|Plasma Physics Seminar ( Phys 769)|
| Prof. Tom Antonsen, IREAP, University of
Ultra-Intense Laser Pulse Interaction with Gases, Cluster Gases and Structured Plasmas*
Interest in the study of the propagation of intense optical pulses in plasma and in gas has been stimulated by the development of lasers capable of producing ultra-intense, ultra-short pulses. With these lasers a variety of novel laser matter interaction phenomena have been investigated including: self-focusing harmonic generation, ionization induced blue shifting, refraction, pulse shortening, and coherent scattering, plasma wave generation and Raman instability. The applications of these pulses are extensive and include plasma based particle accelerators, x-ray lasers, and soft x-ray generation for lithography and microscopy. A common theme in laser-plasma applications is the need to confine or guide the radiation for a distance greater than a Rayleigh length to enhance its interaction with the medium. Such guiding can be realized either through the process of self-focusing or through the use of preformed channels. However, guiding of this type constrains the guided radiation to have particular dispersive qualities. Specifically, the phase velocity along the axis of propagation is super-luminal, and the group velocity is sub-luminal. This leads to consideration of corrugated, or periodic, plasma structures that have more versatile dispersive properties. Corrugated channels can form spontaneously under the right conditions of plasma density and incident laser pulse angle. However, recently it has been shown that channels with prescribed period (1mm - ~ 35 microns) can be formed under a variety of controlled conditions. This opens a number of interesting possibilities including the direct acceleration of particles, phase matching of nonlinearly generated harmonics, and the generation of intense short pulses of THz radiation by laser pulses or electron beams.
* In collaboration with H. Milchberg, J. Cooley, A. Gupta, T. Taguchi, J. Palastro, Z. Bian, J-Z Wu, K-Y Kim, I. Alexeev, B. Layer, A. Yorke, V Kumarappan, and Supported by DoE and NSF
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