Reply to “Comment On ‘Vacuum electron acceleration by coherent dipole radiation’ ”

Wang et al. [Phys. Rev. E 65, 028501 (2002)] claim that an electron interacting in vacuum with a unipolar plane electromagnetic wave will permanently gain energy, thus circumventing the Lawson-Woodward Theorem. We demonstrate that realistic, three-dimensional unipolar impulses cannot permanently impart energy to electrons in vacuum, leaving only the idealistic, one-dimensional, plane-wave impulse as a topic for academic discussion. We also note in passing that the version of the Lawson-Woodward theorem, which they are employing, is an erroneous version that has emerged in the laser acceleration literature over the last decade, and we direct the reader to the relevant papers containing the correct version of the theorem. Finally, we show that both our work and the proposal of Wang et al. are consistent with the correct version of this theory, and that the criticism by Wang et al. is thus without merit.