Numerical Simulations of Elf/VLF Wave Generated by Modulated Beat-Wave Ionospheric Heating in High Latitude Regions

Abstract

Abstract-Based on the theory of ionospheric heating, with the self-consistent model in the low ionosphere, the Extremely-Low-Frequency (ELF) and Very-Low-Frequency (VLF) waves generated by modulated beat-wave ionospheric heating are analyzed theoretically. In the consideration of the stratified ionosphere, the magnetic fields generated by the equivalent ELF/VLF dipole source above the sea surface are studied by using the quasi-longitudinal approximation method. Taking the high latitude regions as an example, the variations of the electron temperature, the increments of Pedersen and Hall conductivities and the changing of the oscillating current density with the modulation frequency in beatwave heating are numerically discussed. The distribution of the magnetic fields is presented. It turns out that in high latitude regions, the efficiency of rectangular wave modulated heating in generating ELF/VLF wave is higher than that of modulated beat-wave heating, and the order of magnitude of the magnetic fields received above the sea surface is 10 −7 A/m in beat-wave modulation.

A Novel Method to Identify the Physical Mechanism and Source Region of ELF/VLF Waves Generated by Beat-Wave Modulation Using Preheating Technique

“…The validity of our physical model was verified by comparing our simulation results with [16]. The result (as shown in Figure 1) for comparison with our simulation is that of 20 November 2014, 1200 LT, the location of heating site is 69.6°N, 19.2°E (Tromsø, EIS-CAT), the parameters of the HF wave are 1.16 GW, X-wave [16].…”

“…The validity of our physical model was verified by comparing our simulation results with [16]. The result (as shown in Figure 1) for comparison with our simulation is that of 20 November 2014, 1200 LT, the location of heating site is 69.6°N, 19.2°E (Tromsø, EIS-CAT), the parameters of the HF wave are 1.16 GW, X-wave [16]. It is worth noting that the parameters of the heater above are not the real parameters of EISCAT, actually, they are the parameters of HAARP (High-frequency Active Auroral Research Program) [14].…”

“…where is the natural electric field, is the ionospheric conductivity. Two components of the ionospheric conductivity need to be considered in the modulation of electrojet, they are Pedersen conductivity and Hall conductivity [16]:…”

“…There is also a method called beat-wave (BW) modulation [10,11], but due to the controversy of its mechanism and the source region of the stimulated ELF/VLF waves, it is not clear whether it is an electrojet-independent method or not. Some scientists [12][13][14][15][16][17][18] believe that the source region of BW modulation is in the D region and the mechanism of beat-wave modulation is in essence consistent with AM (i.e., thermal nonlinearity) which is an electrojet-dependent modulation method. Others [19][20][21][22][23] hold the idea that the source region of BW modulation is in the F region, which means BW modulation is an electrojet-independent modulation method whose mechanism is ponderomotive nonlinearity.…”

Spatial Power Combining of VLF Umbrella Antenna Arrays With Multi-Delay Lines

“…Generally, a practical VLF transmitting antenna usually operates at high-voltage and high output power [2]. However, the radiation performance of the VLF antenna is limited by the solid state power-combining efficiency and the propagation characteristics of the ionosphere [3][4][5]. Overcoming the power limitations and compensating for the communication limits in high noise areas are the challenges in VLF communication [6].…”