Modulation of auroral electrojet currents using dual modulated HF beams with ELF phase offset, a potential D‐region ionospheric diagnostic

: During the period of performance a program of instrument construction, technique development, data acquisition, and data analysis was carried out in order to characterize the auroral electrojet and the ambient and modified D-region directly above and near the HAARP (High Frequency Active Auroral Research Program) facility in Alaska. To accomplish this goal, five VLF D-region diagnostic systems were constructed and deployed in five High Schools near the HAARP facility and along the west coast of Alaska. In addition in order to characterize the auroral electrojet on a continental scale and to allow prediction of its location, four VLF D-region diagnostic systems were constructed and deployed in four High Schools on the east coast of the United States and Canada. Data from the complete array of D-region diagnostic systems was acquired during a number of Fall and Spring HAARP campaigns during the period of performance. This data was then used to determine the state of the D-region above HAARP during the campaigns and to provide information on the location of the auroral electrojet. The salient scientific results from the observations were published in the scientific literature and also reported at the annual RF Ionospheric Interactions Workshop in Santa Fe, New Mexico. In addition a portion of this data formed one of the bases of a Ph.D. dissertation completed at Stanford University.

This paper discusses research conducted by The Very Low Frequency (VLF) Group at Stanford University introducing them and a project called the High Frequency Active Auroral Research Program (HAARP). This project utilizes the latest oceanographic and ocean-engineering technologies for exciting applications to space physics and radio science research. Sponsors consist of the Air Force Research Laboratory (AFRL), the Naval Research Laboratory (NRL), and the Defense Advanced Research Projects Agency (DARPA). The program's facility is a high power transmitter located in Alaska, capable of broadcasting powerful VLF radio waves into the Earth's ionosphere. These waves propagate along the Earth's magnetic field lines to the system's geomagnetic conjugate point situated nominally 600 miles south of New Zealand in the southern Pacific Ocean. By studying the radio signals at this point, the VLF Group seeks to discover how energetic particles in the planet's radiation belts interact with very low frequency electromagnetic waves. This ambitious challenge of operating an autonomous, stationary, floating observation platform is known as the HAARP One-Hop Experiment - South Pacific Buoy.

Use of high frequency (HF) heating experiments has been extended in recent years as a useful methodology for plasma physicists wishing to remotely study the properties and behavior of the ionosphere as well as nonlinear plasma processes. Our recent work using high latitude heating experiments has lead to several important discoveries that have enabled assessment of active geomagnetic conditions, determination of minor ion species and their densities, ion mass spectrometry, electron temperature measurements in the heating ionosphere, as well a deeper understanding of physical processes associated with electron acceleration and formation of field aligned irregularities. All of these diagnostic capabilities have been made possible for the first time by utilizing the narrowband Stimulated Electromagnetic Emission SEE spectrum. Narrowband SEE spectra from the High Frequency Active Auroral Research Program (HAARP) facility are presented with theoretical models to demonstrate these new capabilities along with other supporting diagnostic measurements including, range-time-intensity of FAIs (field aligned irregularities) using SuperDARN HF radar, enhanced ion lines detected by MUIR radar, DMSP satellite observations over HAARP, and coordinated observations of pump induced optical emissions.

In a recent study, a process for the generation of Extremely Low Frequency (ELF) waves in the range of 1–12 Hz produced by diamagnetic currents generated by heat in ionosphere by high frequency (HF) waves has been proposed. HF waves that reach the ionosphere can be generated, for example, on the Earth's surface by the High Frequency Active Auroral Research Program (HAARP) instruments or solar processes. Using a EMF low frequency spectrum analyzer with high sensitivity (1 μΥ) operating in the range of 1–12 Hz and using a low sampling time (5 ms), it was possible to measure HF waves. A series of measurements were carried out in Sao Jose dos Campos, Brazil, from September, 2016 to March, 2017, under dry conditions and with the analyzer isolated from electrical discharges to detect and record these waves. The positive results of the experimental observations suggest a possible confirmation of the occurrence of diamagnetic currents in ionosphere.

Abstract. Artificial ionospheric plasmas descending from the background F-region have been observed on multiple occasions at the High Frequency Active Auroral Research Program (HAARP) facility since it reached full 3.6 MW power. Proximity of the transmitter frequency to the 2nd harmonic of the electron gyrofrequency (2fce) has been noted as a requirement for their occurrence, and their disappearance after only a few minutes has been attributed to the increasing frequency mismatch at lower altitudes. We report new experiments employing frequency sweeps to match 2fce in the artificial plasmas as they descend. In addition to revealing the dependence on the 2fce resonance, this technique reliably produces descending plasmas in multiple transmitter beam positions and appears to increase their stability and lifetime. High-speed ionosonde measurements are used to monitor the altitude and density of the artificial plasmas during both the formation and decay stages.

We compare observations of Stimulated Brillouin scattering produced during ionospheric modification experiments using ground-based high-power high frequency HF radio waves at both the High Frequency Active Auroral Research Program (HAARP) and the European Incoherent scatter (EISCAT).

Extremely Low Frequency (ELF) wave generation using the ionospheric heater at the High Frequency Active Auroral Research Program facility in Gakona, Alaska depends on electrojet currents. We use diagnostics from a radar, riometer, ionosonde, and magnetometer chain to understand how natural conditions affect ELF generation. We then present results of statistical models that show ELF amplitude is proportional to magnetometer measurements for a fixed value of riometer absorption, and that the proportionality constant decreases as riometer absorption increases. Numerical simulations using several ionospheric density profiles verify that denser profiles result in smaller gains for ELF generation than for electrojet current.

Spectrographic airglow measurements were made during an ionospheric modification experiment at High Frequency Active Auroral Research Program on 12 March 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert (1968, 1970), we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with heater‐induced ionization in view of the spatial intermittency of the airglow.

Ionospheric modification experiments have been performed at the High frequency Active Auroral Research Program involving the creation and suppression of artificial field‐aligned density irregularities (AFAIs) using O‐mode and X‐mode continuous wave emissions, respectively. The emission frequencies were offset so that the O‐mode upper hybrid interaction height nearly matched the X‐mode reflection height in the ionospheric E region. AFAIs created by O‐mode heating were observed using a 30 MHz coherent scatter radar imager. Simultaneous X‐mode heating was found to suppress the AFAI intensity and increase the threshold power for excitation by approximately a factor of 5 in our experiments. The effects are attributed in part to the broadening of the upper hybrid interaction region and in part to increased O‐mode absorption, which reduces the amplitude of the standing wave pattern in that region. Preliminary estimates based on local calculations suggest that the electron temperature in the E region was increased by a factor of about 1.6 in these experiments.

Artificial field‐aligned plasma density irregularities (FAIs) were generated in the E region of the ionosphere above the High Frequency Active Auroral Research Program facility during campaigns in May and August of 2012 and observed using a 30 MHz coherent scatter radar imager in Homer, Alaska. The purpose of this ionospheric modification experiment was to measure the threshold pump power required to excite thermal parametric instabilities by O‐mode heating and to investigate the suppression of the FAIs by simultaneous X‐mode heating. We find that the threshold pump power for irregularity excitation was consistent with theoretical predictions and increased by approximately a factor of 2 when X‐mode heating was present. A modified version of the Another Model of the Ionosphere (SAMI2) ionospheric model was used to simulate the threshold experiments and suggested that the increase was entirely due to enhanced D region absorption associated with X‐mode heating. Additionally, a remarkable degree of fine structure possibly caused by natural gradient drift instability in the heater‐modified volume was observed in experiments performed during geomagnetically active conditions.

Natural disasters like earthquakes, and global crises like pandemics have historically captured the public’s imagination and prompted people to seek explanations. However, in times of limited information, these explanations can take the form of conspiracy theories, particularly regarding the origins or causes of such events. With the advent of social media conspiracy theories can spread quickly and easily, leaving little room for critical thinking. The focus of this study is the analysis of the so-called High-Frequency Active Auroral Research Program (HAARP) conspiracy, which explains earthquakes through the employment of secret weather control weapons. This study aims to answer the research question of how the discourse on the HAARP conspiracy theory changes over time, and what are the potential catalysts for heightened attention to this conspiracy theory. This study uses the Twitter API to collect tweet frequencies about this conspiracy from January 2022 through March 2023. The empirical data include over one million tweets on HAARP. The sentiment analysis of the HAARP conspiracy theory is applied to the tweets before, during, and after the 6th of February 2023 earthquake in Syria and Turkey. In addition, this study investigates possible triggers of the development of the HAARP tweet frequency. This study finds that the frequency of HAARP discussion increases following a high-impact earthquake. There is also a positive correlation between average tweet sentiment and the number of tweets, which could indicate that the discussion of HAARP reinforces people’s beliefs. This study makes a significant contribution to the field of social psychology and communication by providing insights into the dynamics of belief reinforcement within online communities amidst heightened attention to conspiracy theories triggered by significant events. This knowledge has broader implications for understanding the impact of social media on public perception during crises.

Extremely-low-frequency (ELF, 3-3000 Hz) and very-low-frequency (VLF, 3-30 kHz) waves generated by the excitation of the thermal cubic nonlinearity are observed for the first time at the High-Frequency Active Auroral Research Program high-frequency transmitter in Gakona, Alaska. The observed ELF and VLF field amplitudes are the strongest generated by any high frequency (HF, 3-30 MHz) heating facility using this mechanism to date. This manner of ELF and VLF generation is independent of naturally forming currents, such as the auroral electrojet current system. Time-of-arrival analysis applied to experimental observations shows that the thermal cubic ELF and VLF source region is located within the collisional D-region ionosphere. Observations are compared with the predictions of a theoretical HF heating model using perturbation theory. For the experiments performed, two X-mode HF waves were transmitted at frequencies ω1 and ω2, with |ω2-2ω1| being in the ELF and VLF frequency range. In contrast with previous work, we determine that the ELF and VLF source is dominantly produced by the interaction between collision frequency oscillations at frequency ω2-ω1 and the polarization current density associated with the lower frequency HF wave at frequency ω1. This specific interaction has been neglected in past cubic thermal nonlinearity work, and it plays a major role in the generation of ELF and VLF waves.

High power radio waves excite electrostatic waves in the ionosphere. Electrostatic waves can be detected either by mode conversion into Stimulated Electromagnetic Emission (SEE) or scatter of radar signals. We present the results of SEE observations conducted through high-power HF heating experiments at the High-Frequency Active Auroral Research Program. Multiple receiving instruments have been used to observe many low frequency electrostatic modes from a high power electromagnetic pump. These modes are not well characterized. Our ionospheric heating experiments are attempts to understand the process by which an electromagnetic pump wave is converted into high and low-frequency modes.

Artificial E region field‐aligned plasma density irregularities (AFAIs) have been generated using the High‐frequency Active Auroral Research Program (HAARP) ionospheric modification facility in Gakona and observed with a 30 MHz coherent scatter radar imager in Homer, Alaska. The AFAIs were generated using a distinctive, twisted‐beam antenna pattern that illuminated a particularly broad volume overhead. The broad beam facilitates studies of natural sporadic E layer patches when they are present. The center of the pattern was pointed at different angles between zenith and magnetic zenith to examine the effects on the AFAI morphology. Radar images of AFAIs generally resemble the radiation pattern of the high‐frequency source, but the irregularities are strongest within a narrow range of zenith angles bounded approximately by the Spitze angle. A number of factors which might influence AFAI generation and detection are examined. The most important is most likely the requirement for the pump mode to have a standing‐wave component for thermal parametric instability to operate.

Modulation of the beam current has been observed during ion focused regime (IFR) transport of a high-power relativistic electron beam propagating through a low-density background plasma. In this experiment, a 1.7-MeV, 1-kA, risetime-sharpened electron beam is transported in a KrF excimer laser produced IFR channel in TMA gas. The IFR channel is immersed in a low-density plasma filled transport tube. We present experimental measurements and computer simulations demonstrating modulation of this high-current relativistic electron beam near the low-density background plasma frequency.