Interaction of Femtosecond Terawatt Laser Radiation with Plasmas and Materials

Tuesday, March 23, 2010 - 3:15pm - 4:30pm
Reiss 502
Dr. Antonio (Tony) Ting
Plasma Physics Division, Naval Research Lab

Intense femtosecond pulses generated from chirped pulse amplification terawatt lasers can deliver focused intensities >1020 W/cm2. A wide range of research topics, from the nonlinear interaction of intense lasers with the atmosphere to the relativistic interaction of ultra-intense lasers with plasmas, are being studied at the Plasma Physics Division of the Naval Research Laboratory. These intense laser pulses can propagate nonlinearly in the atmosphere and lead to filamentation of the laser and ionization of the air, with applications such as remote sensing and artificial lightning. Similar propagation in water can lead to breakdown and acoustic signal generation. Terahertz radiation can also be generated using appropriate nonlinear crystals. More interestingly, these laser pulses can be used to generate large amplitude plasma waves for ultra-high gradient acceleration of electrons in the Laser Wakefield Acceleration mechanism. Quasi-monoenergetic electron beams accelerated to >1 GeV have been reported in a strongly nonlinear regime where total cavitation of the plasma was inferred. Diagnostic of such “bubbles” was proposed and studied by NRL to observe the Cerenkov second-harmonic generation in the high density sheath of the plasma bubble. Recent experiments at NRL have shown evidences of such second harmonic Cerenkov radiation and its dynamics with electron acceleration.[1] Characterization of this optical radiation and electron acceleration will be presented.

Work supported by Office of Naval Research and Department of Energy

[1] M. H. Helle, D. Kaganovich, D. F. Gordon, and A. Ting, “Measurement of Electro-Optic Shock and Electron Acceleration in a Strongly Cavitated Laser Wakefield Accelerator”, submitted to Phys. Rev. Lett. (2010).

Unclassified – unlimited distribution

Host: Edward Van Keuren
Discussion Leader: Edward Van Keuren