A new type of VLF emission triggered at low altitude in the subauroral region by Siple Station VLF transmitter signals

Bell, T. F.; Katsufrakis, J. P.; James, H. G.

doi:10.1029/ja090ia12p12183

Cited by 7 publications

(1 citation statement)

References 33 publications

(19 reference statements)

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“…The first suggestion that electrons could be lost from the radiation belts via cyclotron-resonant interactions was (remarkably) accompanied by a prediction that the same population could be artificially removed with radio wave transmitters; If…the failure of whistlers to remove the trapped radiation…is due to lack of power…it may be asked whether man-made transmitters can do better [Dungey, 1963]. Numerous studies have since suggested mechanisms to carry out this process-namely the artificial reduction of damaging fluxes of energetic electrons [e.g., Bell et al, 1985;Inan et al, 1985;Abel and Thorne, 1998;Rodger et al, 2006].…”

Section: Introductionmentioning

confidence: 99%

First optical observations of energetic electron precipitation at 4278 Å caused by a powerful VLF transmitter

Denton

Kosch

Borovsky

et al. 2014

Geophys. Res. Lett.

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A summary is presented of experimental optical observations at 4278 Å from close to a powerful (~150 kW) VLF transmitter (call sign JXN) with a transmission frequency of 16.4 kHz. Approximately 2.5 s after transmitter turn-on, a sudden increase in optical emissions at 4278 Å was detected using a dedicated camera/ charge-coupled device (CCD) monitoring system recording at a frequency of 10 Hz. The optical signal is interpreted as a burst of electron precipitation lasting~0.5 s, due to gyro-resonant wave-particle interactions between the transmitted wave and the magnetospheric electron population. The precipitation was centered on the zenith and had no detectable spatial structure. The timing of this sequence of events is in line with theoretical predictions and previous indirect observations of precipitation. This first direct measurement of VLF-induced precipitation at 4278 Å reveals the spatial and temporal extent of the resulting optical signal close to the transmitter.

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Section: Introductionmentioning

confidence: 99%

First optical observations of energetic electron precipitation at 4278 Å caused by a powerful VLF transmitter

Denton

Kosch

Borovsky

et al. 2014

Geophys. Res. Lett.

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VLF wave-injection experiments from Siple Station, Antarctica

Helliwell

1988

Advances in Space Research

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The background of VLF wave-particle experiments from Siple Station, Antarctica, including wave-induced precipitation is briefly reviewed. Single frequency ducted signals that exceed a certain 'threshold' intensity are observed at the conjugate point (Roberval, Quebec) to be amplified 30-50 dB, with temporal growth rates of 30-200 dB/s. Following saturation, variable frequency emissions are triggered. When a second signal is added to the first, with a frequency spacing DJ< 100 Hz, signal growth is reduced and sidebands are generated at frequencies separated from the carriers by integer multiples (up to seven) of D.f. The sidebands are attributed to short emissions triggered by the beats between the two input carriers. Mid-latitude magnetospheric hiss is crudely simulated by a sequence of 10 ms pulses whose frequencies are chosen randomly within a 400 Hz band. Results show that certain combinations of 10 ms pulses link together to form chorus-like elements, suggesting a common origin for hiss and chorus. Under conditions of strong echoing, emissions may form into lines; a recent example, started by the Siple Station transmitter, ex hibits interline spacings of about 45 Hz. These lines, called magnetospheric line radiation (MLR), vary slowly in frequency and show no simple connection to the harmonics of the Canadian power grid. Interline suppression may play a role in determining the spacing of MLR lines and the absence of discrete triggered emissions.

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Lower hybrid waves excited through linear mode coupling and the heating of ions in the auroral and subauroral magnetosphere

Bell¹,

Helliwell²,

Hudson³

1991

J. Geophys. Res.

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Experimental observations on the ISIS 1, ISIS 2, ISEE 1, and DE 1 spacecraft demonstrate that strong lower hybrid (LH) waves can be excited by VLF electromagnetic (em) whistler mode waves as the em waves propagate through regions of the ionosphere and magnetosphere where small‐scale magnetic‐field‐aligned irregularities exist in the mean plasma density. There is strong evidence that the LH waves are excited by linear mode coupling as the em waves scatter from the irregularities. The present paper considers two related aspects of the linear mode conversion mechanism: (1) the controlled heating of suprathermal ions in the ionosphere and magnetosphere over a powerful VLF/ELF transmitter using LH waves excited by the em transmitter signals through linear mode conversion; (2) the excitation of intense LH waves in the auroral regions through the linear conversion of VLF/ELF em auroral hiss, and the subsequent heating of ions by the excited LH waves. In addressing both aspects a critical feature is the behavior of the mode coupling mechanism at frequencies less than 10.2 kHz, the lowest value observed in earlier experiments. Using the results of controlled experiments carried out at Siple Station, Antarctica, it is demonstrated that strong LH waves can be excited by em waves down to frequencies as low as 2 kHz in the subauroral low‐altitude magnetosphere. Extrapolating from these observations and making use of ISEE 1 satellite wave amplitude data, we conclude that a ∼250 kW VLF/ELF transmitter operating in the subauroral region at 2 kHz could excite sufficiently intense LH waves to heat suprathermal 1 eV H+ ions and 16 eV O+ ions to roughly 50 eV in a region extending in altitude from 1000 to 5000 km above the transmitter with a horizontal scale of ∼500 km. Furthermore, if coherent wave stochastic heating occurs, the energy gain of O+ ions could be as large as 200 eV. This effect would be readily measurable with available satellite instrumentation. Using a recently developed model of the linear mode coupling mechanism, we furthermore conclude that a significant portion of the LH waves observed in the auroral zone in regions of ion conic development may be excited by em VLF/ELF auroral hiss as the hiss propagates through the irregular background plasma commonly observed in the auroral regions.

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A new type of VLF emission triggered at low altitude in the subauroral region by Siple Station VLF transmitter signals

Cited by 7 publications

References 33 publications

First optical observations of energetic electron precipitation at 4278 Å caused by a powerful VLF transmitter

First optical observations of energetic electron precipitation at 4278 Å caused by a powerful VLF transmitter

VLF wave-injection experiments from Siple Station, Antarctica

Lower hybrid waves excited through linear mode coupling and the heating of ions in the auroral and subauroral magnetosphere

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