In the same document, Alfven explains how parallel electric fields melt the frozen-in concept:In electro-technical literature in general, the resistors and inductances in the circuit may often be non-linear and sometimes distributed over larger. Similarly, the DL symbol may mean one double layer but also a multiple double layer. We should also allow this circuit element to represent other types of E|| ; for example, mirror-produced fields. Hasegawa and Uberoi (1982) have shown that under certain conditions a hydromagnetic wave produces a magnetic field-aligned electric field, which also should be included as DL. This means that DL stands for any electric field parallel to the magnetic field. - Double Layers in Astrophysics: pg 21 Hannes Alfven 1986
DL/parallel electric field ‘structures’ are sometimes referred to as “weak double layers”, or “strong double layer”. A problem today is that DL-parallel electric field ‘structures’ are being referred to under a multitude of names such as “Time Domain Structures”, “magnetic field-aligned potentials”, “electric field structures”, “non-linear electric field structures”, “magnetic-field-aligned electric fields”, “electron holes”, “potential drops”, “space change waves”, “magnetic field holes”, “non-thermal” , "potential" etc. A internet search including any of those terms in conjunction with the space probe of your choice might yield papers on the topic of the electric field. Nonetheless, electric fields, particularly parallel electric fields, are being detected by space probes at a bevy of locations. A few such resources are herein listed and hopefully interested parties will also find more information in the reference sections of this very limited selections of papers.At that time ( - 1950) we already know enough to understand that a frozen-in treatment of the magnetosphere was absurd. But I did not understand why the frozen-in concept was not applicable. It gave me a headache for some years.
In 1963 Carl-Gunnel Falthammar and I published the second edition of Cosmical Electrodynamics together. He gave a much higher standard to the book and new results were introduced. On of them was that a non-isotropic plasma in a magnetic mirror field could produce a parallel electric field E|| the frozen-in model broke down.” - Double Layers in Astrophysics: Hannes Alfven 1986
PARKER SOLAR PROBELocalized, quasi-static parallel electric fields that are created as a result of charge separation in plasmas have been studied by scientists over the last century and have become known as double layers (DLs). DLs are important because they can efficiently accelerate charge particles, dissipate energy, and cause a local break in the frozen-in condition. As a result, they are expected to be an important process in many different types of space plasmas on Earth and on many astrophysical objects. This paper presents a brief review of the history of DLs over the last century leading to the now well-established fact that they do occur naturally in space plasmas. The paper also presents some of the latest understanding of the basic properties of DLs in the aurora region and discusses some open research questions. - The Search for Double Layers in Space Plasmas L. Andersson and R. E. Ergun
Observations by the Parker Solar Probe mission of the solar wind at about 35.7 solar radii reveal the existence of whistler wave packets with frequencies below 0.1 f/fce (20-80 Hz in the spacecraft frame). These waves often coincide with local minima of the magnetic field magnitude or with sudden deflections of the magnetic field that are called switchbacks. Their sunward propagation leads to a significant Doppler frequency downshift from 200-300 Hz to 20-80 Hz (from 0.2 f/fce to 0.5 f/fce). The polarization of these waves varies from quasi-parallel to significantly oblique with wave normal angles that are close to the resonance cone. Their peak amplitude can be as large as 2 to 4 nT. Such values represent approximately 10% of the background magnetic field, which is considerably more than what is observed at 1 a.u. Recent numerical studies show that such waves may potentially play a key role in breaking the heat flux and scattering the Strahl population of suprathermal electrons into a halo population. - Sunward propagating whistler waves collocated with localized magnetic field holes in the solar wind: Parker Solar Probe observations at 35.7 Sun radii- O.V. Agapitov, T. Dudok de Wit, F.S. Mozer, et al
VAN ALLEN PROBESOn April 5, 2019, while the Parker Solar Probe was at its 35 solar radius perihelion, the data set collected at 293 samples/sec contained more than 10,000 examples of spiky electric-field-like structures having durations less than 200 milliseconds and amplitudes greater than 10 mV/m. The vast majority of these events was caused by plasma turbulence. Defining dust events as those having similar, narrowly peaked, positive, single-ended signatures, resulted in finding 135 clear dust events, which, after correcting for the low detection efficiently, resulted in an estimate consistent with the 1000 dust events expected from other techniques. Defining time domain structures (TDS) as those having opposite polarity signals in the opposite antennas resulted in finding 238 clear TDS events which, after correcting for the detection efficiency, resulted in an estimated 500-1000 TDS events on this day. The TDS electric fields were bipolar, as expected for electron holes. Several events were found at times when the magnetic field was in the plane of the two measured components of the electric field such that the component of the electric field parallel to the magnetic field was measured. One example of significant parallel electric fields shows the negative potential that classified them as electron holes. Because the TDS observation rate was not uniform with time, it is likely that there were local regions below the spacecraft with field-aligned currents that generated the TDS. - Time domain structures and dust in the solar vicinity: Parker Solar Probe observations: F.S. Mozer, O.V. Agapitov, S.D. Bale et al
Time domain structures (TDS) (electrostatic or electromagnetic electron holes, solitary waves, double layers, etc.) are≥1 ms pulses having significant parallel (to the background magnetic field) electric fields. They are abundant through space and occur in packets of hundreds in the outer Van Allen radiation belts where they produce magnetic-field-aligned electron pitch angle distributions at energies up to a hundred keV. TDS can provide the seed electrons that are later accelerated to relativistic energies by whistlers and they also produce field-aligned electrons that may be responsible for some types of auroras. These field-aligned electron distributions result from at least three processes. The first process is parallel acceleration by Landau trapping in the TDS parallel electric field. The second process is Fermi acceleration due to reflection of electrons by the TDS. The third process is an effective and rapid pitch angle scattering resulting from electron interactions with the perpendicular and parallel electric and magnetic fields of many TDS.TDS are created by current-driven and beam-related instabilities and by whistler-related processes such as parametric decay of whistlers and nonlinear evolution from oblique whistlers. New results on the temporal relationship of TDS and particle injections, types of field-aligned electron pitch angle distributions produced by TDS, the mechanisms for generation of field-aligned distributions by TDS, the maximum energies of field-aligned electrons created by TDS in the absence of whistler mode waves, TDS generation by oblique whistlers and three-wave-parametric decay, and the correlation between TDS and auroral particle precipitation, are presented. - Time domain structures: What and where they are, what they do, and how they are made - F. S. Mozer1, O. V. Agapitov, A. Artemyev, J. F. Drake, V. Krasnoselskikh, S. Lejosne, and I. Vasko 2015
Related Van Allen Probe ArticleVan Allen Probes observations are presented which demonstrate the presence of nonlinear electric field structures in the inner terrestrial magnetosphere (<6 RE). A range of structures are observed, including phase space holes and double layers. These structures are observed over several Earth radii in radial distance and over a wide range of magnetic local times. They are observed in the dusk, midnight, and dawn sectors, with the highest concentration premidnight. Some nonlinear electric field structures are observed to coincide with dipolarizations of the magnetic field and increases in electron energy flux for energies between 1 keV and 30 keV. Nonlinear electric field structures possess isolated impulsive electric fields, often with a significant component parallel to the ambient magnetic field, providing a mechanism for nonadiabatic wave‐particle interactions in the inner magnetosphere. - Nonlinear electric field structures in the inner magnetosphere. - D. M. Malaspina L. Andersson et al
Related Van Allen Probe Landau effects:This first mechanism is based on something called time domain structures, which Mozer and his colleagues have identified previously in the belts. They are very short duration pulses of electric field that run parallel to the magnetic fields that thread through the radiation belts. These magnetic field lines guide the movement of all the charged particles in the belts: The particles move along and gyrate around the lines as if they were tracing out the shape of a spring. During this early phase, the electric pulses push the particles faster forward in the direction parallel to the magnetic fields. This mechanism can increase the energies somewhat – though not as high as traditionally thought to be needed for the Whistler waves to have any effect. However, Mozer and his team showed, through both data from the Van Allen Probes and from simulations, that Whistlers can indeed affect particles at these lower energies. - NASA’s Van Allen Probes Show How to Accelerate Electrons
Landau Affects are related to the frequency of EM waves either accelerating, “damping” (slowing down the EM wave) , resonance, and/or “trapping” charged particles.
THE ELECTRIC WIND OF VENUSSimultaneous observations of electron velocity distributions and chorus waves by the Van Allen Probe B are analyzed to identify long-lasting (more than 6 h) signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. Such Landau resonant interactions result in the trapping of ∼1–10 keV electrons and their acceleration up to 100–300 keV. This kind of process becomes important for oblique whistler mode waves having a significant electric field component along the background magnetic field. In the inhomogeneous geomagnetic field, such resonant interactions then lead to the formation of a plateau in the parallel (with respect to the geomagnetic field) velocity distribution due to trapping of electrons into the wave effective potential. We demonstrate that the electron energy corresponding to the observed plateau remains in very good agreement with the energy required for Landau resonant interaction with the simultaneously measured oblique chorus waves over 6 h and a wide range of L shells (from 4 to 6) in the outer belt. The efficient parallel acceleration modifies electron pitch angle distributions at energies ∼50–200 keV, allowing us to distinguish the energized population. The observed energy range and the density of accelerated electrons are in reasonable agreement with test particle numerical simulations. - Nonlinear local parallel acceleration of electrons through Landau trapping by oblique whistler mode waves in the outer radiation belt: O. V. Agapitov, A. V. Artemyev, D. Mourenas, F. S. Mozer, and V. Krasnoselskikh
JUPITERUnderstanding what processes govern atmospheric escape and the loss of planetary water is of paramount importance for understanding how life in the universe can exist. One mechanism thought to be important at all planets is an “ambipolar” electric field that helps ions overcome gravity. We report the discovery and first quantitative extraterrestrial measurements of such a field at the planet Venus. Unexpectedly, despite comparable gravity, we show the field to be five times stronger than in Earth's similar ionosphere. Contrary to our understanding, Venus would still lose heavy ions (including oxygen and all water‐group species) to space, even if there were no stripping by the solar wind. We therefore find that it is possible for planets to lose heavy ions to space entirely through electric forces in their ionospheres and such an “electric wind” must be considered when studying the evolution and potential habitability of any planet in any star system.
The electric wind of Venus: A global and persistent “polar wind”‐like ambipolar electric field sufficient for the direct escape of heavy ionospheric ions: Glyn A. Collinson , Rudy A. Frahm et al 2016
JUPITER - IOPrevious Juno mission event studies revealed powerful electron and ion acceleration, to 100s of kiloelectron volts and higher, at low altitudes over Jupiter's main aurora and polar cap (PC; poleward of the main aurora). Here we examine 30–1200 keV JEDI‐instrument particle data from the first 16 Juno orbits to determine how common, persistent, repeatable, and ordered these processes are. For the PC regions, we find (1) upward electron angle beams, sometimes extending to megaelectron volt energies, are persistently present in essentially all portions of the polar cap but are generated by two distinct and spatially separable processes. (2) Particle evidence for megavolt downward electrostatic potentials are observable for 80% of the polar cap crossings and over substantial fractions of the PC area. For the main aurora, with the orbit favoring the duskside, we find that (1) three distinct zones are observed that are generally arranged from lower to higher latitudes but sometimes mixed. They are designated here as the diffuse aurora (DifA), Zone‐I (ZI(D)) showing primarily downward electron acceleration, and Zone‐II (ZII(B)) showing bidirectional acceleration with the upward intensities often greater than downward intensities. (2) ZI(D) and ZII(B) sometimes (but not always) contain, respectively, downward electron inverted Vs and downward proton inverted Vs, (potentials up to 400 kV) but, otherwise, have broadband distributions. (3) Surprisingly, both ZI(D) and ZII(B) can generate equally powerful auroral emissions. It is suggested but demonstrated for intense portions of only one auroral crossing, that ZI(D) and ZII(B) are associated, respectively, with upward and downward electric currents. - Energetic Particles and Acceleration Regions Over Jupiter's Polar Cap and Main Aurora: A Broad Overview: B. H. Mauk G. Clark et al 2020 (unavailable)
Electric Currents, Magnetic field, & Electric Fields. Its seems the latter doesn't get much output in coverage so I thought it also deserves some attention!!Infrared and ultraviolet images have established that auroral emissions at Jupiter caused by the electromagnetic interaction with Io not only produce a bright spot, but an emission trail that extends in longitude from Io’s magnetic footprint. Electron acceleration that produces the bright spot is believed to be dominated by Alfve´n waves whereas we argue that the trail or wake aurora results from quasi-static parallel electric fields associated with large-scale, field-aligned currents between the Io torus and Jupiter’s ionosphere. These currents ultimately transfer angular momentum from Jupiter to the Io torus. We examine the generation and the impact of the quasi-static parallel electric fields in the Io trail aurora. A critical component to our analysis is a current-voltage relation that accounts for the low-density plasma along the magnetic flux tubes that connect the Io torus and Jupiter. This low-density region, 2 RJ from Jupiter’s center, can significantly limit the field-aligned current, essentially acting as a ‘‘high-latitude current choke.’’ Once parallel electric fields are introduced, the governing equations that couple Jupiter’s ionosphere to the Io torus become nonlinear and, while the large-scale behavior is similar to that expected with no parallel electric field, there are substantial deviations on smaller scales. The solutions, bound by properties of the Io torus and Jupiter’s ionosphere, indicate that the parallel potentials are on the order of 1 kV when constrained by peak energy fluxes of a few milliwatts per square meter. The parallel potentials that we predict are significantly lower than earlier reports. - Generation of parallel electric fields in the Jupiter–Io torus wake region: R. E. Ergun, L. Ray, P. A. Delamere, F. Bagenal,V. Dols, and Y.-J. Su 2009