scholarly journals Solar Orbiter/Radio and Plasma Wave observations during the first Venus flyby

2021 ◽  
Author(s):  
Niklas J. T. Edberg ◽  
Lina Hadid ◽  
Milan Maksimovic ◽  
Stuart D. Bale ◽  
Thomas Chust ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Wave ◽  
Electric Fields ◽  
High Frequency ◽  
Dynamic Environment ◽  
Power Spectra ◽  
Bow Shock ◽  
Double Layers ◽  
Tail Region ◽  
Electric And Magnetic Field

<p>We present measurements from the Radio and Plasma Wave (RPW) instrument suite onboard the Solar Orbiter mission during the first Venus encounter. RPW consists of several units and is capable of measuring both the electric and magnetic field fluctuations with three electric antennas and a search-coil magnetometer: The Low Frequency Receiver (LFR) cover the range from DC up to 10kHz when measuring the electric and magnetic waveform and spectra; the Thermal Noise and High Frequency Receiver (TNR-HFR) determines the electric power spectra and magnetic power spectra from 4kHz-20MHz, and 4kHz to 500kHz, respectively, to determine properties of the electron population; the Time Domain Sampler (TDS) measures and digitizes onboard the electric and magnetic field waveforms from 100 Hz to 250 kHz. The BIAS subunit measures DC and LF electric fields as well as the spacecraft potential, which gives a high cadence measure of the local plasma density when calibrated to the low-cadence tracking of the plasma peak from the TNR. Solar Orbiter approached Venus from the induced magnetotail and had its closest approach at an altitude of 7500 km over the north pole of Venus on 27 Dec 2020. The RPW instruments observed a tail region that extended several 10’s of Venus radii downstream of the planet. The induced magnetosphere was characterized to be a highly dynamic environment as Solar Orbiter traversed the downstream tail and magnetosheath before it crossed the Bow Shock outbound at ~12:40 UT. Polarized whistler waves, high frequency electrostatic waves, narrow-banded emissions, possible electron double layers were observed. The fine structure of the bow shock could also be investigated in detail. Solar Orbiter could hence enhance the knowledge of the structure of the solar wind-Venus interaction.</p>

scholarly journals Double layers in the downward current region of the aurora

2003 ◽  
Vol 10 (1/2) ◽  
pp. 45-52 ◽  
Author(s):  
R. E. Ergun ◽  
L. Andersson ◽  
C. W. Carlson ◽  
D. L. Newman ◽  
M. V. Goldman
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Double Layers ◽  
Parallel Electric Field ◽  
Electrostatic Waves ◽  
Current Region ◽  
Decisive Evidence

Abstract. Direct observations of magnetic-field-aligned (parallel) electric fields in the downward current region of the aurora provide decisive evidence of naturally occurring double layers. We report measurements of parallel electric fields, electron fluxes and ion fluxes related to double layers that are responsible for particle acceleration. The observations suggest that parallel electric fields organize into a structure of three distinct, narrowly-confined regions along the magnetic field (B). In the "ramp" region, the measured parallel electric field forms a nearly-monotonic potential ramp that is localized to ~ 10 Debye lengths along B. The ramp is moving parallel to B at the ion acoustic speed (vs) and in the same direction as the accelerated electrons. On the high-potential side of the ramp, in the "beam" region, an unstable electron beam is seen for roughly another 10 Debye lengths along B. The electron beam is rapidly stabilized by intense electrostatic waves and nonlinear structures interpreted as electron phase-space holes. The "wave" region is physically separated from the ramp by the beam region. Numerical simulations reproduce a similar ramp structure, beam region, electrostatic turbulence region and plasma characteristics as seen in the observations. These results suggest that large double layers can account for the parallel electric field in the downward current region and that intense electrostatic turbulence rapidly stabilizes the accelerated electron distributions. These results also demonstrate that parallel electric fields are directly associated with the generation of large-amplitude electron phase-space holes and plasma waves.

scholarly journals Electric fields and double layers in plasmas

1987 ◽  
Vol 5 (2) ◽  
pp. 233-255 ◽  
Author(s):  
Nagendra Singh ◽  
H. Thiemann ◽  
R. W. Schunk
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Electric Fields ◽  
Sheet Thickness ◽  
High Density ◽  
Effective Length ◽  
Double Layers ◽  
Low Density ◽  
Ambient Magnetic Field ◽  
Cold Plasmas

Various mechanisms for driving double layers in plasmas are briefly described, including applied potential drops, currents, contact potentials, and plasma expansions. Some dynamic features of the double layers are discussed. These features, as seen in simulations, laboratory experiments and theory, indicate that double layers and the currents through them undergo slow oscillations, which are determined by the ion transit time across an effective length of the system in which the double layers form. It is shown that a localized potential dip forms at the low potential end of a double layer, which interrupts the electron current through it according to the Langmuir criterion, whenever the ion flux into the double is disrupted. The generation of electric fields perpendicular to the ambient magnetic field by contact potentials is also discussed. Two different situations have been considered; in one, a low-density hot plasma is sandwiched between high-density cold plasmas, while in the other a high-density current sheet permeates a low-density background plasma. Perpendicular electric fields develop near the contact surfaces. In the case of the current sheet, the creation of parallel electric fields and the formation of double layers are also discussed when the current sheet thickness is varied. Finally, the generation of electric fields (parallel to an ambient magnetic field) and double layers in an expanding plasma are discussed.

scholarly journals Solar Orbiter’s first Venus Flyby: MAG observations of structures and waves associated with the induced Venusian magnetosphere

2021 ◽  
Author(s):  
Martin Volwerk ◽  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
High Frequency ◽  
Cyclotron Frequency ◽  
Plasma Waves ◽  
Bow Shock ◽  
High Frequency Plasma ◽  
Frequency Plasma ◽  
Mirror Mode ◽  
Proton Cyclotron

<p>The induced magnetosphere of Venus is created by the interaction of the solar wind and embedded interplanetary magnetic field with the exosphere and ionosphere of Venus. Solar Orbiter entered Venus’s magnetotail far downstream, > 70 Venus radii, of the planet and exited the magnetosphere over the north pole. This offered a unique view of the system over distances that were only flown through once by three other missions before, Mariner 10, Galileo and Bepi-Colombo. The large-scale structure and activity of the induced magnetosphere is studied as well as the high-frequency plasma waves both in the magnetosphere and in a limited region upstream of the planet where interaction with Venus’s exosphere is expected.  It is shown that Venus’s magnetotail is very active during the Solar Orbiter flyby. Structures such as flux ropes, and reconnection sites are encountered as well as a strongly overdraping of the magnetic field downstream of the bow shock and planet. High-frequency plasma waves (up to 6 times the local proton cyclotron frequency) are observed in the magnetotail, which are identified as Doppler-shifted proton cyclotron waves, whereas in the upstream solar wind these waves appear just below the proton cyclotron frequency (as expected) but are very patchy. The bow shock is quasi perpendicular, however, expected mirror mode activity is not found directly behind it; instead there is strong cyclotron wave power. This is most-likely caused by the relatively low plasma-beta  behind the bow shock. Much further downstream in the magnetosheath mirror mode of magnetic hole structures are identified. This presentation will take place after the second Venus flyby by Solar Orbiter and BepiColombo and Solar Orbiter on 9 and 10 August, respectively.</p>

scholarly journals Controlled Phase Interactions Between Pulsed Electric Fields, Ultrasonic Motion, and Magnetic Fields in an Anodic Dissolution Cell

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Curtis Bradley ◽  
Johnson Samuel
Keyword(s):  
Magnetic Field ◽  
Anodic Dissolution ◽  
Electric Fields ◽  
High Frequency ◽  
Performance Metrics ◽  
Removal Rate ◽  
Ultrasonic Transducer ◽  
Three Dimensional ◽  
Electrochemical Machining ◽  
3D Printed

This paper presents the design of a novel testbed that effectively combines pulsed electric field waveforms, ultrasonic velocity, and magnetic field waveforms in an anodic dissolution electrochemical machining (ECM) cell. The testbed consists of a custom three-dimensional (3D)-printed flow cell that is integrated with (i) a bipolar-pulsed ECM circuit, (ii) an ultrasonic transducer, and (iii) a custom-built high-frequency electromagnet. The driving voltages of the ultrasonic transducer and electromagnet are calibrated to achieve a timed workpiece velocity and magnetic field, respectively, in the machining area. The ECM studies conducted using this testbed reveal that phase-controlled waveform interactions between the three assistances affect both the material removal rate (MRR) and surface roughness (Ra) performance metrics. The triad-assisted ECM case involving phase-specific combinations of all three high-frequency (15.625 kHz) assistance waveforms is found to be capable of achieving a 52% increase in MRR while also simultaneously yielding a 78% improvement in the Ra value over the baseline pulsed-ECM case. This result is encouraging because assisted ECM processes reported in the literature typically improve only one of these performance metrics at the expense of the other. In general, the findings reported in this paper are expected to enable the realization of multifield assisted ECM testbeds using phase-specific input waveforms that change on-the-fly to yield preferential combinations of MRR and surface finish.

Characterization of interactive force acting on colloidal particles near an electrode in presence of a high-frequency (>10 kHz) AC electric field using particle diffusometry

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Kshitiz Gupta ◽  
Dong Hoon Lee ◽  
Steven T. Wereley ◽  
Stuart J. Williams
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Particle Motion ◽  
Electrode Surface ◽  
High Frequency ◽  
Colloidal Particles ◽  
Low Frequency ◽  
Double Layers ◽  
Average Height ◽  
Ac Electric Field

Colloidal particles like polystyrene beads and metallic micro and nanoparticles are known to assemble in crystal-like structures near an electrode surface under both DC and AC electric fields. Various studies have shown that this self-assembly is governed by a balance between an attractive electrohydrodynamic (EHD) force and an induced dipole-dipole repulsion (Trau et al., 1997). The EHD force originates from electrolyte flow caused by interaction between the electric field and the polarized double layers of both the particles and the electrode surface. The particles are found to either aggregate or repel from each other on application of electric field depending on the mobility of the ions in the electrolyte (Woehl et al., 2014). The particle motion in the electrode plane is studied well under various conditions however, not as many references are available in the literature that discuss the effects of the AC electric field on their out-of-plane motion, especially at high frequencies (>10 kHz). Haughey and Earnshaw (1998), and Fagan et al. (2005) have studied the particle motion perpendicular to the electrode plane and their average height from the electrode mostly in presence of DC or low frequency AC (<1 kHz) electric field. However, these studies do not provide enough insight towards the effects of high frequency (>10 kHz) electric field on the particles’ motion perpendicular to the electrode plane.  

Parametric Instability of Plasma Waves in a Magnetic Field, Due to High-Frequency Electric Fields

1972 ◽  
Vol 28 (4) ◽  
pp. 206-209 ◽  
Author(s):  
R. P. H. Chang ◽  
M. Porkolab ◽  
B. Grek
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
High Frequency ◽  
Parametric Instability ◽  
Plasma Waves

scholarly journals An Analogy Between the Effects of Fluctuating Electric Fields and Steady Magnetic Fields in Isotropic Conductors when a Universal Relaxation Time Cannot Be Defined

1960 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
EJ Moore
Keyword(s):  
Magnetic Field ◽  
Relaxation Time ◽  
Electric Field ◽  
Electric Fields ◽  
High Frequency ◽  
Present Note ◽  
Isotropic Solid ◽  
High Frequency Electric Field ◽  
Circular Frequency ◽  
Steady Magnetic Field

It is well known that when a " universal" time of relaxation ("t') exists, the influence of a harmonically varying electric field (F cceiOlt) on the transport properties of a solid may be taken into account by replacing "t' by "t'/(l +iCil"t'). Dingle (1956a) demonstrated that, for an isotropic solid, the effect of a steady magnetic field may similarly be obtained by replacing "t' by "t'/(l+j~l"t') with an applied d;c. electric field, and by "t'/[l+(iCil+jO)"t'] with an a.c. field. (Here j2= -1, ij -=1= -1, and 0=( -e)H/mc is the circular frequency of precession of an electron.) The object of the present note is to show that this analogy between a high frequency electric field and a steady magnetic field still exists, even when a " universal" relaxation time cannot be defined.

High frequency energy radiation of n-type semiconductors at constant electric and magnetic field

2013 ◽  
Vol 7 ◽  
pp. 1035-1042
Author(s):  
Eladar Rasuloglu Hasanov ◽  
Akber Zeynalabdin Panahov ◽  
Ali Ihsan Demirel
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Energy Radiation ◽  
Electric And Magnetic Field

scholarly journals MHD Turbulence in the Solar Wind and Interplanetary Dynamo Effects

1993 ◽  
Vol 157 ◽  
pp. 51-57
Author(s):  
E. Marsch ◽  
C.-Y. Tu
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Electric Fields ◽  
Power Spectra ◽  
Dynamo Theory ◽  
Mhd Turbulence ◽  
Correlation Studies ◽  
Negative Results ◽  
Alpha Effect ◽  
The Mean

From the fluctuations of the velocity and magnetic field observed in different kinds of solar wind the fluctuating electric fields are derived, and their power spectra are constructed and analysed. The mean electromotive force ɛ generated by the turbulent motions depends upon the nature of the fluctuations. Simple dynamo theory predicts a linear relationship between ɛ and the mean magnetic field B0. Correlation studies carried out to establish the alpha effect in the solar wind have given negative results.

High time resolution plasma wave and magnetic field observations of the Jovian bow shock

1985 ◽  
Vol 12 (4) ◽  
pp. 183-186 ◽  
Author(s):  
S. L. Moses ◽  
F. V. Coroniti ◽  
C. F. Kennel ◽  
F. L. Scarf ◽  
E. W. Greenstadt ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Wave ◽  
Time Resolution ◽  
Bow Shock ◽  
High Time ◽  
High Time Resolution ◽  
Field Observations
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