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Harmonic Generation By An Intense Laser Pulse In Neutral And Ionized Gases, X. Liu, Donald Umstadter, Eric Esarey, A. Ting
Harmonic Generation By An Intense Laser Pulse In Neutral And Ionized Gases, X. Liu, Donald Umstadter, Eric Esarey, A. Ting
Donald Umstadter Publications
Reported are the results of a harmonic generation experiment in a simple gas (hydrogen) using 1-ps, 1-pm laser pulses with a range of intensities extending from below to far above the laser ionization saturation threshold. The scaling with intensity above saturation of the third harmonic generated by a single laser-pulse in a filled gas cell is observed to not fit with a simple model that takes into consideration volume ionization effects alone. In another experiment, a pump-probe type, an upper limit on the conversion efficiency of third harmonic generation in a preformed plasma is determined. It is found to be …
Nonlinear Analysis Of Relativistic Harmonic Generation By Intenselasers In Plasmas, Eric Esarey, A. Ting, P. Sprangle, Donald Umstadter, X. Liu
Nonlinear Analysis Of Relativistic Harmonic Generation By Intenselasers In Plasmas, Eric Esarey, A. Ting, P. Sprangle, Donald Umstadter, X. Liu
Donald Umstadter Publications
A linearly polarized, ultra-intense laser field induces transverse plasma currents which are highly relativistic and nonlinear, resulting in the generation of coherent harmonic radiation in the forward direction (i.e., copropagating with the incident laser field). A nonlinear cold fluid model, valid for ultrahigh intensities, is formulated and used to analyze relativistic harmonic generation. The plasma density response is included self-consistently and is shown to significantly reduce the current driving the harmonic radiation. Phase detuning severely limits the growth of the harmonic radiation. The effects of diffraction are considered in the mildly relativistic limit. No third-harmonic signal emerges from a uniform …