Plasma Wave Receiver Research Articles

Oblique Electrostatic Solitary and Supersolitary Waves in Earth’s Magnetosheath

Nonlinear electrostatic solitary waves (ESWs) are routinely detected at various regions of Earth’s magnetosphere using the Wideband Data plasma wave receivers mounted on board the Cluster satellite(s). This mission has facilitated the observation and analysis of ESW characteristics, such as amplitude and temporal duration within the magnetosheath, while concurrently determining the density and temperature profiles of energetic electrons. These electron parameters, in conjunction with data from ion experiments, have served as input for the ion-acoustic solitary wave model developed in this article, with the ambition to contribute to the understanding of ESW generation mechanisms. Assuming as the starting point a plasma system comprising inertial ion fluid and kappa-distributed electron populations of different temperatures (i.e., “cold” and “hot” electrons), a nonperturbative approach has been adopted to investigate the existence and properties of solitary waves. A thorough parametric investigation has scrutinized the existence conditions for such localized structures in terms of the plasma configuration parameters. An interesting aspect emerges from the analysis, namely, the possibility for the coexistence of positive and negative polarity structures associated with ion-acoustic modes, in fact, manifested as simultaneously occurring positive polarity supersolitary waves and negative polarity regular solitary waves. Furthermore, our study has investigated the combined effect of the magnetic field strength, electron density, and suprathermal electron statistics on wave dynamics. The outcomes of this research are in agreement with observed electrostatic wave phenomena in the magnetosheath region, thus underscoring the intrinsic relevance of electrostatic supersolitary structures in data obtained by Cluster and other satellite missions.

The Whistler Traveling Wave Parametric Amplifier Driven by an Ion-Ring Beam Distribution from a Neutral Gas Injection in Space Plasmas

A new parametric amplifier model describes the observations of intensified whistler waves produced by a dedicated burn of the BT-4 engine on the Cygnus spacecraft during the NG-13 mission. Ground very low frequency (VLF) radio emissions at 25.2 kHz from a Navy NML transmitter in North Dakota were amplified by 20-30 dB during the Cygnus burn at 480-km altitude and recorded at 1060 km by the e-POP/RRI plasma wave receiver on the SWARM-E satellite. The amplification process starts with charge exchange between the exhaust molecules and the ambient O+ in the ionosphere to produce water vapor ions that spiral around the earth's magnetic field lines. This ion-velocity-ring distribution generates broadband, oblique-lower-hybrid (OLH) waves, which act as a pump for the parametric amplifier. The nonlinear ponderomotive force on the electrons causes the high-amplitude OLH pump to mix with the input whistler signal, yielding an OLH idler wave. Resonant mixing of the pump and idler electric fields promotes temporal growth in the amplitude of the whistler waves as they propagate through the exhaust cloud. The key features to rocket exhaust-driven amplification (REDA) process are broadband gain, bi-directionality along the magnetic field, pump depletion, phasing, and feedback. Pump depletion limits the intensity of the output whistler waves by wave energy conservation. The total wave energy is the electrostatic energy of the pump and idler lower hybrid waves plus the energy extracted by the propagating whistler signal. The whistler traveling wave parametric amplifier provides an efficient mechanism for active amplification of signals in space.

Plasma Wave Observation in Space Via Scientific Satellites

Space plasmas are essentially collisionless. Kinetic energies of plasmas are transferred through wave-particle interactions. Since plasmas are dispersive media, plasma waves show various features depending on how and which plasma wave modes interact with particles. Plasma wave observations via scientific satellites have a key role in knowing physical processes in space. Plasma wave investigation systems on board satellites are dedicated to the observations of electric field and magnetic field components of plasma waves. They consist of sensors, receivers and an onboard digital processing unit. While dipole antennas are used for electric field sensors, search coil magnetometers or loop antennas are used for magnetic field sensors. Plasma wave receivers are a kind of sophisticated radio receivers. The recent plasma wave receiver is designed as a waveform receiver that can save its mass and size. In addition to waveforms, the waveform receiver provides frequency spectra which are calculated in the digital processing unit from the observed waveforms. The present paper introduces plasma wave observation by scientific satellites on the basis of the latest design of plasma wave investigation systems.

Development of a miniaturized spectrum-type plasma wave receiver comprising an application-specific integrated circuit analog front end and a field-programmable gate array

Plasma waves are an important target for satellite-based in situ observation to understand electromagnetic phenomena in space. Recent scientific satellites have carried fast Fourier transform (FFT)-based spectrum receivers; however, such receivers have a disadvantage because they use wideband analog parts. The new receiver overcomes the disadvantage by adding bandlimiting in the first stage of the analog part, and it covers the entire observation frequency range of each band by switching its cutoff frequency. In order to miniaturize circuit size, the new receiver comprises application-specific integrated circuits (ASICs) and a field-programmable gate array (FPGA). The ASIC chip includes the analog part of the receiver and the analog-to-digital converter, and the FPGA includes an FFT module and the controller of the receiver. The proposed spectrum receiver was successfully implemented with a size of 55 mm × 80 mm × 35 mm and a total power consumption of 948.3 mW. The time resolution of the receiver was 112 ms, and the frequency resolutions for frequency bands from 10 Hz to 1 kHz, from 1 kHz to 10 kHz, and from 10 kHz to 100 kHz were 13 Hz, 130 Hz, and 1.3 kHz, respectively. Overall, the developed receiver showed sufficient performance for plasma wave observation.

One-chip analog circuits for a new type of plasma wave receiver on board space missions

Abstract. Plasma waves are important observational targets for scientific missions investigating space plasma phenomena. Conventional fast Fourier transform (FFT)-based spectrum plasma wave receivers have the disadvantages of a large size and a narrow dynamic range. This paper proposes a new type of FFT-based spectrum plasma wave receiver that overcomes the disadvantages of conventional receivers. The receiver measures and calculates the whole spectrum by dividing the observation frequency range into three bands: bands 1, 2, and 3, which span 1 Hz to 1 kHz, 1 to 10 kHz, and 10 to 100 kHz, respectively. To reduce the size of the receiver, its analog section was realized using application-specific integrated circuit (ASIC) technology, and an ASIC chip was successfully developed. The dimensions of the analog circuits were 4.21 mm × 1.16 mm. To confirm the performance of the ASIC, a test system for the receiver was developed using the ASIC, an analog-to-digital converter, and a personal computer. The frequency resolutions for bands 1, 2, and 3 were 3.2, 32, and 320 Hz, respectively, and the average time resolution was 384 ms. These frequency and time resolutions are superior to those of conventional FFT-based receivers.

Frequency range of dust detection in space with radio and plasma wave receivers: Theory and application to interplanetary nanodust impacts on Cassini

AbstractWave instruments can detect dust in space via the charges released by impact ionization of fast dust grains. Each hypervelocity dust impact produces an electrostatic pulse whose short risetime is a major property determining the frequency range of detection. We propose a simplified analytical model to calculate this risetime and its variation with grains' mass and photoelectron or ambient plasma density, for pulses in spacecraft potential due to fast interplanetary nanodust impacts. We test these calculations by analyzing the high‐frequency receiver data of the radio and plasma wave instrument during the cruise phase of the Cassini mission between Earth and Jupiter. These data confirm the dependence of the risetime on grains' mass and speed and heliocentric distance predicted by our calculations. Furthermore, the data show that the nanodust properties follow closely the fluctuations of the solar wind velocity component perpendicular to the magnetic field, as predicted by dynamics. The calculations can be generalized to microdust detection on other spacecraft and might explain previous observations left uninterpreted. These calculations are also relevant for the design of wave receivers, by determining the optimal frequency range for dust detection on future missions.

Small sensor probe for measuring plasma waves in space

Since conventional one-point observations of plasma phenomena in space cannot distinguish between time and spatial variations, the missions on the basis of multiple-point observations have become the trend. We propose a new system for multiple-point observation referred to as the monitor system for space electromagnetic environments (MSEE). The MSEE consists of small sensor probes that have a capability to measure electromagnetic waves and transfer received data to the central station through wireless communication. We developed the prototype model of the MSEE sensor probe. The sensor probe includes a plasma wave receiver, the microcontroller, the wireless communication module, and the battery in the 75-mm cubic housing. In addition, loop antennas, dipole antennas, and actuators that are used for expanding dipole antennas are attached on the housing. The whole mass of the sensor probe is 692 g, and the total power consumption is 462 mW. The sensor probe can work with both inner battery and external power supply. The maximum continuous operation time on battery power is more than 6 h. We verified the total performance for electric field measurements by inputting signal to preamplifier. In this test, we found that analog components had enough characteristics to measure electric fields, and the A/D conversion and the wireless transmission worked correctly. In the whole performance for electric fields, the sensor probe has equivalent noise level of $$ -135 \mathrm{d}\mathrm{B}\mathrm{V}/\mathrm{m}/\sqrt{\mathrm{Hz}} $$ . We succeed in developing the prototype model of the small sensor probe that had enough sensitivity for electric field to measure plasma waves and the ability to transfer observation data through wireless communication. The success in developing the small sensor probe for the measurement of plasma waves leads to the realization of the multiple-point observations using a lot of small probes scattered in space.

A new method for direction finding based on Markov random field model

AbstractInvestigating the characteristics of plasma waves observed by scientific satellites in the Earth's plasmasphere/magnetosphere is effective for understanding the mechanisms for generating waves and the plasma environment that influences wave generation and propagation. In particular, finding the propagation directions of waves is important for understanding mechanisms of VLF/ELF waves. To find these directions, the wave distribution function (WDF) method has been proposed. This method is based on the idea that observed signals consist of a number of elementary plane waves that define wave energy density distribution. However, the resulting equations constitute an ill‐posed problem in which a solution is not determined uniquely; hence, an adequate model must be assumed for a solution. Although many models have been proposed, we have to select the most optimum model for the given situation because each model has its own advantages and disadvantages. In the present study, we propose a new method for direction finding of the plasma waves measured by plasma wave receivers. Our method is based on the assumption that the WDF can be represented by a Markov random field model with inference of model parameters performed using a variational Bayesian learning algorithm. Using computer‐generated spectral matrices, we evaluated the performance of the model and compared the results with those obtained from two conventional methods.

Interpretation of Cluster WBD frequency conversion mode data

Abstract. The Cluster wide-band data (WBD) plasma wave receiver mounted on each of the four Cluster spacecraft obtains high time resolution waveform data in the frequency range of ~70 Hz to 577 kHz. In order to make measurements above 77 kHz, it uses frequency conversion to sample the higher frequency waves at one of three different conversion frequencies (~125, 250 and 500 kHz, these frequencies being the possible options for setting the base frequency of the frequency range being sampled) in one of three different filter bandwidths (9.5, 19 and 77 kHz). Within the WBD instrument, a down-conversion technique, built around quadrature mixing, is used to convert these data to baseband (0 kHz) in order to reduce the sample rate for telemetry to the ground. We describe this down-conversion technique and illustrate it through data obtained in space. Because these down-converted data sometimes contain pulses, which can be indicative of nonlinear physical structures (e.g., electron phase-space holes and electron density enhancements and depletions), it is necessary to understand what effects mixing and down conversion have on them. We present simulations using constructed signals containing pulses, nonlinear wave packets, sinusoids and noise. We show that the pulses and impulsive wave packets, if of sufficient amplitude and of appropriate width, survive the down-conversion process, sometimes with the same pulse shape but usually with reduced amplitude, and have timescales consistent with the filter bandwidth at the base frequency. Although we cannot infer the actual timescale of the pulses and impulsive wave packets as originally recorded by the WBD instrument before mixing and down conversion, their presence indicates nonlinear processes occurring at or somewhat near the location of the measurement. Sinusoidal waves are represented in the down-conversion timescale as sinusoids of nearly the same amplitude and at frequencies adjusted down by the conversion frequency. The original input waveforms, regardless of their shape, whether pulses or sinusoids, can never be recovered from the down-converted waveforms.

Tiny waveform receiver with a dedicated system chip for observing plasma waves in space

Plasma waves are important observational targets for scientific satellite missions to investigate electromagnetic phenomena that occur in space. For future scientific missions, reduction in the resource requirements of plasma wave receivers without loss of performance is important. This paper introduces a miniaturized on-board instrument for the observation of plasma waves using analogue application-specific integrated circuit (ASIC) techniques. The developed ASIC functions as a system chip to filter and amplify signals detected by plasma wave sensors. Miniaturization of the analogue circuit using the ASIC leads to the realization of a tiny plasma wave receiver. The overall size of the developed plasma wave receiver circuit board is less than 1/20 that of a conventional receiver used in previous scientific missions. The power consumptions of the system chip and the plasma wave receiver are 165 and 525 mW, respectively.

Ground-level detection of auroral kilometric radiation

[1] The Earth's auroral electrons radiate up to ∼1% of their energy in radio waves, called Auroral Kilometric Radiation (AKR). The emission mechanism, called the electron cyclotron maser (ECM), produces similar emissions at other planets, in the solar atmosphere, and possibly in astrophysical systems such as pulsars and blazars. ECM theory applied to AKR predicts radiation beamed outward that cannot penetrate near the Earth. Nevertheless, over the past several decades there have been occasional reports of AKR-like signals detected at low altitudes. Here we show the first evidence that AKR does indeed penetrate to low altitudes. For three examples of AKR-like emissions detected at South Pole Station, Antarctica, we examined data from the Geotail satellite plasma wave receiver, which had a field of view that included the auroral field lines above the station. The AKR-like emissions detected at ground-level have the same frequency-time structure as simultaneous AKR emissions detected on Geotail 115,000–190,000 km away from the Earth. These first coincident detections of AKR in space and on the ground require the existence of a mechanism to produce the ground-level emissions, suggest that previous AKR-like emissions observed at low altitudes may indeed be AKR, and require revision of the widely-held textbook view that AKR is only detectable from space.

Lunar ionosphere exploration method using auroral kilometric radiation

The evidence of a lunar ionosphere provided by radio occultation experiments performed by the Soviet spacecraft Luna 19 and 22 has been controversial for the past three decades because the observed large density is difficult to explain theoretically without magnetic shielding from the solar wind. The KAGUYA mission provided an opportunity to investigate the lunar ionosphere with another method. The natural plasma wave receiver (NPW) and waveform capture (WFC) instruments, which are subsystems of the lunar radar sounder (LRS) on board the lunar orbiter KAGUYA, frequently observe auroral kilometric radiation (AKR) propagating from the Earth. The dynamic spectra of the AKR sometimes exhibit a clear interference pattern that is caused by phase differences between direct waves and waves reflected on a lunar surface or a lunar ionosphere if it exists. It was hypothesized that the electron density profiles above the lunar surface could be evaluated by comparing the observed interference pattern with the theoretical interference patterns constructed from the profiles with ray tracing. This method provides a new approach to examining the lunar ionosphere that does not involve the conventional radio occultation technique.

Characteristics of Langmuir electric field waveforms and power spectra exhibiting nonlinear behavior in Earth's foreshock

Langmuir wave characteristics in the Earth's foreshock were examined to identify possible nonlinear wave behavior for two case studies with data from the Cluster Wideband Data Plasma Wave Receiver. The occurrence rates of four types of power spectra near the foreshock edge were determined: (1) spectra with power at the local plasma frequency fpe only, (2) spectra with power at fpe and 2fpe, (3) spectra with double peaks near fpe, and (4) spectra with double peaks near fpe and peaks at low frequencies indicative of ion acoustic waves. For electric field waveform amplitudes between 0.1 and 22.0 mV/m, most power spectra fell into the fpe only and double‐peaked categories. The maximum Langmuir wave amplitudes and bump‐on‐tail reduced electron distribution functions from Cluster PEACE data were more consistent with saturation of wave growth by electrostatic decay than modulational instabilities. However, few spectra had the double peaks near fpe and ion acoustic waves indicative of electrostatic decay, suggesting other processes may also be at work. For amplitudes greater than 22.0 mV/m, most power spectra fell into the fpe and 2fpe category, but many of the harmonics were too weak to be clearly distinguished from harmonics caused by instrumental effects.

Electrostatic solitary waves in current layers: from Cluster observations during a super-substorm to beam experiments at the LAPD

Abstract. Electrostatic Solitary Waves (ESWs) have been observed by several spacecraft in the current layers of Earth's magnetosphere since 1982. ESWs are manifested as isolated pulses (one wave period) in the high time resolution waveform data obtained on these spacecraft. They are thus nonlinear structures generated out of nonlinear instabilities and processes. We report the first observations of ESWs associated with the onset of a super-substorm that occurred on 24 August 2005 while the Cluster spacecraft were located in the magnetotail at around 18–19 RE and moving northward from the plasma sheet to the lobes. These ESWs were detected in the waveform data of the WBD plasma wave receiver on three of the Cluster spacecraft. The majority of the ESWs were detected about 5 min after the super-substorm onset during which time 1) the PEACE electron instrument detected significant field-aligned electron fluxes from a few 100 eV to 3.5 keV, 2) the EDI instrument detected bursts of field-aligned electron currents, 3) the FGM instrument detected substantial magnetic fluctuations and the presence of Alfvén waves, 4) the STAFF experiment detected broadband electric and magnetic waves, ion cyclotron waves and whistler mode waves, and 5) CIS detected nearly comparable densities of H+ and O+ ions and a large tailward H+ velocity. We compare the characteristics of the ESWs observed during this event to those created in the laboratory at the University of California-Los Angeles Plasma Device (LAPD) with an electron beam. We find that the time durations of both space and LAPD ESWs are only slightly larger than the respective local electron plasma periods, indicating that electron, and not ion, dynamics are responsible for generation of the ESWs. We have discussed possible mechanisms for generating the ESWs in space, including the beam and kinetic Buneman type instabilities and the acoustic instabilities. Future studies will examine these mechanisms in more detail using the space measurements as inputs to models, and better relate the ESW space measurements to the laboratory through PIC code models.

Furthering our understanding of electrostatic solitary waves through Cluster multispacecraft observations and theory

Nonlinear isolated electrostatic solitary waves (ESWs) are observed routinely at many of Earth’s major boundaries by the Wideband Data (WBD) plasma wave receivers that are mounted on the four Cluster satellites. The current study discusses two aspects of ESWs: their characteristics in the magnetosheath, and their propagation in the magnetosheath and in the auroral acceleration (upward current) region. The characteristics (amplitude and time duration) of ESWs detected in the magnetosheath are presented for one case in which special mutual impedance tests were conducted allowing for the determination of the density and temperature of the hot and cold electrons. These electron parameters, together with those from the ion experiment, were used as inputs to an electron acoustic soliton model as a consideration for the generation of the observed ESWs. The results from this model showed that negative potential ESWs of a few Debye lengths (10–50 m) could be generated in this plasma. Other models of ESW generation are discussed, including beam instabilities and spontaneous generation out of turbulence. The results of two types of ESW propagation (in situ and remote sensing) studies are also presented. The first involves the propagation of bipolar type ESWs from one Cluster spacecraft to another in the magnetosheath, thus obtaining the velocity and size of the solitary structures. The structures were found to be very flat, with large scale perpendicular to the magnetic field (>40 km) and small scale parallel to the field (<1 km). These results were then discussed in terms of various models which predict such flat structures to be generated. The second type of propagation study uses striated Auroral Kilometric Radiation (SAKR) bursts, observed on multiple Cluster satellites, as tracers of ion solitary waves in the upward current region. The results of all studies discussed here (pulse characteristics and ESW velocity, lifetime, and size) are compared to in situ measurements previously made on one spacecraft and to theoretical predictions for these quantities, where available. The primary conclusion drawn from the propagation studies is that the multiple spacecraft technique allows us to better assess the stability (lifetime) of ESWs, which can be as large as a few seconds, than can be achieved with single satellites.

Observations of electrostatic solitary waves associated with reconnection by Geotail and Cluster

We report the observations of Electrostatic Solitary Waves (ESWs) associated with reconnection by the Wideband Plasma Wave Receiver of Cluster and the Wave From Captures of Geotail near the diffusion region at dayside magnetopause and in the magnetotail region. ESWs have been observed along the plasma sheet boundary and near diffusion region, both earthward and tailward of the x-line. Cluster II detected the ESWs simultaneously at both side of neutral sheet by three of the four satellites. By carefully checking the data of particle, field and wave, we studied the temporal and spatial evolution of ESWs, their relative locations with reconnection layer and the relationship with the distributions of electrons. Comparison with full particle simulations with the observations, we discuss the importance of these solitary waves in collisionless reconnection and their possible generation mechanisms is provided.

Statistical behavior of foreshock Langmuir waves observed by the Cluster wideband data plasma wave receiver

Abstract. We present the statistics of Langmuir wave amplitudes in the Earth's foreshock using Cluster Wideband Data (WBD) Plasma Wave Receiver electric field waveforms from spacecraft 2, 3 and 4 on 26 March 2002. The largest amplitude Langmuir waves were observed by Cluster near the boundary between the foreshock and solar wind, in agreement with earlier studies. The characteristics of the waves were similar for all three spacecraft, suggesting that variations in foreshock structure must occur on scales greater than the 50-100km spacecraft separations. The electric field amplitude probability distributions constructed using waveforms from the Cluster WBD Plasma Wave Receiver generally followed the log-normal statistics predicted by stochastic growth theory for the event studied. Comparison with WBD receiver data from 17 February 2002, when spacecraft 4 was set in a special manual gain mode, suggests non-optimal auto-ranging of the instrument may have had some influence on the statistics.

Plasmaspheric plumes: CRRES observations of enhanced density beyond the plasmapause

CRRES plasma wave receiver density data were used to study the distribution and properties of dense plasmaspheric‐like plasma observed outside the plasmapause. Our study indicates that outer plasmaspheric structure, often called plasmaspheric plumes, blobs, tails, or detached plasma regions, can exist at all local times under all levels of geomagnetic activity. Of the 558 CRRES orbits that had at least one clearly defined plasmapause, 169 (or 30%) had plasmaspheric‐like density structures at higher L shells than the plasmapause. Most of the occurrences of plasmaspheric‐like plasma observed by CRRES were in the noon‐to‐dusk sector in the aftermath of enhanced geomagnetic activity consistent with plasmaspheric plume models.

The dependence of Langmuir wave amplitudes on position in Earth's foreshock

We present the first results of Langmuir wave observations in the foreshock from the Cluster WBD Plasma Wave Receiver. When the data were binned by distance to the foreshock boundary, the Langmuir wave amplitude probability distributions followed the log‐normal statistics predicted by stochastic growth theory for all regions of the foreshock. The Cluster data show for the first time that the centers of the probability distributions shift to lower amplitudes with increasing distance to the boundary, and that a spatially averaged power law distribution results from summing these distributions.

Solitary waves observed in the auroral zone: the Cluster multi-spacecraft perspective

Abstract. We report on recent measurements of solitary waves made by the Wideband Plasma Wave Receiver located on each of the four Cluster spacecraft at 4.5-6.5RE (well above the auroral acceleration region) as they cross field lines that map to the auroral zones. These solitary waves are observed in the Wideband data as isolated bipolar and tripolar waveforms. Examples of the two types of pulses are provided. The time durations of the majority of both types of solitary waves observed in this region range from about 0.3 up to 5ms. Their peak-to-peak amplitudes range from about 0.05 up to 20mV/m, with a few reaching up to almost 70mV/m. There is essentially no potential change across the bipolar pulses. There appears to be a small, measurable potential change, up to 0.5V, across the tripolar pulses, which is consistent with weak or hybrid double layers. A limited cross-spacecraft correlation study was carried out in order to identify the same solitary wave on more than one spacecraft. We found no convincing correlations of the bipolar solitary waves. In the two cases of possible correlation of the tripolar pulses, we found that the solitary waves are propagating at several hundred to a few thousand km/s and that they are possibly evolving (growing, decaying) as they propagate from one spacecraft to the next. Further, they have a perpendicular (to the magnetic field) width of 50km or greater and a parallel width of about 2-5km. We conclude, in general, however, that the Cluster spacecraft at separations along and perpendicular to the local magnetic field direction of tens of km and greater are too large to obtain positive correlations in this region. Looking at the macroscale of the auroral zone at 4.5-6.5RE, we find that the onsets of the broadband electrostatic noise associated with the solitary waves observed in the spectrograms of the WBD data are generally consistent with propagation of the solitary waves up the field lines (away from Earth), or with particles or waves propagating up the field line, which leads to local generation of the solitary waves all along the field lines. A discussion of the importance of these solitary waves in magnetospheric processes and their possible generation mechanisms, through electron beam instabilities and turbulence, is provided.