Electromagnetic Response of the Mid‐Latitude Ionosphere to Power Transmission Lines

Abstract

Nowadays our planet exists in an electromagnetic environment, at least in some frequency bands, created by rather industrial activity than by natural processes. There appear ever growing evidences of man-made influence on natural geophysical processes (Parrot, 2018). This influence was found not only in dedicated active experiments, but also as unintentional by-product of the technosphere development (Rothkaehl & Parrot, 2005). The most ubiquitous type of electromagnetic radiation emanating from the Earth is the 50/60 Hz power line emission (PLE) (Pilipenko et al., 2021).The electromagnetic response of the ionosphere in the very-low-frequency (VLF) band (1-10 kHz) to natural and man-made electromagnetic disturbances (e.g., lightning, radio transmitters) has been thoroughly studied. In contrast to VLF emitters, any noticeable radiation efficiency in the extra-low-frequency (ELF) range (about several tens-hundreds of Hz) may be expected only for a very large emitting system. Such manmade large-scale transmitters do exist-they are networks of electric power transmission 50/60 Hz lines extended to many hundreds of km. A three-phase power transmission line must be balanced (symmetrical) when the voltages and currents of each of the phases have the same amplitude, and the phase shift is 0 120 E . If at least one of these conditions is not met, then the system becomes unbalanced. Such imbalance leads to a decrease in the efficiency of the transmission line and power losses due to the radiation of electromagnetic energy. In most cases, the source of the imbalance is the asymmetry of the load (high-speed railways, induction furnaces in metallurgy, computers, etc.). Substantial distortions into power line operation can be produced by geomagnetically induced currents (GICs) caused by rapid variations of the geomagnetic field, that is high dB dt / values. The detection of PLE at large distances from a three-phase power line is an indicator of its unbalanced operation. Moreover, due to strong non-linear elements (like thyristors) in industrial power lines high harmonics of the 50/60 Hz base frequency are generated. Power line harmonic radiation (PLHR) refers to VLF electromagnetic emissions at equidistant frequencies separated by 50/60 Hz. In this frequency range power lines can operate as running wave antenna (Beverage antenna) and be an efficient VLF emitter (Kostrov et al., 2017). PLHR can effectively penetrate into the ionosphere and magnetosphere and be detected by satellites (Nemec et al., 2006;Wu et al., 2014).

Active Precipitation of Radiation Belt Electrons Using Rocket Exhaust Driven Amplification (REDA) of Man‐Made Whistlers

“…In addition, ambient power‐line harmonics (Fedorov et al., 2021 ; Park & Helliwell, 1978 ), intentional VLF transmissions from terrestrial power lines and high‐power VLF transmitters can leak into space where they may interact with energetic electrons in the Earth's magnetosphere (Hua et al., 2020 ; Ma et al., 2017 ; Ross et al., 2019 ). Several man‐made facilities have been developed to study this wave‐particle‐interaction process including VLF transmitters (Helliwell, 1977 , 1988 ), high‐power HF facilities for modulations of natural ionosphere currents in the ionosphere (Guo et al., 2021 ), large satellite antennas driven by high power signal generators, electron beams that are modulated at VLF rates, and high‐speed neutral injections that rapidly photoionize in sunlight (Borovsky & Delzanno, 2019 ; Sotnikov et al., 2018 ).…”

Generation of artificial ULF/ELF electromagnetic emission in the ionosphere by horizontal ground-based current system

“…The geomagnetic field has been assumed to be vertical. The account for a finite inclination of the geomagnetic field will not modify the results considerably [Fedorov et al, 2021]. The geomagnetic field can provide some guidance of ELF emission, so as a result an equatorward shift of maximum response in the ionosphere to a ground transmitter should be observed.…”

“…[2020] presented a numerical model of electromagnetic response of a realistic ionosphere in the vertical geomagnetic field B 0 to a near-ground infinite linear current. This theoretical model was advanced in [Fedorov et al, 2021] by consideration of arbitrary geomagnetic field inclination and power line orientation. The account for a geomagnetic field inclination makes the problem significantly more complicated because the medium parameters become axially non-symmetric.…”

Power Line Harmonic Radiation Observed by the Van Allen Probes Spacecraft

“…PLHR events at frequencies corresponding to the first few harmonics have been recently analyzed using low-altitude spacecraft data (Dudkin et al, 2015;Korepanov et al, 2015). Such waves can readily penetrate through the ionosphere (Fedorov et al, 2020(Fedorov et al, , 2021Pilipenko et al, 2019). The event occurrence is ultimately related to the power consumption (Wu et al, 2017(Wu et al, , 2020 and their intensity is larger at times of stronger geomagnetically induced currents (Hayashi et al, 1978;Němec et al, 2015).…”