Terahertz Pulse Generation in Underdense Relativistic Plasmas: From Photoionization-Induced Radiation to Coherent Transition Radiation

Terahertz to far-infrared emission by two-color, ultrashort optical pulses interacting with underdense helium gases at ultrahigh intensities (>10^{19}  W/cm^{2}) is investigated by means of 3D particle-in-cell simulations. The terahertz field is shown to be produced by two mechanisms occurring se...

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Bibliographic Details
Published in:Physical review letters 2018-04, Vol.120 (14), p.144801-144801, Article 144801
Main Authors: Déchard, J, Debayle, A, Davoine, X, Gremillet, L, Bergé, L
Format: Article
Language:English
Subjects:
Accelerator Physics
Bursting strength
Color
Computer simulation
Far infrared radiation
Field strength
Helium
Mathematical models
Optical pulses
Particle in cell technique
Photoionization
Physics
Relativistic plasmas
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Summary:Terahertz to far-infrared emission by two-color, ultrashort optical pulses interacting with underdense helium gases at ultrahigh intensities (>10^{19}  W/cm^{2}) is investigated by means of 3D particle-in-cell simulations. The terahertz field is shown to be produced by two mechanisms occurring sequentially, namely, photoionization-induced radiation (PIR) by the two-color pulse, and coherent transition radiation (CTR) by the wakefield-accelerated electrons escaping the plasma. We exhibit laser-plasma parameters for which CTR proves to be the dominant process, providing terahertz bursts with field strength as high as 100  GV/m and energy in excess of 10 mJ. Analytical models are developed for both the PIR and CTR processes, which correctly reproduce the simulation data.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.120.144801