Impulse Electric Field Research Articles

Surfing Acceleration of Radiation Belt Relativistic Electrons Induced by the Propagation of Interplanetary Shock

AbstractInterplanetary shocks (IPS) can initiate prompt acceleration of relativistic electrons in the Earth's radiation belt, which is related to the generation and propagation of impulsive electric field (IEF). We investigate the effect of IEF on accelerating radiation belt electrons in the 6 September 2017 IPS event. A “surfing” effect of electrons with respect to the electric field, referring to electrons that drift together with the tailward‐propagating IEF in the duskside, is investigated in this study. Our results show that the maximum increase of electron differential flux is at 3.4 MeV by a factor of 2.2, corresponding to a drift velocity of 531 km/s, which is more consistent with the IPS propagating speed of 621 km/s rather than the fast‐mode speed of 1,074 km/s. We suggest that the effect of IPS propagation is important for radiation belt dynamics, and we highlight the potential importance of the parameter of IPS propagation speed.

Ion Acceleration and Corresponding Bounce Echoes Induced by Electric Field Impulses: MMS Observations

AbstractDayside magnetosphere interactions are essential for energy and momentum transport between the solar wind and the magnetosphere. In this study, we investigate a new phenomenon within this regime. Sudden enhancements of ion fluxes followed by repeating dropouts and recoveries were observed by Magnetospheric Multiscale on 5 November 2016, which is the very end of the recovery phase from a moderate geomagnetic storm. These repetitive flux variations display energy‐dispersive characteristics with periods relevant to ion bounce motion, suggesting they are corresponding echoes. Alongside the flux variations, bipolar electric field impulses originating from external sources were detected. We traced the source region of the initial injection and found it is located near the spacecraft's position. To elucidate the underlying physics, a test‐particle simulation is conducted. The results reveal that radial transport resulting from impulse‐induced acceleration can give rise to these echoes. Observations demonstrate dayside magnetosphere interactions are more common than we previously considered, which warrants further research.

Electric-field sensor based on propylene carbonate cladding microfiber sagnac loop interferometer

Optical microfiber with diameter of wavelength scale has gained numerous successful applications in many fields, as it exhibits a number of unique characteristics and excellent optical properties such as strong confinement, physical flexibility, large evanescent fields, extreme configurability, and high robustness. In this letter, we propose a compact microfiber-based electric field sensor, which consists of a single-mode microfiber sagnac loop interferometer (SMSLI) and propylene carbonate. Owing to Kerr electro-optic effect of propylene carbonate, the refractive index (RI) of propylene carbonate cladding in the twist area of SMSLI will be changed by the applied electric field, which induces a shift of the interference pattern of SMSLI. Hence, the external electric field can be demodulated by measuring the variation of the transmission spectra of SMSLI. The feasibility of the proposed sensor is verified by detecting alternating electric field with frequency of 50 Hz and impulse electric field with duration time of 200 μs.

Temperature-Insensitive Integrated Optical Electric Field Sensor Based on Asymmetric Mach–Zehnder Interferometer

The thermal bias drift problem induces poor stability of the operating point of integrated optical electric field sensor and thus large measurement errors in the practical applications. In this article, we have proposed a passive thermal compensation approach to an inherently temperature-insensitive integrated electric field sensor. Both theoretical analysis and experiments demonstrated that the thermal bias drift could be effectively suppressed by a combination design of waveguide width and length of the asymmetric Mach–Zehnder interferometer. Based on this new waveguide design, a temperature compensated electric field sensor with optimal geometrical parameters was fabricated. Its thermal bias drift was reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-3.3^{\circ }/^{\circ }\text{C}$ </tex-math></inline-formula> to 0.23°/°C, more than ten times lower than the uncompensated conventional sensor. Furthermore, the maximum/minimum detectable electric fields are 2.5 and 200 kV/m, respectively, for measuring lighting impulse electric field, and a measurement error as low as 1.6% was achieved from 18 °C to 28 °C. These results are very encouraging for implementing practical integrated optical electric field sensing schemes.

The Dynamics of Earth’s Cusp in Response to the Interplanetary Shock

The Earth’s magnetospheric cusp, a region with an off-equatorial magnetic field minimum, is an important place which directly transports plasma and energy from the solar wind into the magnetosphere and ionosphere. Its magnetic topology and charged particles therein are known to respond to the solar wind and the interplanetary magnetic field. However, its dynamics in response to the interplanetary (IP) shock are still unknown, due to lack of direct spacecraft observations. This study first reports the observations of the cusp’s motion under the drive of an IP shock and both strong electric fields and outflowing energetic ions in the moving cusp. After an IP shock arrival on 7 September 2017, triple cusps were observed by Cluster C4 when it was crossing the high-altitude northern polar region to the sub-solar magnetosphere. The multiple cusps had a one-to-one correspondence with the dayside magnetosphere compression and relaxation detected by THEMIS E, indicating that one cusp moved back and forth three times due to the IP shock’s impact. In the moving cusp, there were strong impulsive electric fields with a peak of up to ∼40 mV/m and an ionospheric source population of upward propagating ions (O+, He+ and H+) with energies extending to MeV. However, the outflowing ions outside the cusp had energies of no more than 1 keV. An enhancement of energetic O+ appeared inside the cusp with the flux ratio of O+/H+ increasing from 10 keV to ∼ MeV, which implies the efficient acceleration of O+. These observations are shown to be consistent with the prompt acceleration by the impulsive electric fields, which is mass-dependent. This finding suggests a new acceleration mechanism for cusp energetic ions, especially for O+.

Response of Electric Field in Terrestrial Magnetosphere to Interplanetary Shock

Electric field impulses generated by interplanetary shocks can cause a series of dynamic processes in the Earth’s magnetosphere and were previously explained by either fast-mode wave propagation or flow related to compression of the magnetopause. Based on a Space Weather Modeling Framework simulation, we suggest a new scenario in which the evolution of the impulse is due to both the propagation of the fast-mode wave and the compression of the magnetopause, which can explain the simulation and observations in previous related studies. The onset of the electric field impulse is determined by the propagation of the fast-mode wave in the magnetosphere while the peak of the impulse is determined by the propagation of the compression of the magnetopause. The new understanding of the impulse is important for the generation of subsequent ultralow frequency waves through the coupling of the fast-mode to Alfvén waves and field line resonances and related radiation-belt electron acceleration.

Discharge Mechanism Difference Analysis Between Natural Ester and Mineral Oil Under Impulse Electric Field: A DFT Investigation

The lightning impulse breakdown strength of natural ester is lower than that of mineral oil. This article focuses on a discharge mechanism difference analysis of natural ester and mineral oil under a strong impulse electric field (EF). Based on density functional theory (DFT), the ionization energy, electron affinity (EA), and excitation energy of natural ester and mineral oil were calculated under different EF strengths. The microparameters related to the discharge of natural ester and mineral oil were compared, showing that the former has a lower ionization energy and a larger dipole moment. This quality makes natural ester more likely to ionize and produce electrons, which more easily promotes the formation of electron avalanches and streamer. Meanwhile, natural ester molecules are more prone to transition from the ground state to the excited state than mineral oil molecules, exacerbating the photon release and formation of discharges in natural ester. The greater conductivity of natural ester leads to its dispersion and the rapid development of discharge streamers. In addition, an electrostatic potential (ESP) analysis on molecular surfaces was used to predict the active sites of the oil molecular structure. This article provides help for understanding the relationship between the micromolecular structure and the macroscopic discharge characteristics for different types of oil molecules.

Closed-loop optimization of fast trapped-ion shuttling with sub-quanta excitation

Shuttling ions at high speed and with low motional excitation is essential for realizing fast and high-fidelity algorithms in many trapped-ion-based quantum computing architectures. Achieving such performance is challenging due to the sensitivity of an ion to electric fields and the unknown and imperfect environmental and control variables that create them. Here we implement a closed-loop optimization of the voltage waveforms that control the trajectory and axial frequency of an ion during transport in order to minimize the final motional excitation. The resulting waveforms realize fast round-trip transport of a trapped ion across multiple electrodes at speeds of 0.5 electrodes per microsecond (35 m·s−1 for a one-way transport of 210 μm in 6 μs) with a maximum of 0.36 ± 0.08 mean quanta gain. This sub-quanta gain is independent of the phase of the secular motion at the distal location, obviating the need for an electric field impulse or time delay to eliminate the coherent motion.

Influence of Broadleaved Wood Conditioning by Pulsed Electric Field on Its Combustion Heat Characteristics

This publication presents changes in sawdust of selected deciduous trees as a consequence of impulse electric field (PEF) stimulation. The analyzed changes concerned the time–temperature characteristics created during the measurement of the heat of combustion of the audited material. Based on experience from previous studies, two alternatives of electric field strength and one variant of capacitor discharges (pulses) were adopted. The results were compared with the sample not treated with PEF. The selected parameters were the result of previous studies, in which the applied variants seemed to be the most promising, i.e., they gave the most diverse results. The research presented in this work has shown that the pulsed electric field affects the time and temperature characteristics of biological material. The changes are most pronounced for the last period of the combustion process, from the moment the maximum temperature was reached to the end of the process. The obtained results indicate that birch and ash react to PEF conditioning in a similar manner. The second group, due to the similarity of the obtained results, is oak and linden. It seems that, apart from the electric field strength, the obtained results are also influenced by the cellulose content in the tested wood. The described process has a very low energy-efficiency, but the reduction of the energy needed to generate the impulse could lead to the possibility of applying the obtained results in industry.

Impulse response and electric field computation of various rod electrodes

Ionisation process has been known to occur in soil, when earth electrodes are subjected under high impulse conditions. In this paper, experimental results on impulse response of various earth electrodes, namely a conventional copper rod electrode, and three steel rods which had been in a form of solid, hollow and hollow with stamping of star shaped, is presented. Impulse tests were performed for a range of voltage magnitudes up to 300 kV. Computation of electric field is carried out with Finite Element Method (FEM) to obtain its profile, and determine the electric field values produced for each rod electrodes and peak currents. Experimental results show that little difference in its impulse resistance with increasing current magnitudes in these electrodes, which could be due to the critical electric value, Ec of the soil, and electric field of the rod electrode, which balances up its ionisation levels.

Fabrication of a High Water Flux Conductive MWCNTs/PVC Composite Membrane with Effective Electrically Enhanced Antifouling Behavior

Membrane fouling is a major issue that deteriorates the performance of membrane filtration systems. The electrically assisted membrane filtration process is proven to be effective for alleviating membrane fouling. In this study, we synthesized an electrically conductive membrane by incorporating multiwalled carbon nanotubes (MWCNTs) into polyvinyl chloride (PVC). The synthesized membranes have larger porosity than the PVC membrane (incorporating polyethylene glycol (PEG)), and thus possess much higher water flux under the same testing conditions. The initial and stable water fluxes are 2033 L/(m2·h) and 750 L/(m2·h), respectively, which are much higher than that of the pure PVC membrane. More importantly, the membrane has higher surface charge density and excellent electrical conductivity, but the surface hydrophilicity and toughness decreased with the addition of the MWCNTs. The 25 wt % MWCNTs/PVC composite membrane possesses suitable electrical conductivity of 0.128 S/m. The same membrane shows electro-enhanced antifouling performance during the antifouling test with yeast as a model foulant because the external electric field (−2 V) impulses a strong repulsion force while producing some micro bubbles to repel the foulant; thus, the membrane fouling is suppressed. In the current study, we develop a simple method to fabricate the electrically conductive membrane for application in the electrically assisted membrane filtration process.

Zero-Compression, Laminar Electron Beams From Convex Cathodes in Uniform Magnetic Fields

The need for enhanced performance of high-power RF vacuum electron devices has led to the investigation of multiple-beam, sheet beam, and annular beam configurations. A key issue with such devices is the magnetic field shaping required producing high-power, laminar beams. Field shaping is difficult when Pierce-type gun geometries are employed. The development of high current density cathodes makes the necessary beam power achievable without compression. Such cathodes can operate within a uniform magnetic field yielding advantages for both single and distributed-beam RF devices. However, the quality of the resulting beams presents problems. A project to optimize beam quality in zero-convergence electron guns was undertaken by Calabazas Creek Research, Inc. (CCR) and North Carolina State University (NCSU). The surprising result was that high-quality electron beams can be generated in uniform magnetic fields using convex (dome)-shaped cathodes. The underlying physics involves perturbation of the beam cyclotron motion by a nonadiabatic radial electric field impulse. This article examines this physical mechanism and extends the initial result to additional diode and beam geometries.

Modification of pigments content in red clover sprouts with the use of pulsed electric field

An innovative issue in food engineering is using the impulse electric field (PEF) in modeling the content of biologically active compounds in plant raw materials, including seeds. In the described experiment it was shown that it is possible to modify the carotenoid content in germinating seeds of red clover (Trifolium pratense L.) by treating the seeds with PEF before cultivation. The research material was the seeds of red clover ‘Rozeta’ variety. As a result of the conducted research, an increase in the content of lutein and zaaxanthin by 10% and β-carotene by 16% was obtained after the sprouts were subjected to a field of 5 kV/cm intensity.

Gravity Wave Generation by the Electromagnetic Field

According to the theory on the relation between the rest mass and ZPF field in the vacuum, the author shows the possibility to generate a gravitational wave by the high intensity impulsive electric field.

Relation Between Shock‐Related Impulse and Subsequent ULF Wave in the Earth's Magnetosphere

AbstractThe generation of Pc4‐5 ultralow frequency (ULF) waves after interplanetary shock‐induced electric field impulses in the Earth's magnetosphere is studied using Van Allen Probes measurements by investigating the relationship between the first impulses and subsequent resonant ULF waves. In the dayside, the relevant time scales of the first impulse is correlated better with local Alfvén speed than with local eigenfrequency, implying that the temporal scale of the first impulse is more likely related to fast‐mode wave propagation rather than local field line resonance. There are only 20 out of 51 events with narrow‐band poloidal ULF waves induced after the first impulse, showing a higher chance for ULF wave generation at the locations where the impulse equivalent frequency scale matches the local eigenfrequency. It is suggested that the shock‐related ULF wave can be excited in the magnetosphere on condition that shock‐induced impulse has large enough amplitude with its frequency matching the local eigenfrequency.

Wide range voltage-impulse-controlled nonvolatile magnetic memory in magnetoelectric heterostructure

The voltage impulse-induced large, nonvolatile, and tunable magnetization switching in a Ni80Co20/Pb(Mg, Nb)O3-PbTiO3 (PMN-PT) structure was investigated at room temperature. Ni80Co20 was deposited onto a specified PMN-PT substrate with defect dipoles. By exploiting defect dipoles, a distinct and stable strain memory state was achieved at zero electric field. It induces and sustains two distinct magnetization states when removing an electric field via the magnetoelectric coupling effect. Via the detailed x-ray diffraction and piezoresponse force microscopy analyses, the polarization switching pathway and the lattice strain in response to the in situ electric field were investigated to understand the microscopic mechanisms behind the nonvolatile magnetic memory. Furthermore, the impulse electric field can be selected in the range between the coercive field and the saturation field of the PMN-PT, leading to a wide range controlling technique. This work provides a promising way to produce a large and nonvolatile magnetic memory in magnetoelectric heterostructure and is significant for ultra-low-power information storage devices.

Penetration electric fields observed at middle and low latitudes during the 22 June 2015 geomagnetic storm

Prompt penetration electric fields were detected during the intense geomagnetic storm on 22 June, 2015 by the HF Doppler sounders at middle and low latitudes; Prague (Czech Republic), Iitate, Oarai, Onna (Japan), and Zhongli (Republic of China). The storm was initiated by the storm sudden commencement (SC) at 1833 UT, immediately followed by the main phase with the minimum SYM-H of − 139 nT at 2017 UT. The convection electric field was found to be up to 5.1 mV/m at low latitudes, which is enough to cause ionospheric disturbances such as the enhancement of the total electron content, equatorial ionization anomaly and so on. The electric fields of the SC and main phase are westward in the night (0330 MLT), while eastward in the evening (1930 MLT). The main phase electric field intensified the eastward equatorial electrojets (EEJ) at Huancayo in South America on the dayside (1330 MLT) and the westward EEJ on the nightside at Guam in the western Pacific (0330 MLT) and Tirunelveli in India (00 MLT). The eastward direction of the evening-time electric field agrees with a feature of the evening anomaly of the penetration electric field, while the intensity is suppressed because of the sunlit condition in the evening in the summer solstice. The sudden northward turning of the interplanetary magnetic field (IMF) caused a transition from the main phase to the recovery phase, when the EEJ turned into the counterelectrojet (CEJ). It was found that the HF Doppler sounders detected an impulsive eastward overshielding electric field at 2005 UT on the nightside during the northward IMF-driven CEJ with the duration of 17 min and intensity of 8.0 mV/m at Iitate (0500 MLT) and 11.8 mV/m at Prague (2130 MLT). The impulsive overshielding electric field was accompanied by the anti-sunward plasma flows at middle latitude (50°–60° GML) equatorward of the dusk sunward convection as observed with SuperDARN, which signifies intensification of the Region-2 field-aligned currents at the flow reversal. Substorm signatures are identified with intensified westward auroral electrojet and magnetic dipolarization as detected by the geosynchronous orbit satellite, ETS-VIII. Consequently, the stormtime substorm may provide strong overshielding electric fields to the middle latitude ionosphere on the nightside.

The influence of interface strain on the magnetization switching process in FeSi/(011)PMN-0.3PT heterostructures

The magnetization switching process of Fe80Si20/(PbMg1/3Nb2/3O3)0.7–(PbTiO3)0.3 (FeSi/PMN-0.3PT) heterostructures under electric-field-induced interface strain effects was investigated using the magneto-optical Kerr effect. In the as-deposited FeSi films with low four-fold magnetic anisotropy, the one-jump and two-jump loops corresponding to the 180° and 90° domain walls were observed and could be regularly tuned by applying saturated and converse electric fields in these crystalline regions. After 300 °C annealing treatment, the heterostructures presented enhanced crystallinity and interface strain effect. By applying an impulse electric field, we achieved a reliable and non-volatile two-jump and three-jump magnetization switching transition. These regulation results further confirm the magnetic anisotropy transition and magnetic energy superposition relationship in FeSi/PMN-0.3PT. The controllable magnetization switching process is significant for understanding the mechanism of magnetic anisotropy competition and for designing the relevant magnetoelectric devices.

Simulation of Prompt Acceleration of Radiation Belt Electrons During the 16 July 2017 Storm

AbstractWe investigate the prompt enhancement of radiation belt electron flux observed by the Relativistic Electron Proton Telescope instrument on board Van Allen Probes following the 16 July 2017 CME‐shock compression using MHD‐test particle simulations. The prompt enhancements can be explained by the source population interacting with the azimuthally directed electric field impulses induced by CME‐shock compressions of the dayside magnetopause. Electrons in drift resonance with the electric field impulse were accelerated by ∼ 0.6 MeV on a drift period timescale (in minutes) as the impulse propagated from the dayside to the nightside around the flanks of the magnetosphere. MHD test particle simulation of energization and drift phase bunching, due to the bipolar electric field that accompanies the dayside compression and relaxation, is found to be consistent with Van Allen Probes observations. This study reproduces the energy‐dependent drift echoes integrated over pitch angle and observed change in spectra for the first time.

The use of impulse electric and magnetic fields in obtaining permanent joints

The article discusses the possibility of using electromagnetic influence in the production of permanent compounds such as metal–ceramics, metal–glass, as well as composite compounds from powder materials. It is proposed to use magnetic pulse action to form such joints in the solid phase: in the atmosphere with the position of parts at an angle; in vacuum with preheating and subsequent radial action. When consolidating powder materials (sintering with simultaneous pressing), a scheme of synchronous action of electromagnetic energy is proposed: thermal and mechanical.