Gas pressure dependence of microwave pulses generated by laser-produced filament plasmas

Englesbe, Alexander; Elle, Jennifer; Reid, Remington; Lucero, Adrian; Pohle, Hugh; Domonkos, Matthew T.; Kalmykov, Serguei Y.; Krushelnick, K.; Schmitt-Sody, Andreas

doi:10.1364/ol.43.004953

Cited by 30 publications

(10 citation statements)

References 23 publications

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“…Since filamentation is dependent on the properties of the nonlinear medium the pulse is propagating through, it is expected that a change in air pressure and density will impact filament formation and properties. Several studies have shown the impact of air pressure on filament effects like microwave emission 15 , 16 and THz conversion 17 .…”

Section: Introductionmentioning

confidence: 99%

Filamentation in low pressure conditions

Pena

Reyes

Richardson

2022

Sci Rep

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Filamentation is favorable for many long-range outdoor laser applications, some of which require propagation to or at high altitudes. Understanding how the filamentation process and filament properties are impacted by the low pressure conditions present at high altitudes is essential in designing effective applications. The scaling of filament preconditions with pressure is considered. An increase in critical power and decrease in transition numerical aperture (NA) is predicted to occur with a drop in pressure, indicating that nonlinear pulse propagation and filamentation at high altitudes requires higher energy and a longer assisted focal length than sea level filamentation. A summary of pressure-scaled filament properties is also presented. New simulations demonstrate filamentation at pressures as low as 0.0035 atm (38.5 km altitude) is possible.

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Section: Introductionmentioning

confidence: 99%

Filamentation in low pressure conditions

Pena

Reyes

Richardson

2022

Sci Rep

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“…Its rotational current may emit a THz electromagnetic pulse (EMP), bearing information on the plasma stratification [9]- [11]. The EMP emission pattern, observed in the frequency range from GHz [12] to THz [13,14], may bear an imprint of wake currents.…”

Section: Introductionmentioning

confidence: 99%

Single-cycle THz signal accompanying laser wake in photoionized plasmas and plasma channels

Kalmykov,

Englesbe,

Elle

et al. 2020

Preprint

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Photoionization by a femtosecond, terawatt laser pulse generates a plasma column in a neutral ambient gas. Velocity of electrons, pushed by the laser ponderomotive force along the column surface, couples to the the radial density gradient at the column boundary, generating an azimuthally polarized THz rotational current (RC). The same mechanism produces the low-frequency RC in a leaky plasma channel. Applying external voltage to the channel induces a radially non-uniform electron flow (direct current) and a constant, azimuthally polarized magnetic field. Coupling them to the electron density perturbations adds two more terms to the RC. The surface RC in the plasma column supports a broadband, evanescent THz signal accompanying the wake. A few millimeters away from the column, rapid evanescence of high-frequency components turns this THz signal into a radially polarized, single-cycle pulse.

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“…and Brelet et al and Forestier et al have reported on a radio frequency (RF) antenna emission by LFs in air. In more recent studies, broadband emission stretching all the way down to the low-GHz range has been detected, − and multiband supercontinua stretching from the ultraviolet to the MMW band has been demonstrated …”

mentioning

confidence: 99%

“…The question as to whether or not this mechanism can efficiently emit radiation at even lower frequencies, extending deep into the microwave (μWv) range, is, however, far from trivial. Indeed, the canonical, well-established models of 1CD THz/sub-THz generation by longitudinal plasma currents ,, predict a low-frequency cutoff of broadband radiation output at around the plasma frequency, which for typical 1CD laser-ionization experiments ,, ranges from 0.3 to 10 THz. The spectrum of the low-frequency output in some of these experiments, however, extends well beyond this cutoff, reaching frequencies as low as a few GHz …”

mentioning

confidence: 99%

“…The spectrum of the low-frequency output in some of these experiments, however, extends well beyond this cutoff, reaching frequencies as low as a few GHz. 31 Understanding the spectral properties and the spatiotemporal mode structure of THz/μWv radiation from LP/LF sources is the key to identifying the physics behind low-frequency secondary radiation by laser-driven charges, currents, and plasmas. Because of the enormous, multidecade bandwidths and complex, frequency-dependent radiation patterns of such fields, experimental characterization of this radiation is anything but trivial.…”

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confidence: 99%

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Polarization and Spatial Mode Structure of Mid-Infrared-Driven Terahertz-to-Microwave Radiation

et al. 2021

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Polarization-and angle-resolved analysis of microwave-to-terahertz (μWv/THz) radiation from gas-phase plasmas induced by ultrashort mid-infrared laser pulses reveals a complex vectorial electrodynamic picture of μWv/THz generation by a diverse manifold of laser-driven plasma currents and provides a powerful tool to distinguish between currents of different spatial symmetries as sources of μWv/THz radiation. In experiments with a single-color mid-IR driver, the spatial mode of μWv/THz radiation is found to retain a remarkably uniform, conical-emission structure across its entire spectral span, with angular dispersion and a spatial mode profile as dictated by Cherenkov-type phase matching. This spatial mode structure is consistent with its polarization properties of μWv/THz radiation, indicating the dominant role of radiation by ponderomotively driven longitudinal currents. In experiments with a two-color laser driver, the spatialpolarization mode structure of μWv/THz radiation is found to change across its spectrum and as a function of the gas pressure, revealing mixed symmetries of underlying electric currents and indicating the shifting roles of transverse and longitudinal currents as mechanisms behind μWv/THz generation.

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Gas pressure dependence of microwave pulses generated by laser-produced filament plasmas

Cited by 30 publications

References 23 publications

Filamentation in low pressure conditions

Filamentation in low pressure conditions

Single-cycle THz signal accompanying laser wake in photoionized plasmas and plasma channels

Polarization and Spatial Mode Structure of Mid-Infrared-Driven Terahertz-to-Microwave Radiation

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