Electric Field Ez Research Articles

Influence of the electric field perpendicular to the current sheet on ion beamlets in the magnetotail

Several studies, both experimental, analytical, and numerical, show that a substantial electrostatic field Ez perpendicular to the magnetotail current sheet can be found. This electric field has a typical bipolar structure. We propose a theoretical analysis describing the ion behavior in the vicinity of the current sheet under the influence of Ez in a two‐dimensional taillike magnetic field reversal. It is shown that for some initial parameters resonant acceleration is possible, forming beamlets (small‐scale and almost monoenergetic field‐aligned ion beams). To check the analytical results, a test particle simulation has been performed, where the dawn‐dusk electric field Ey is also present to accelerate particles. We find that for electric field Ez pointing away (or toward) the current sheet, the beamlet resonant regions are shifted toward the Earth (or away from the Earth) resulting in decreasing (or increasing) typical energy of ions leading to the modification of the universal scaling predicted by Zelenyi et al. (2007). Another effect due to the presence of Ez is an overlapping of beamlet energies to form a wide energetic beam. Implications for beamlet observations are discussed.

Morning polar substorms and variations in the atmospheric electric field

The effects of morning magnetospheric substorms in the variations in near-Earth atmospheric electricity according to the observations of the electric field vertical component (Ez), at Hornsund polar observatory (Spitsbergen). The Ez, data, obtained under the conditions of fair weather (i.e., in the absence of a strong wind, precipitation, and fog), are analyzed. An analysis of the observations indicated that the development of a magnetospheric substorm in the Earth’s morning sector is as a rule accompanied by positive deviations in Ez, independently of the Hornsund location: in the polar cap or at its boundary. In all considered events, Hornsund was located near the center of the morning convection vortex. In the evening sector, when Hornsund fell in the region of evening convection vortex, the development of a geomagnetic substorm was accompanied by negative deviations in Ez., It has been concluded that the variations in the atmospheric electric field Ez), at polar latitudes, observed during the development of magnetospheric substorms, result from the penetration of electric fields of polar ionospheric convection (which are intensified during a substorm) to the Earth’s surface.

Effect of magnetic storms in variations in the atmospheric electric field at midlatitudes

The observations of the variations in the vertical component of the atmospheric electric field (E z ) at Swider midlatitude Poland observatory (geomagnetic latitude 47.8°) under the conditions of fair weather during 14 magnetic storms have been analyzed. The effect of the magnetic storm main phase in the daytime midlatitude variations in E z in the absence of local geomagnetic disturbances has been detected for the first time. Considerable (∼100–300 V m−1) decreases in the electric field strength (E z ) at Swider observatory were observed in daytime simultaneously with the substorm onset in the nighttime sector of auroral latitudes (College observatory). The detected effects indicate that an intensification of the interplanetary electric field during the magnetic storm main phase, the development of magnetospheric substorms, and precipitation of energetic electrons into the nighttime auroral ionosphere can result in considerable disturbances in the midlatitude atmospheric electric field.

Influence of strike object grounding on close lightning electric fields

Using the finite difference time domain (FDTD) method, we have calculated vertical electric field Ez, horizontal (radial) electric field Eh, and azimuthal magnetic field Hϕ produced on the ground surface by lightning strikes to 160‐m‐ and a 553‐m‐high conical strike objects representing the Peissenberg tower (Germany) and the CN Tower (Canada), respectively. The fields were computed for a typical subsequent stroke at distances d′ from the bottom of the object ranging from 5 to 100 m for the 160‐m tower and from 10 to 300 m for the 553‐m tower. Grounding of the 160‐m object was assumed to be accomplished by its underground basement represented by a 10‐m‐radius and 8‐m‐long perfectly conducting cylinder with or without a reference ground plane located 2 m below. The reference ground plane simulates, to some extent, a higher‐conducting ground layer that is expected to exist below the water table. The configuration without reference ground plane actually means that this plane is present, but is located at an infinitely large depth. Grounding of the 553‐m object was modeled in a similar manner but in the absence of reference ground plane only. In all cases considered, waveforms of Eh and Hϕ are not much influenced by the presence of strike object, while waveforms of Ez are. Waveforms of Ez are essentially unipolar (as they are in the absence of strike object) when the ground conductivity σ is 10 mS/m (the equivalent transient grounding impedance is several ohms) or greater. Thus, for the CN Tower, for which σ ≥ 10 mS/m, the occurrence of Ez polarity change is highly unlikely. For the 160‐m tower and for σ = 1 and 0.1 mS/m, waveforms of Ez become bipolar (exhibit polarity change) at d′ ≤ 10 m and d′ ≤ 50 m, respectively, regardless of the presence of the reference ground plane. The corresponding equivalent transient grounding impedances are about 30 and 50 Ω in the absence of the reference ground plane and smaller than 10 Ω in the presence of the reference ground plane. The source of opposite polarity Ez is the potential rise at the object base (at the air/ground interface) relative to the reference ground plane. For a given grounding electrode geometry, the strength of this source increases with decreasing σ, provided that the grounding impedance is linear. Potential rises at the strike object base for σ = 1 and 0.1 mS/m are some hundreds of kilovolts, which is sufficient to produce electrical breakdown from relatively sharp edges of the basement over a distance of several meters (or more) along the ground surface. The resultant ground surface arcs will serve to reduce the equivalent grounding impedance and, hence, potential rise. Therefore, the polarity change of Ez near the Peissenberg tower, for which σ is probably about 1 mS/m, should be a rare phenomenon, if it occurs at all. The equivalent transient grounding impedance of the cylindrical basement is similar to that of a hemispherical grounding electrode of the same radius. For the 160‐m tower and for hemispherical grounding electrode, the transient grounding impedance is higher than its dc grounding resistance for σ = 10 and 1 mS/m, but lower for σ = 0.1 mS/m. For the 553‐m tower, the transient grounding impedance of hemispherical electrode is equal to or larger than its dc resistance for all values of σ considered.

Surface‐Driven Asymmetry and Instability in the Acceleration Region of Hall Thruster

AbstractIt has been shown experimentally that the channel wall material has a substantial effect on the behaviour of Hall discharges. For this reason, the radial profile inside the Hall thruster SPT‐100 is investigated in detail. This is done by a one‐dimensional fully kinetic self‐consistent Particle‐in‐Cell model between the two walls in the acceleration region of the channel. A detailed Monte Carlo probabilistic model for secondary electron emission is implemented as boundary module. Using the local field approximation, two different operative conditions (axial electric field Ez =100 V/cm and 300 V/cm) have been simulated. For high discharge voltage case, a strong radial asymmetry and a stream instability propagating all along the radial domain are detected, while in the low voltage case a stable classical situation is recovered. The critical parameters for triggering this unstable regime are the electron azimuthal drift energy and the induced secondary electron emission, while the saturation mechanism is the increasing of the temperature of the initially cold secondary‐electrons. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Coherence of terahertz emission from photoexcited electron-hole plasma: Hydrodynamic model and Monte Carlo simulations

Terahertz emission from the electron-hole plasma excited by the femtosecond laser pulse in semiconductor structures is analyzed. It is shown that plasma excitations in the homogeneous structures are incoherent. The incoherence of the excitations essentially reduces the intensity of terahertz radiation. The -doped heterostruc- ture for coherent plasma excitations is suggested. The Monte Carlo simulations show that the efficiency of terahertz emission from the suggested structure exceeds the efficiency of terahertz emission from semiconduc- tor surface and from p-i-n structures by 2 orders of magnitude. Our analysis of the transient dynamics of photoexcited carriers shows that the surface and contactless p-i-n terahertz emitters have serious deficiencies that significantly reduce the intensity of terahertz radiation. First, only a minor part of the excited carriers contributes to the transient current if the inverse absorption coefficient exceeds the surface depletion width or the i layer thickness of the p-i-n structure. In this case, the major part of carriers is created in the region where the built-in electric field is screened by the extrinsic carriers. Second, the plasma frequency of the excited carriers is posi- tion dependent due to the exponential decay of the created carrier density. As a result, the transient response of the cre- ated carriers is incoherent in different regions of the structure because the frequency of current oscillations is position de- pendent. Therefore, the amplitude of oscillations of the re- sulting conductivity current is significantly reduced by the interference effects. In this work, we show that terahertz en- ergy radiated from the contactless structures is significantly enhanced when such deficiencies are eliminated. The -doped p-i-n heterostructure for the efficient terahertz gen- eration is suggested. The transient dynamics of photoexcited carriers is analyzed by using the hydrodynamic model and the ensemble Monte Carlo EMC simulations. The EMC simulations of the transient dynamics of photo- excited carriers are performed following Ref. 6. The models of GaAs and AlGaAs are taken from Ref. 9. The multichan- nel intercarrier scattering, the Pauli exclusion principle, and the photoexcitation of electron-hole pairs are considered. 6 The central photon energy 0 is taken to be 1.55 eV. The full width at half maximum F of the Gaussian optical pulse in- tensity is set to 100 fs. The exponential spatial profile of the density of photoexcited carriers is considered. The carrier thermionic emission over the potential barriers of heterojunc- tions and the tunneling through the barriers are taken into account. The triangular and trapezoidal shapes of the poten- tial barriers are considered for the carrier tunneling. 9 To investigate the role of the incoherence of plasma exci- tations, we consider the contactless GaAs p-i-n structure. 5,6 We use the hydrodynamic approach for the nonlinear analy- sis of the transient dynamics of photoexcited carriers taking into account the spatially nonuniform photoexcitation. The dynamics of the excited electron-hole plasma in the contact- less p-i-n structure is analyzed under the following simplify- ing assumptions. Let us assume that carriers are instantly generated, i.e., the intensity of the optical excitation fluence It can be approximated as It=I0t. This assumption is valid if the condition Ff1 is satisfied, where f is the fre- quency of plasma oscillations. Because the net current of the conductivity and displacement currents is equal to zero in the contactless structure, the spatiotemporal variations of the electric field Ez,t, electron and hole average velocities vez,t and vhz,t, and electron and hole densities nz,t and pz,t obey the equation

Beam extraction from a Hall-type ion accelerator

Fundamental characteristics of beam extraction from a Hall-type accelerator working with permanent magnets were investigated. Ions were extracted by an axial electric field E(z) in a small annular plasma channel with a radial magnetic field B(r). Effects of discharge current and voltage, length of discharge channel, and gas flow rate were examined. It can deliver a large beam current density of more than 100 mA/cm(2) with low beam energy of 50 eV. By biasing an additional plasma chamber attached at the extraction area, the beam energy was controlled independently of the beam current.

Electromagnetic Fields at the Top of a Tall Building Associated With Nearby Lightning Return Strokes

We have calculated, using the finite-difference time-domain (FDTD) method for solving Maxwell's equations, the vertical electric field Ez and azimuthal magnetic field Hphi due to lightning return strokes in the presence and in the absence of a building at the field point. Strikes to both flat ground and tall objects of height h = 100, 200, or 500 m are considered. The magnitude of Hphi is not much influenced by the presence of either building at the field point or strike object, while the magnitude of Ez is significantly influenced by either of them. In the case of a lightning strike to flat ground, the magnitude of Ez at the top of the building (at the center point of its flat roof) of plan area Sb = 40 times 40 m2 and height hb = 20, 50, or 100 m located at horizontal distance ranging from 100 to 500 m from the lightning channel is about 1.5, 2, or 3 times, respectively, greater than that at the same horizontal distance on the ground surface in the absence of the building. The enhancement factor for lightning (transient) Ez due to the presence of the building at the field point is essentially not influenced by the presence of the strike object (up to 500 m in height) and is similar to the static electric field enhancement factor due to the presence of the same building in a uniform vertical electric field. The magnitude of the electric field at the corner of the building is about two to three times larger than that at the center point of its flat roof. The magnitude of Ez at the ground level in the immediate vicinity of the building is reduced relative to the case of no building, with this shielding effect becoming negligible at horizontal distances from the building exceeding twice the height of the building.

Horizontal structure of the electric field in the stratiform region of an Oklahoma mesoscale convective system

This analysis combines vertical electric field components Ez observed by two research aircraft flying horizontally at two levels, with vertical soundings of thermodynamic parameters and Ez made by five balloons, to produce a quasi‐three‐dimensional view of the space charge distribution in the trailing stratiform cloud region behind a mesoscale convective system (MCS) that developed in central Oklahoma late in the afternoon of 2 June 1991. The balloons were launched serially at one‐hour intervals from two sites separated by 80 km along a north‐south line as the MCS moved eastward, yielding two east‐west time‐height cross‐sections of the Ez structure within the quasi‐steady state trailing stratiform region behind the MCS. The balloon measurements are consistent with a vertical stack of five rearward‐ and downward‐sloping horizontal sheets of charge of alternating polarity, beginning at the bottom with a negative charge layer below the 0°C level and a positive layer near the 0°C level. This structure persisted for more than 2 hours. The two aircraft flew back and forth along a north‐south line through the balloon launch sites during the balloon launch period. Aircraft measurements demonstrated that the vertical electric field (Ez) at constant altitude varied in the north‐south direction. The peak magnitudes of Ez deduced from the airborne instrument systems agreed with the magnitudes deduced from the balloon measurements at the aircraft altitudes of 4.5 km and 5.8 km AGL. Rapid reversals in polarity of Ez with peak magnitude >50 kV m−1 observed by the aircraft at 4.5 km, just above the 0°C level, confirms the thin concentrated positive charge layer observed there by balloons and suggests that this charge layer is undulating above and below 4.5 km altitude, at least in the north‐south direction. Microphysically, this layer contained large aggregates and pockets of low cloud liquid water concentration. At the 5.8 km level, the polarity of Ez was always positive but the magnitude varied from zero to 25 kV m−1. Aircraft‐observed Ez at both altitudes varied on horizontal scales of ∼10 km or greater at both levels, suggesting that the charge density derived using the one‐dimensional infinite‐layer Gauss's law approximation applied to the balloon soundings of Ez is valid in this study. These observations show that layers of charge can persist for hours as they advect rearward in a storm‐relative sense, possibly due to continuing in situ charge separation, and/or due to weak dispersion, slow recombination and slow settling of charge attached to low mobility low terminal velocity ice hydrometeors.

South Pole electric field responses to overhead ionospheric convection

Measurements of the vertical atmospheric electric field (Ez) at the South Pole between 1982 and 1986 have been analyzed, and the results reveal an important component due to magnetospheric‐ionospheric coupling processes. The results are consistent with the theoretical expectation that the ionospheric convection potential patterns in the polar caps, as measured by satellites, are superimposed on the otherwise nearly uniform (but varying in time) global ionospheric potential due to low‐latitude thunderstorm sources. The analysis technique was to calculate the ionospheric convection potential from a satellite empirical model, using as input measured solar wind parameters, except that when solar wind data were not available we used as inputs measured ground based magnetic disturbance parameters. We fitted the average low‐latitude Ez variation (the Carnegie curve) to the individually measured South Pole Ez diurnal curves. We then subtracted the fitted Carnegie curves from the measured curves and performed a regression analysis of the residual on the calculated ionospheric convection potential values, averaging the data in three hour intervals. Positive correlations with correlation coefficients of about 0.5 were found. Most of the remaining variability in Ez can be attributed to local meteorologically induced noise (especially in winter) and the day‐to‐day variability of the low‐latitude thunderstorm generators.

Formating double layer mechanism by electric charged particle stream in plasma

In this paper, two-fluid equations have been solved after having considered magnetic field generated by charged particle stream. Finally, the distribution of electric field Ez(z, r) and its growth rate γ in plasma have been obtained. From the expression of Ez(z, r) it can be known that the double layer has been formed. With the increase of disturbance γ will be larger, and finally this will result in the interruption of electric current and occurrence of burst.

Two‐dimensional HaIl‐MHD simulation of current sheet dynamics during substorm growth phase

In this paper we study the dynamical evolution of the current sheet in the near‐Earth geomagnetic tail region during the substorm growth phase by means of HaIl‐MHD simulation. Special attention is paid to the development of cross‐tail electric current components attributed to the electrons and ions. It is found that the induced component of the electric field generated during the current sheet thinning process leads to E×B drift of both the electrons and ions toward the dawnward direction, which augments the electron diamagnetic drift but opposes the ion diamagnetic drift. This effect causes the electrons to carry a higher and higher portion of the cross‐tail current as time progresses, even if the bulk of the initial current may be carried by the ions. However, the,increase of electron current strongly depends on the boundary condition and on the location along the distant‐tail/near‐Earth axis. It is found that close to the near‐Earth simulation boundary, a sizable normal magnetic field component Bz persists even in the late phase of the simulation. This limits the north‐south electric field Ez to a relatively low value, and as a result, the cross‐tail current is largely carried by the ions there. However, toward the distant tail, Bz is much weaker, and thus the electron current is seen to increase quite rapidly.

Self-consistent equilibria in a cylindrical reversed-field pinch

A previous investigation by one of us, concerning the self-consistent equilibria of a two-region (plasma+gas) cylindrical Tokamak, is extended to the similar equilibria of a Reversed-Field Pinch, where a significant current density is driven by a dynamo electric field due to turbulence. The previous model has been generalized under the following basic assumptions:a) to the lowest order, the turbulent dynamo electric fieldEt is expressed as a homogeneous function of degree 1 of the magnetic fieldB, sayEt=α·B, with α being a 2nd-rank tensor, homogeneous of degree 0 inB, and generally depending on the plasma state;b)Et does not appear in the plasma power balance, as if it were produced by a Maxwell demon able to extract the needed power from the plasma internal energy. In particular we show that, in the simplest case when both α and the plasma resistivity η are isotropic and constant, the magnetic field turns out force-free with constant abnormality αμ0/η for vanishing axial electric fieldEz. This case has also been solved analytically, for whateverEz, under circular, besides cylindrical, symmetry.

Formation of thin current sheets during plasma sheet convection

Fully kinetic simulations in two spatial dimensions are used to demonstrate that the attempt to establish convection in the near‐Earth magnetotail can drive the cusp or hinge region to form a thin current sheet which is embedded within a thicker plasma sheet. The simulation model incorporates a realistic near‐Earth magnetic field configuration including dipolelike and taillike regions and allows plasma to precipitate at the earthward boundary. The imposition of an electrostatic convection field leads to a slow earthward convection of plasma and a tailward transfer of magnetic flux, with the inductive electric field opposing and almost canceling the external field. This flux transfer leads to the formation of a deep minimum in the equatorial Bz field in the near‐Earth plasma sheet. As a consequence of the difference in dynamics between electrons and ions, the central plasma sheet in the cusp region becomes negatively charged, which leads to the formation of a strong polarization electric field (Ez). The growth of the polarization field causes the electrons to carry the dominant current in the thin current sheet, whose characteristic half thickness is of the order of the local ion gyroradius and whose current density is an order of magnitude larger than for the usual tail current sheet. The negative space charge electric field associated with the thin current sheet and the related field‐aligned currents are consistent with the polarization Harang equatorward electric field.

Comment on 'An electrodynamical model for the ion behaviour in the final plasma focus stages'

For original paper see Zambreanu and Doloc, ibid., vol. 34, p. 1433 (1992). Zambreanu and Doloc presented an electrodynamic model for describing the electric and magnetic fields of a plasma focus discharge during the last stages of the current sheath (CS) evolution. Two different geometries were considered: a hollow cylindrical current distribution (of external radius rs and thickness Delta r) for the CS collapse phase, and a homogeneous column for the pinch phase. In both cases, a uniform current density j, in the layer and infinite column length was assumed. While explicit expressions for the axial component Az of the magnetic vector potential (in terms of rs, Delta r, the turning radius R0 of the CS, the cylindrical radial coordinate r and the discharge current I) were presented, the corresponding expressions for the scalar potential Phi were not given and thus the evaluation of the axial electric field Ez remained implicit. However, generic profiles of the fields were shown in the paper for both the hollow phase of the CS and the solid column phase. Kelly and Marquez analyse the column phase of the CS but the results can be extended to the hollow phase without difficulty.

Experimental and theoretical study of the CF4 DC glow discharge positive column

An experimental and theoretical study of the positive column of the CF4 DC glow discharge is presented. It includes the experimental determination of the reduced electric field Ez /N and the electron impact excitation rate constant KAr of the line ( lambda =750.3 nm, epsilon th=13.5 eV) of the actinometric addition (Ar) in CF4 plasma for a wide range of parameters (pressure p=0.2-2.3 Torr, current density j=4-35 mA cm-2). All experimental values of the reduced electric field can be described within the limits of experimental error by the universal dependence Ez/N on r0N (r0=0.9 cm, the discharge tube radius). Also the experimental dependence of kAr on Ez/N has been obtained. These results have been used to test different theoretical models of the CF4 discharge positive column. Comparison of the experimental and calculated values of Ez /N and KAr has shown the validity of the theoretical model developed in this work. This model takes into account the large negative ion concentration in the positive column and predicts its division into regions of ion-ion plasma (in the centre) and electro-ion plasma (near the tube wall). The model also accounts for the effect of non-locality of the electron energy distribution function. It has been shown that this effect can be accounted for by solving the Boltzmann equation for the EEDF in the spatially non-uniform case. The incorrectness of the notion of ambipolar diffusion in the plasma of a strongly electronegative gas with high negative ion concentrations has been reaffirmed.

On the image brightness of the trench bottom surface in a scanning electron microscope

Trajectories of secondary electrons (SEs) as an image signal in scanning electron microscopy are studied analytically in high-aspect-ratio submicron wide infinite trenches. It is found that the SE collection efficiency ξ, which is defined as the ratio of the number of SEs exiting the trench top surface divided by that emitted from the trench bottom surface, has the following dependencies on magnetic flux density Bz generated by an objective lens and electric field Ez. Here, Bz and Ez are the components perpendicular to the wafer surface. For a low Bz region corresponding to a usual operation condition, ξ decreases gradually but is almost constant at about 0.15 with increasing Bz for trenches 0.5 μm wide and 5 μm deep. For a high Bz region over 3 T, ξ increases with increasing Bz, since the cyclotron radius is fairly small compared with the trench width. A special superconducting magnet is necessary to reach the high Bz region. An external electric field Ez brings about the larger increase of ξ for the smaller SE energy εs. For εs=1 eV, Ez as large as 106 V/m is necessary to realize a 50% increase of ξ compared with the case of Ez=0 V/m, whereas for εs=0.1 eV, only about Ez=105 V/m is sufficient to realize the increase of 50%. On the other hand, experiments show that an electric field as large as 105 V/m is effective to achieve bright and clear observations of the bottom image.

Pulsed particle beams in the plasma focus and in astrophysics

Magnetic pinches in the laboratory 'plasma focus' and in astrophysical magnetic vortex tubes (MVTS) can become sources of relativistic charged particles. An axial current is confined to a thin annular channel defined by an electric double layer that is created during pinch by the azimuthal magnetic field Bphi . Constriction due to pinching and instability of drift velocity denude a region of current channel of free charges. The inductively maintained current J becomes a displacement current in the denuded region. Displacement current entails a growing axial electric field Ez and accumulating space charge. Ez attains maximum strength when all energy in Bphi is transferred into Ez and thereafter energy oscillates between the fields. In the MVT Bphi and hence J, reverse at mid-pinch, so that axial polarisation arises without a denuding mechanism. Thus Ez and J oscillate with reversal of polarity in the MVT, but not in the plasma focus. Reversal of Ez implies that pulsed beams of alternately negative and positive charges emerge from the MVT in both directions. From the plasma focus one obtains pulsed electron and positive-ion beams in opposite directions.

Lateral electromagnetic pulses generated by a vertical dipole on the boundary between two dielectrics

An exact solution in terms of elementary functions is obtained in the time domain for the vertical electric field Ez(ρ,t) and the transverse magnetic field Bφ(ρ,t) of a dipole located on the plane boundary z=0 between air (region 2, z<0) and a perfect dielectric (region 1, z>0) when the dipole is excited by a single delta-function current pulse. The vertical electric field on the boundary consists of a delta-function pulse that travels in the air with the velocity c, an oppositely directed delta-function pulse that travels in the dielectric with the smaller velocity c/ε1/2, an amplitude structure that varies in time between the two pulses, and a final static electric field due to the charges left on the dipole. The horizontal magnetic field is similar. For comparison, the vertical electric field in the equatorial plane of the same dipole in a homogeneous dielectric is also derived. The comparison indicates that the field along the boundary is a surface-wave or lateral pulse.

Magnetic Vortex Tubes in Astrophysics

The viscous forces on electrons and ions in a differentially rotating plasma drive an azimuthal current density jϕ, with axial magnetic field Bz which is shown to be proportional to plasma vorticity. Field strengths in agreement with those observed for both stars and galaxies are obtained, assuming that reactive forces prevent radial drifts of electrons or ions. Hierarchical vorticity is required in order to reconcile the small-scale length required for field changes with the large-scale length of observed fields. A vortex tube with magnetic field (magnetic vortex tube-MVT) becomes the basic entity for the origin of magnetic fields. Twisting of field lines by differential rotation causes (1ϕ,Bz,) →(jz, B𝓏',). When jzBϕ, > jϕ, Bz the MVT suffers magnetic pinch, and the axial current in the pinch flows through a cylindrical sheath with a radial electric field due to plasma polarization. An instability of drift velocity denudes a length R of the current channel of free charges, and the inductively maintained current then requires a displacement current in R and hence a growing axial electric field Ez, Ez is limited by transfer of the energy in Bz', to Ez, and thereafter the energy oscillates between the fields. On the stellar scale, evidence for polar MVT's comes from young stars with bipolar outflows of gas and jets. It is argued that end-on viewing of polar MVT's accounts for the kilogauss fields of Ap stars and the 1-100-MG fields of magnetic white dwarfs.