an active imaginary part; the latter may be responsible for the reversal of mechanical effects, such as the acceleration instead of deceleration of charged particles traversing through a gain medium [9,10]. The gain medium itself, however, may be subject to forces that are due to the stimulated emission of radiation.…”

Electron bunching in a Penning trap and accelerating process for CO 2 gas mixture active medium

“…Before proceeding, we make the following assumptions: (1) the transverse distribution is independent of the longitudinal distribution, and it's contribution to the energy exchange is negligible, (2) in the radial direction, the electrons are uniformly distributed in the range 0<r<R b , so the transverse filling factor 〈G[Λρ ν , Λρ μ ]〉 ν,μ can be replaced by transverse form factor…”

“…In particle acceleration by stimulated emission of radiation (PASER) [1][2][3], the energy stored in molecules or atoms is directly used to accelerate electrons. PASER does not need phase-matching or compensation for phase slippage, nor does it require a high power laser, a beam driver, or an electron gun.…”