Ultraintense laser absorption and gamma-ray synchrotron radiation in near critical density plasmas

摘要

Ultraintense laser absorption and gamma-ray synchrotron radiation in near-critical-density (NCD) plasmas are investigated. Besides the known skin-depth emission and reinjected electron synchrotron emission in NCD plasmas, we find a new gamma-ray emission mechanism, where gamma-rays are dominantly produced by the Transversely Oscillating Electron synchrotron Emission (TOEE). In this new TOEE mechanism, electrons mainly oscillate in the transverse direction under the balance between the longitudinal laser ponderomotive force and the restoring electrostatic force. A great amount of gamma photons are emitted in the transverse direction, where the peak radiation power is enhanced by twice and the photon divergence angle is relatively decreased. The features of gamma-rays produced from this new TOEE mechanism have been identified and compared with the other two mechanisms by two-dimensional particle-in-cell simulations. Published by AIP Publishing.