Heater‐induced ionization inferred from spectrometric airglow measurements

Hysell, D. L.; Miceli, R. J.; Kendall, E. A.; Schlatter, Nicola; Varney, R. H.; Watkins, B. J.; Pedersen, T. R.; Bernhardt, P. A.; Huba, J. D.

doi:10.1002/2013ja019663

Cited by 8 publications

(21 citation statements)

References 32 publications

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“…In and of itself, the 777.4 emission is unequivocal proof that at Arecibo we had HF accelerated electron fluxes accelerated to energies ~11 eV. Within the context of their persistence and the persistence of plasma line enhancements observed previously (Carlson et al 1982), plus the experimental and theoretical evidence for spectral flatness across 10-20 eV (Carlson et al 1982;Gurevich et al 2000), we conclude that observation of 777.4 nm and 844.6 nm (Hysell et al 2014) emissions (10.74, 10.99 eV) are a good surrogate for presence of HF electron fluxes in the ionizing range (13-19 eV).…”

Section: Discussionsupporting

confidence: 69%

“…Gustavsson et al (2005) used optical emissions to set parameters in a physics based model, but then returned in Gustavsson and Eliasson (2008) to notably improve realism of the findings by adding altitude dependencies of fluxes. Hysell et al (2014) introduced and applied a method to estimate the suprathermal electron population versus altitude and energy, during an F region HF ionospheric modification experiment, on the basis of observed emissions and an inversion method based on a variation of the classic Backus and Gilbert (1970) approach, including utilization of Green's functions to reduce the dimensionality of the problem. The nonparametric method was in contrast to the Gustavsson and Eliasson (2008) approach using airglow emissions to set the parameters of a physics-based electron acceleration model.…”

Section: Discussionmentioning

confidence: 99%

“…They do a thorough listing of the competing crosssections, including N 2 vibrational excitation essential to the composite electron impact cross-sections in the 1.5-5 eV range (Itikawa 2006). The Hysell et al (2014) work was motivated by not overly constricting derived spectra to input assumptions about a spectral shape from a theory still in development. Sergienko et al (2012) have explored improvement in electron transport with a Monte Carlo method.…”

Section: Discussionmentioning

confidence: 99%

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HF Accelerated Electron Fluxes, Spectra, and Ionization

Carlson

Jensen

2014

Earth Moon Planets

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Wave particle interactions, an essential aspect of laboratory, terrestrial , and astrophysical plasmas, have been studied for decades by transmitting high power HF radio waves into Earth's weakly ionized space plasma, to use it as a laboratory without walls. Application to HF electron acceleration remains an active area of research (Gurevich, 2007) today. HF electron acceleration studies began when plasma line observations proved (Carlson et al, 1982) that high power HF radio wave-excited processes accelerated electrons not to ~ eV, but instead to -100 times thermal energy (10s of eV), as a consequence of inelastic collision effects on electron transport.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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HF Accelerated Electron Fluxes, Spectra, and Ionization

Carlson

Jensen

2014

Earth Moon Planets

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“…Sergeev et al [2013] explored DL using concurrent measurements of SEE, reflected probing signals, and MUIR plasma line (PL) backscatter during frequency-stepping experiments around 4f ce . The DL-associated optical emissions at ≈732 nm and 427.8 nm (the blue line) indicate electron acceleration above the ionization energies ion [Pedersen et al, 2010;Hysell et al, 2014]. These results concern pencil-like radio beams.…”

Section: Uh/eb Waves Can Be Excited Via Decay Pd Omentioning

confidence: 78%

Artificial ionospheric layers driven by high‐frequency radiowaves: An assessment

et al. 2016

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High‐power ordinary mode radio waves produce artificial ionization in the F region ionosphere at the European Incoherent Scatter (Tromsø, Norway) and High Frequency Active Auroral Research Program (Gakona, Alaska, USA) facilities. We have summarized the features of the excited plasma turbulence and descending layers of freshly ionized (“artificial”) plasma. The concept of an ionizing wavefront created by accelerated suprathermal electrons appears to be in accordance with the data. The strong Langmuir turbulence (SLT) regime is revealed by the specific spectral features of incoherent radar backscatter and stimulated electromagnetic emissions. Theory predicts that the SLT acceleration is facilitated in the presence of photoelectrons. This agrees with the intensified artificial plasma production and the greater speeds of descent but weaker incoherent radar backscatter in the sunlit ionosphere. Numerical investigation of propagation of O‐mode waves and the development of SLT and descending layers have been performed. The greater extent of the SLT region at the magnetic zenith than that at vertical appears to make magnetic zenith injections more efficient for electron acceleration and descending layers. At high powers, anomalous absorption is suppressed, leading to the Langmuir and upper hybrid processes during the whole heater on period. The data suggest that parametric upper hybrid interactions mitigate anomalous absorption at heating frequencies far from electron gyroharmonics and also generate SLT in the upper hybrid layer. The persistence of artificial plasma at the terminal altitude depends on how close the heating frequency is to the local gyroharmonic.

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“…[] and Hysell et al . []. Ionization potentials for atomic oxygen O, N 2 , and O 2 are respectively 13.62, 15.58, and 12.06 eV.…”

Section: Theoretical Context For Hf‐produced Ionization At High Versumentioning

confidence: 99%

Creating space plasma from the ground

2017

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We have performed an experiment to compare as directly as realizable the ionization production rate by HF radio wave energy versus by solar EUV. We take advantage of the commonality that ionization production by both ground‐based high‐power HF radio waves and by solar EUV is driven by primary and secondary suprathermal electrons near and above ~20 eV. Incoherent scatter radar (ISR) plasma‐line amplitudes are used as a measure of suprathermal electron fluxes for ISR wavelengths near those for 430 MHz and are indeed a clean measure of such for those fluxes sufficiently weak to have negligible self‐damping. We present data from an HF heating experiment on November 2015 at Arecibo, which even more directly confirm the only prior midlatitude estimate, of order 10% efficiency for conversion of HF energy to ionospheric ionization. We note the theoretical maximum possible is ~1/3, while ~1% or less reduces the question to near practical irrelevance. Our measurements explicitly confirm the prediction that radio‐frequency production of artificial ionospheres can be practicable, even at midlatitudes. Furthermore, that this midlatitude efficiency is comparable to efficiencies measured at high latitudes (which include enhancements unique to high latitudes including magnetic zenith effect, gyrofrequency multiples, and double resonances) requires reexamination of current theoretical thinking about soft‐electron acceleration processes in weakly magnetized plasmas. The implications are that electron acceleration by any of a variety of processes may be a fundamental underpinning to energy redistribution in space plasmas.

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Heater‐induced ionization inferred from spectrometric airglow measurements

Cited by 8 publications

References 32 publications

HF Accelerated Electron Fluxes, Spectra, and Ionization

HF Accelerated Electron Fluxes, Spectra, and Ionization

Artificial ionospheric layers driven by high‐frequency radiowaves: An assessment

Creating space plasma from the ground

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