Radiation reaction-dominated regime of wakefield acceleration

Abstract

We study electron acceleration in a plasma wakefield under the influence of the radiation-reaction force caused by the transverse betatron oscillations of the electron in the wakefield. Both the classical and the strong quantum-electrodynamic (QED) limits of the continuous radiation reaction are considered. For the constant accelerating force, we show that the amplitude of the oscillations of the QED parameter χ in the radiation-dominated regime reaches an equilibrium value determined only by the magnitude of the accelerating field, while the averaged over betatron oscillations radiation reaction force saturates at a value smaller than the accelerating force and thus is incapable of stopping acceleration. We find the parameters of the electron bunch and the plasma accelerator for which reaching such a regime is possible. We also study effects of the dephasing and the corresponding change of the accelerating force over the course of acceleration and conclude that the radiation-dominated regime is realized both in cases of single-stage acceleration with slow dephasing (usually corresponding to bunch-driven plasma accelerators) and multi-stage acceleration with fast dephasing (corresponding to the use of laser-driven accelerators).

Modeling of three-dimensional betatron oscillation and radiation reaction in plasma accelerators

“…As it has been discussed in Ref. [22] and [23], this classical RR model is valid as long as rγr e /2α 1, where α is the fine structure constant.…”

“…The BO in a plasma accelerator is another good case for such long interaction time. The radiation leads to the energy loss of electrons and in return affects the energy-dependent betatron frequency, as well as the other beam properties, such as the energy spread and emittance [16][17][18][19][20][21][22][23].…”