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 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.

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.

scholarly journals Polar and Cluster observations of a dayside inverted-V during conjunction

2007 ◽  
Vol 25 (2) ◽  
pp. 543-555 ◽  
Author(s):  
J. D. Menietti ◽  
R. A. Frahm ◽  
A. Korth ◽  
F. S. Mozer ◽  
Y. Khotyaintsev
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Large Amplitude ◽  
Field Data ◽  
Plasma Waves ◽  
Magnetic Field Data ◽  
The Magnetic Field

Abstract. We investigate particle and fields data during a conjunction of the Polar and Cluster spacecraft. This conjunction occurs near the dayside cusp boundary layer when a dayside inverted-V was observed in the particle data of both satellites. Electron, ion, electric field, and magnetic field data from each satellite confirm that the dayside inverted-V (DSIV) structure is present at the location of both satellites and the electric fields persist from the altitude of the Polar (lower) spacecraft to the altitude of the Cluster spacecraft. We observe accelerated, precipitating electrons and upward ions along the magnetic field. In addition, large amplitude electric fields perpendicular to the ambient magnetic field seen by Polar and by Cluster suggest significant parallel electric fields associated with these events. For similar DSIV events observed by the Polar spacecraft, plasma waves (identified as possible Alfvén waves) have been observed to propagate in both directions along the magnetic field line. Future conjunctions will be necessary to confirm that DSIVs are associated with reconnection sites.

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 Recent Progress in Devices Based on Magnetoelectric Composite Thin Films

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 8012
Author(s):  
Deepak Rajaram Patil ◽  
Ajeet Kumar ◽  
Jungho Ryu
Keyword(s):  
Magnetic Field ◽  
Thin Film ◽  
Electric Fields ◽  
High Frequency ◽  
Frequency Conversion ◽  
Limit Of Detection ◽  
Very High Frequency ◽  
Magnetic Field Sensors ◽  
Magnetoelectric Composite ◽  
Band Pass

The strain-driven interfacial coupling between the ferromagnetic and ferroelectric constituents of magnetoelectric (ME) composites makes them potential candidates for novel multifunctional devices. ME composites in the form of thin-film heterostructures show promising applications in miniaturized ME devices. This article reports the recent advancement in ME thin-film devices, such as highly sensitive magnetic field sensors, ME antennas, integrated tunable ME inductors, and ME band-pass filters, is discussed. (Pb1−xZrx)TiO3 (PZT), Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), Aluminium nitride (AlN), and Al1−xScxN are the most commonly used piezoelectric constituents, whereas FeGa, FeGaB, FeCo, FeCoB, and Metglas (FeCoSiB alloy) are the most commonly used magnetostrictive constituents in the thin film ME devices. The ME field sensors offer a limit of detection in the fT/Hz1/2 range at the mechanical resonance frequency. However, below resonance, different frequency conversion techniques with AC magnetic or electric fields or the delta-E effect are used. Noise floors of 1–100 pT/Hz1/2 at 1 Hz were obtained. Acoustically actuated nanomechanical ME antennas operating at a very-high frequency as well as ultra-high frequency (0.1–3 GHz) range, were introduced. The ME antennas were successfully miniaturized by a few orders smaller in size compared to the state-of-the-art conventional antennas. The designed antennas exhibit potential application in biomedical devices and wearable antennas. Integrated tunable inductors and band-pass filters tuned by electric and magnetic field with a wide operating frequency range are also discussed along with miniaturized ME energy harvesters.

Sign in / Sign up

Export Citation Format

Share Document