Slow Z-mode radiation from sounder-accelerated electrons

James, H. G.

doi:10.1016/j.jastp.2004.07.035

Cited by 9 publications

(9 citation statements)

References 12 publications

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“…Evidence for this is given here and in the work by M98. James [2004] observed a somewhat similar effect; he deduced that slow‐Z reradiation occurred from sounder‐accelerated electrons.…”

Section: Discussionmentioning

confidence: 99%

The Poynting vector applied to the complex refractive index in a hot plasma near the electron cyclotron frequency and to the cyclotron resonance observed on topside ionograms

Muldrew

2006

Radio Science

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[1] The electron cyclotron resonance is the only fundamental resonance observed on topside ionograms that, up to the present, has not been understood. There is a solution to the hot plasma dispersion equations for the wave frequency f near the cyclotron frequency f H when the wave number k makes a small angle to the Earth's magnetic induction B. For this case, the magnitude of the imaginary part of k is more than half the real part. This means that the group velocity, dw/dk, where w = 2p f, is complex. The real part of dw/dk is too large to explain the cyclotron resonance observations. In addition to the wave number, the dispersion relations for a hot magnetoplasma can be used to obtain the electric and magnetic fields of the cyclotron wave and hence the Poynting vector. Dividing the Poynting energy flux by the energy density of the wavefield, where the energy density is the sum of the electric, magnetic, and electron energy densities, gives the Poynting velocity V P , which is a good approximation to the actual wave energy velocity for f near f H . Cyclotron waves are strongly damped but can exist several milliseconds as observed. The waves radiate from the plane containing B and the dipole antenna L. The waves with f > f H beat with those with f < f H to produce the beat frequency observed on fixed-frequency ionograms.Citation: Muldrew, D. B. (2006), The Poynting vector applied to the complex refractive index in a hot plasma near the electron cyclotron frequency and to the cyclotron resonance observed on topside ionograms, Radio Sci., 41, RS6006,

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Section: Discussionmentioning

confidence: 99%

The Poynting vector applied to the complex refractive index in a hot plasma near the electron cyclotron frequency and to the cyclotron resonance observed on topside ionograms

Muldrew

2006

Radio Science

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“…Particle detectors on both payloads detected SAE following sounder transmissions from the transmitting payload. James [37] could reproduce the observed signal delay times and could predict (within an order of magnitude) the observed signal intensities. …”

Section: Dual Payloads: Slow Zmentioning

confidence: 68%

“…Again, the sounder-transmitter was on one payload and the sounder-receiver was on the other, and the separation direction between the payloads, now separated by more than a 1 km, differed from the B direction by only a few degrees. In this case, James [37] investigated the slow Z-mode propagation corresponding to f pe < f ce < f < f uh , i.e., to the CMA-region 3 of Fig. 1.2b.…”

Section: Dual Payloads: Slow Zmentioning

confidence: 99%

Active Wave Experiments in Space Plasmas: The Z Mode

Benson

Webb

Green

et al.

Geospace Electromagnetic Waves and Radiation

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Abstract. The term Z mode is space physics notation for the low-frequency branch of the extraordinary (X) mode. It is an internal, or trapped, mode of the plasma confined in frequency between the cutoff frequency fz and the upper-hybrid frequency f uh which is related to the electron plasma frequency fpe and the electron cyclotron frequency fce by the expression f; fz is a function of fpe and fce. These characteristic frequencies are directly related to the electron number density Ne and the magnetic field strength |B|, i.e., fpe (kHz) 2 ≈ 80.6Ne(cm −3 ) and fce (kHz) 2 ≈ 0.028|B|(nT). The Z mode is further classified as slow or fast depending on whether the phase velocity is lower or higher than the speed of light in vacuum. The Z mode provides a link between the short wavelength λ (large wave number k = 2π/λ ) electrostatic (es) domain and the long λ (small k) electromagnetic (em) domain. An understanding of the generation, propagation and reception of Z-mode waves in space plasma leads to fundamental information on wave/particle interactions, Ne, and field-aligned Ne irregularities (FAI) in both active and passive wave experiments. Here we review Z-mode observations and their interpretations from both radio sounders on rockets and satellites and from plasma-wave receivers on satellites. The emphasis will be on the scattering and ducting of sounder-generated Z-mode waves by FAI and on the passive reception of Z-mode waves generated by natural processes such as Cherenkov and cyclotron emission. The diagnostic applications of the observations to understanding ionospheric and magnetospheric plasma processes and structures benefit from the complementary nature of passive and active plasma-wave experiments.

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“…Comprehensive studies of the SAE were performed in the sounding rocket OEDIPUS-C experiment (Huang et al, 2001;James, 2004;James et al, 1999). In this experiment, two suites of particle instruments were accommodated on two separate platforms connected by an electrically conducting tether.…”

Section: 1029/2019ja027206mentioning

confidence: 99%

Observations of Sounder Accelerated Electrons by Mars Express

et al. 2020

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The electron sensor of the Analyzer of Space Plasmas and Energetic Atoms experiment detects accelerated electrons during pulses of radio emissions from the powerful topside sounder: the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board the Mars Express spacecraft. Accelerated electrons are observed at energies up to 400 eV at the times when MARSIS transmits at a frequency between the local plasma frequency and its harmonics (up to 4 times the plasma frequency). When the electron density and magnetic field strength are low (∼ 10 3 cm −3 , ∼ 10 nT), the accelerated electrons are almost monoenergetic electron beams. An increase in density and magnetic field (∼ 3 · 10 3 cm −3 , ∼ 50 nT) leads to substantial broadening of the energy spectrum of the accelerated electrons. It is concluded that in the latter case, electrons are accelerated by the variable spacecraft potential resulting from the imbalance of the electron and ion currents to the MARSIS antenna during transmission.

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Slow Z-mode radiation from sounder-accelerated electrons

Cited by 9 publications

References 12 publications

The Poynting vector applied to the complex refractive index in a hot plasma near the electron cyclotron frequency and to the cyclotron resonance observed on topside ionograms

The Poynting vector applied to the complex refractive index in a hot plasma near the electron cyclotron frequency and to the cyclotron resonance observed on topside ionograms

Active Wave Experiments in Space Plasmas: The Z Mode

Observations of Sounder Accelerated Electrons by Mars Express

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