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Title: Laser pulse driven terahertz generation via resonant transition radiation in inhomogeneous plasmas

An intense, short laser pulse propagating across a plasma boundary ponderomotively drives THz radiation. In this paper, full format PIC simulations and theoretical analysis are conducted to investigate the properties of this radiation. Simulation results which show the THz emission originates in regions of varying density and covers a broad spectrum with maximum frequency close to the maximum plasma frequency. In the case of a sharp vacuum-plasma boundary, the radiation is generated symmetrically at the plasma entrance and exit, and its properties are independent of plasma density when the density exceeds a characteristic value determined by the product of the plasma frequency and the laser pulse duration. For a diffuse vacuum-plasma boundary, the emission from the plasma entrance and exit is asymmetric: increasing and decreasing density ramps enhance and diminish the radiated energy, respectively. Enhancements by a factor of 50 are found and simulations show that a 1.66 J, 50 fs driver pulse can generate ~400 μJ of THz radiation in a 1.2 mm increasing density ramp. We present a model that attributes this effect to a plasma resonance process in the density ramp. The results from the model match those of the simulations for ramp lengths less than 600more » μm. Finally, for longer ramps for which simulations are too time consuming, the model shows that the amount of radiation reaches a maximum at a ramp length determined by collisional absorption.« less
Authors:
ORCiD logo [1] ;  [2] ;  [1]
  1. Univ. of Maryland, College Park, MD (United States). Inst. for Research in Electronics and Applied Physics
  2. Naval Research Lab. (NRL), Washington, DC (United States)
Publication Date:
Grant/Contract Number:
SC0010741; N00173131G018
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 6; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Maryland, College Park, MD (United States); Naval Research Lab. (NRL), Washington, DC (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25); Office of Naval Research (ONR) (United States)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; electron density; plasma acceleration; transition radiation; plasma waves; plasma density; coherent radiation; optical phase matching; electrodynamics; terahertz radiation sources; laser plasma interactions
OSTI Identifier:
1471517
Alternate Identifier(s):
OSTI ID: 1255630

Miao, Chenlong, Palastro, John P., and Antonsen, Thomas M.. Laser pulse driven terahertz generation via resonant transition radiation in inhomogeneous plasmas. United States: N. p., Web. doi:10.1063/1.4953098.
Miao, Chenlong, Palastro, John P., & Antonsen, Thomas M.. Laser pulse driven terahertz generation via resonant transition radiation in inhomogeneous plasmas. United States. doi:10.1063/1.4953098.
Miao, Chenlong, Palastro, John P., and Antonsen, Thomas M.. 2016. "Laser pulse driven terahertz generation via resonant transition radiation in inhomogeneous plasmas". United States. doi:10.1063/1.4953098. https://www.osti.gov/servlets/purl/1471517.
@article{osti_1471517,
title = {Laser pulse driven terahertz generation via resonant transition radiation in inhomogeneous plasmas},
author = {Miao, Chenlong and Palastro, John P. and Antonsen, Thomas M.},
abstractNote = {An intense, short laser pulse propagating across a plasma boundary ponderomotively drives THz radiation. In this paper, full format PIC simulations and theoretical analysis are conducted to investigate the properties of this radiation. Simulation results which show the THz emission originates in regions of varying density and covers a broad spectrum with maximum frequency close to the maximum plasma frequency. In the case of a sharp vacuum-plasma boundary, the radiation is generated symmetrically at the plasma entrance and exit, and its properties are independent of plasma density when the density exceeds a characteristic value determined by the product of the plasma frequency and the laser pulse duration. For a diffuse vacuum-plasma boundary, the emission from the plasma entrance and exit is asymmetric: increasing and decreasing density ramps enhance and diminish the radiated energy, respectively. Enhancements by a factor of 50 are found and simulations show that a 1.66 J, 50 fs driver pulse can generate ~400 μJ of THz radiation in a 1.2 mm increasing density ramp. We present a model that attributes this effect to a plasma resonance process in the density ramp. The results from the model match those of the simulations for ramp lengths less than 600 μm. Finally, for longer ramps for which simulations are too time consuming, the model shows that the amount of radiation reaches a maximum at a ramp length determined by collisional absorption.},
doi = {10.1063/1.4953098},
journal = {Physics of Plasmas},
number = 6,
volume = 23,
place = {United States},
year = {2016},
month = {6}
}