Two‐Fluid Treatment of Whistling Behavior and the Warm Appleton‐Hartree Extension

Jonghe, Jordi De; Keppens, Rony

doi:10.1029/2020ja028953

Cited by 3 publications

(2 citation statements)

References 45 publications

(129 reference statements)

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“…These gaps are best seen for the DC = 12.6 and 12.6*2 Hz 1/2 s whistlers in Figures and . As first pointed out by (Gurnett et al., 1965), but using De Jonghe and Keppens (2020b) nomenclature, these gaps correspond to regions where F waves have been converted to A waves by passage through plasma having a significant concentration of H + ions. As shown in Figure 4a, the concentration of H + ions are expected to be negligible at and below the VAP altitude during the acquisition of the data shown in Figure 5, thus indicating that the wave echoes have traveled to higher altitude with higher H + concentrations prior to detection.…”

Section: Plasma Wave Observations Using Van Allen Probe Datamentioning

confidence: 94%

A Novel Population of Slow Magnetosonic Waves and a Method for the Observation of the Roots of Plasma Bubbles in the Lower Ionosphere

Bennett

2023

JGR Space Physics

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The mean global rate of lightning is 60 flashes/s (Burgesser, 2017) and is concentrated most strongly in the mid-latitude continental regions. The high global rate of lightning strokes, together with the low attenuation at low frequencies leads to the establishment of standing wave resonances within the Earth Ionospheric Waveguide (EIWG). Within the EIWG, the wave attenuation in the frequency range below 100 Hz is roughly 0.5 dB/Mm according to (Chapman et al., 1966), so that such low frequency waves may travel several times around the globe before losing most of their energy. The propagation of electromagnetic waves in the EIWG is discussed most extensively by Nickolaenko and Hayakawa (2002), see also (Budden, 1957;Jackson, 1975;Schumann, 1952). The resonances of the EIWG are known as the Schumann resonances (SRs). The transient vertical electric and horizontal magnetic fields at great distances from an individual strong lightning stroke, designated Q-bursts by Ogawa et al. (1967), appear as bipolar pulses in the time domain according to Nickolaenko et al. (2004), comprising a series of diminishing intensity delayed pulses corresponding to multiple Earth circuits.If the EIWG was a lossless, perfectly spherical cavity, the SR eigenfrequencies would bewhere R e is the Earth's radius, c is the speed of light, and n is the number of the eigenmode. In the actual EIWG, the frequencies of the lowest eigenmodes are only slightly lower than the values given by Equation 1, with observed values for the five lowest eigenmodes of 7.8, 14.1, 20.3, 26.3, and 32.5 Hz as listed in table 1 of Chapman et al. (1966). The corresponding quality factor Q values are 4, 4.5, 5, 5.5, and 6 for these resonances. Q values for a resonance at a given frequency are commonly defined as the ratio of the resonance frequency to

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Section: Plasma Wave Observations Using Van Allen Probe Datamentioning

confidence: 94%

A Novel Population of Slow Magnetosonic Waves and a Method for the Observation of the Roots of Plasma Bubbles in the Lower Ionosphere

Bennett

2023

JGR Space Physics

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“…These general and characteristic features of the classical whistler portion of the dispersion relations (De Jonghe & Keppens, 2020a, 2020b) are seen in observational data for whistlers in “normal” plasma regions, but are violated in regions of unusual dispersion.…”

Section: Wave Vector Analysis For Normal Whistler Eventsmentioning

confidence: 83%

Observations of the Roots of Plasma Bubbles: Are They Sometimes Foamy?

Bennett

2023

JGR Space Physics

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This article is a companion to Bennett (2023), that describes a novel method for the observation and analysis of the roots of equatorial plasma bubbles (EPBs). Most of the details in Bennett (2023) will not be repeated here, but a brief summary is presented in the following Section 2.EPBs are localized density depletions (sometimes by over four orders of magnitude relative to the surrounding plasma) in the nighttime equatorial ionosphere (Heelis, 2004;Kil & Heelis, 1998;Woodman & Hoz, 1976). The literature on EPBs is vast and spans nearly a century. Nowadays there is increasing motivation to understand such bubbles and their detrimental affects on radio communications, especially satellite communications, for which "loss of lock" events can be precipitated by their presence. Another detrimental effect is the disruption of signals from the Global Navigation Satellite System so important to modern society. Numerous reviews of the development of the experimental and theoretical understanding of plasma bubbles are available (e.g.,

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Polarization and properties of low-frequency waves in warm magnetized two-fluid plasma

Choi,

Woo,

Ryu

et al. 2023

Physics of Plasmas

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This paper presents the derivation of a general wave dispersion relation for warm magnetized plasma under the two-fluid formalism. The discussion is quite general except for the assumption of low frequency and slow phase speed, for which the displacement current is negligible, under the implicit assumption that the plasma is sufficiently dense to satisfy the condition ωpe>ωce, where ωpe and ωce denote the plasma oscillation frequency and electron gyro frequency, respectively. The present discussion does not invoke charge neutrality associated with the fluctuations although it is implicitly satisfied. The resulting dispersion relation that includes the fluid thermal effects shows that there are three eigen modes, which include those corresponding to ideal MHD, namely, fast, slow, and kinetic Alfvén waves, as well as higher-frequency modes including the ion and electron cyclotron and lower-hybrid resonances. The fluid effects in the ideal MHD wave branches are influenced by the finite Larmor radius scales, and when the wave number in the cross field direction is comparable to these values, the fluid effects become significant. It is found that the Larmor radius should be interpreted in the sense as ion-acoustic gyro-radius instead of ion thermal gyro radius only. That is, it is found that the electrons also contribute to the non-ideal effect associated with the kinetic Alfvén wave. A comprehensive explanation of the polarization of each mode is also presented. The present findings indicate that the polarity may change its sign only for the kinetic Alfvén mode branch and that such a transition is based on the propagation angle. When such a change does take place, it is found that the kinetic Alfvén wave transits to an ion-acoustic mode. For each branch, it is also found that the electric field along the ambient magnetic field is purely transverse.

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Two‐Fluid Treatment of Whistling Behavior and the Warm Appleton‐Hartree Extension

Abstract: The detection of whistler waves was first recorded in 1918 by radio operators who observed audio signals with a rapidly changing pitch (Barkhausen, 1919). Presently, they are covered in various plasma physics

Cited by 3 publications

References 45 publications

A Novel Population of Slow Magnetosonic Waves and a Method for the Observation of the Roots of Plasma Bubbles in the Lower Ionosphere

A Novel Population of Slow Magnetosonic Waves and a Method for the Observation of the Roots of Plasma Bubbles in the Lower Ionosphere

Observations of the Roots of Plasma Bubbles: Are They Sometimes Foamy?

Polarization and properties of low-frequency waves in warm magnetized two-fluid plasma

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