Self-modulated laser wakefield accelerators as x-ray sources. (17th February 2016)

• Record Type: Journal Article
• Authors: Lemos, N; Martins, J L; Tsung, F S; Shaw, J L; Marsh, K A; Albert, F; Pollock, B B; Joshi, C
• Is Part Of: Plasma physics and controlled fusion. Volume 58:Number 3(2016:Mar.)
• Publication Date: 2016-02-17
• Subjects: betatron radiation -- laser wakefield acceleration -- direct laser acceleration -- particle-in-cell codes -- laser–plasma interaction -- self-modulation instability -- Raman forward scattering; Plasma (Ionized gases) -- Periodicals; Controlled fusion -- Periodicals; 530.44
• DOI: 10.1088/0741-3335/58/3/034018
• Languages: English
• ISSNs: 0741-3335

Abstract

Abstract: The development of a directional, small-divergence, and short-duration picosecond x-ray probe beam with an energy greater than 50 keV is desirable for high energy density science experiments. We therefore explore through particle-in-cell (PIC) computer simulations the possibility of using x-rays radiated by betatron-like motion of electrons from a self-modulated laser wakefield accelerator as a possible candidate to meet this need. Two OSIRIS 2D PIC simulations with mobile ions are presented, one with a normalized vector potential a 0 = 1.5 and the other with an a 0 = 3. We find that in both cases direct laser acceleration (DLA) is an important additional acceleration mechanism in addition to the longitudinal electric field of the plasma wave. Together these mechanisms produce electrons with a continuous energy spectrum with a maximum energy of 300 MeV for a 0 = 3 case and 180 MeV in the a 0 = 1.5 case. Forward-directed x-ray radiation with a photon energy up to 100 keV was calculated for the a 0 = 3 case and up to 12 keV for the a 0 = 1.5 case. The x-ray spectrum can be fitted with a sum of two synchrotron spectra with critical photon energies of 13 and 45 keV for the a 0 of 3 and critical photon energies of 0.3 and 1.4 keV for a 0 of 1.5 in the plane of polarization of the laser. The full width at half maximum divergence angle of the x-rays was 62 × 1.9 mrad for a 0 = 3 and 77 × 3.8 mrad for a 0 = 1.5.