Magnetic Pressure Research Articles

A Semi-empirical Approach to the Dynamic Coupling of CMEs and Solar Wind

Coronal mass ejections (CMEs) are one of the most relevant phenomena for space weather. Moreover, CMEs can negatively affect essential services and facilities. Therefore, to protect society, we require well-grounded knowledge of the physics that governs the propagation of CMEs from near the Sun to the orbit of Earth. In this work, we deduce expressions to approximate the main forces that affect the dynamic coupling between CMEs and the surrounding solar wind. Therefore, we explore the CME–solar wind dynamic coupling from a magnetohydrodynamic perspective, which, combined with a few reasonable assumptions, allows us to obtain expressions for the thermal and magnetic pressure forces, viscous and dynamic drag, and gravity. We simultaneously use our expressions to compute the trajectories of 34 Earth-directed CMEs. Our results, which are compared with in situ data, show significant quantitative consistency; our synthetic transits closely mimic their in situ observed counterparts. We conclude from our results that magnetic, thermal, and dynamic drag significantly surpass the other forces such as dynamic agents of CMEs in the interplanetary medium. In addition, we find that the initial relative speed of CMEs and solar wind is a determinant factor for the dynamic behavior of CMEs. In other words, subsonic CMEs are initially mostly affected by magnetic and thermal pressure forces, whereas super-magnetosonic CMEs are initially governed by inertial drag.

On solute dispersion in an oscillatory magneto-hydrodynamics porous medium flow under the effect of heterogeneous and bulk chemical reaction

It is well known to all of us that there is a shortage of pure drinking water across the globe. Different types of pollutants (metallic and nonmetallic) mix with the water, and they cause several diseases such as cholera, typhoid, and various kinds of skin diseases, and even it is found that these kinds of particles may cause skin cancer. In the current study, an analytical solution of a two-dimensional convection–diffusion equation is obtained using Mei's multi-scale homogenization technique to investigate the influences of homogeneous and heterogeneous reactions on dispersion phenomena of the solute in an oscillatory magneto-hydrodynamics porous medium flow. In the appearance of the applied transverse magnetic field and oscillatory pressure gradient, a mathematical model of magneto-hydrodynamics dispersion between two parallel plates is presented. The analytical expressions of Taylor dispersivity, longitudinal mean and real concentration distributions, transverse concentration distribution, and transverse uniformity rate of the concentration are obtained. Also, the effect of various flow parameters such as Péclet number, Hartmann number, Schmidt number, Darcy number, oscillatory Reynolds number, porous parameter, dispersion time, downstream and upstream locations, chemical heterogeneous boundary reaction, and bulk reaction is discussed. How the transport phenomena of the solute display different natures with the various ranges of Darcy and Hartmann numbers with the aid of homogeneous and heterogeneous boundary reactions are highlighted. To show the effect of the absorption parameters on the transport coefficient, the third-order approximation of concentration is performed. It is seen that the dispersion coefficient (DT1) corresponding to the purely time-dependent flow increases with the enhancement of the Darcy number (Da). Moreover, it is found that as the Hartmann number (M) enhances, the total dispersivity (DT) decreases. Also, the transverse concentration distribution becomes flat for larger values of the Hartmann number. It is noticed that when Da≥1, the transverse variation curve turns into a trimodal distribution from a bimodal. This model may be helpful for separating various metallic and nonmetallic particles from the water to reduce the water pollution.

Ion and Electron Acceleration in Fully Kinetic Plasma Turbulence

Turbulence is often invoked to explain the origin of nonthermal particles in space and astrophysical plasmas. By means of 3D fully kinetic particle-in-cell simulations, we demonstrate that turbulence in low-β plasmas (β is the ratio of plasma pressure to magnetic pressure) accelerates ions and electrons into a nonthermal energy distribution with a power-law energy range. The ion spectrum is harder than the electron one, and both distributions get steeper for higher β. We show that the energization of electrons is accompanied by a significant energy-dependent pitch-angle anisotropy, with most electrons moving parallel to the local magnetic field, while ions stay roughly isotropic. We demonstrate that particle injection from the thermal pool occurs in regions of high current density. Parallel electric fields associated with magnetic reconnection are responsible for the initial energy gain of electrons, whereas perpendicular electric fields control the overall energization of ions. Our findings have important implications for the origin of nonthermal particles in space and astrophysical plasmas.

Electron temperature gradient driven transport model for tokamak plasmas

A new model for electron temperature gradient (ETG) modes is developed as a component of the multi-mode anomalous transport module [Rafiq et al., Phys Plasmas 20, 032506 (2013)] to predict a time-dependent electron temperature profile in conventional and low aspect ratio tokamaks. This model is based on two-fluid equations that govern the dynamics of low-frequency short- and long-wavelength electromagnetic toroidal ETG driven drift modes. A low collisionality NSTX discharge is used to scan the plasma parameter dependence on the ETG real frequency, growth rate, and electron thermal diffusivity. Electron thermal transport is discovered in the deep core region where modes are more electromagnetic in nature. Several previously reported gyrokinetic trends are reproduced, including the dependencies of density gradients, magnetic shear, β and gradient of β (β′), collisionality, safety factor, and toroidicity, where β is the ratio of the plasma pressure to the magnetic pressure. The electron heat diffusivity associated with the ETG mode is discovered to be on a scale consistent with the experimental diffusivity determined by power balance analysis.

Study of general relativistic magnetohydrodynamic accretion flow around black holes

ABSTRACT We present a novel approach to study the global structure of steady, axisymmetric, advective, magnetohydrodynamic (MHD) accretion flow around black holes in full general relativity (GR). Considering ideal MHD conditions and relativistic equation of state (REoS), we solve the governing equations to obtain all possible smooth global accretion solutions. We examine the dynamical and thermodynamical properties of accreting matter in terms of the flow parameters, namely energy (${\cal E}$), angular momentum (${\cal L}$), and local magnetic fields. For a vertically integrated GRMHD flow, we observe that toroidal component (bϕ) of the magnetic fields generally dominates over radial component (br) at the disc equatorial plane. This evidently suggests that toroidal magnetic field indeed plays important role in regulating the disc dynamics. We further notice that the disc remains mostly gas pressure (pgas) dominated (β = pgas/pmag > 1, pmag refers magnetic pressure) except at the near horizon region, where magnetic fields become indispensable (β ∼ 1). We observe that Maxwell stress is developed that eventually yields angular momentum transport inside the disc. Towards this, we calculate the viscosity parameter (α) that appears to be radially varying. In addition, we examine the underlying scaling relation between α and β, which clearly distinguishes two domains coexisted along the radial extent of the disc. Finally, we discuss the utility of the present formalism in the realm of GRMHD simulation studies.

Extended instability of kinetic ballooning modes induced by ion temperature gradient and impurity in tokamaks

Kinetic ballooning mode (KBM) instability in tokamak plasmas is studied with gyrokinetic theory. It extends and improves on the theory of higher order KBM which is not subject to second stabilization (Hirose et al 1994 Phys. Rev. Lett. 72 3993). It is verified that increasing ion temperature gradient (η i ) significantly enhances the instability of KBMs, and causes extended instability in the second MHD stable regime. Especially when η i ≳ 1, the mode is unstable almost in the whole β space from an experimental point of view, here β is the ratio of kinetic pressure to magnetic pressure. It is found that for the case with a relatively low safety factor (1 ≲ q ≲ 2) and η i ≈ 0, which is generally in the central regions of a tokamak plasma, the KBM instability can also be extended to the region of β or α far beyond the second MHD stability boundary due only to impurity effect, here α = −Rq 2(dβ/dr). It has characteristics similar to the extended instability induced by η i , while its instability window is narrower than the latter. From the observations, the unstable window of extended instability is finite. As the safety factor q and magnetic shear (≡ r dq/q dr) increases, the ‘theoretical’ critical β of the second stable regime decreases and the α threshold increases. When the impurity effect is combined with the η i effect, the unstable window of the extended instability induced by η i can be greatly reduced by the former. In some cases, for instance as η i ≳ 1 and q is larger, and in the presence of impurity with mediate mass number, the impurity effect can even make the second stable regime of ‘experimental significance’ re-appear in KBMs. The influence of η i and impurity effects on broadening mode structure of KBMs are smaller than q and . The stability boundary based on plane confirms the above results.

The dynamics of magnetized viscous-resistive ADAFs under a self-similar evolution

In this paper, we explore the self-similarity time evolution of a hot accretion flow around a compact object in the presence of a toroidal magnetic field. We focus on a simplified model which is axisymmetric, rotating, unsteady viscous-resistive under an advection-dominated stage. In this work, we suppose that both the kinematic viscosity and the magnetic diffusivity to be a result of turbulence in the accretion flow. To describe such a flow, we apply magneto-hydrodynamics equations in spherical coordinates, [Formula: see text] and adopt unsteady self-similar solutions. By neglecting the latitudinal dependence of the flow, we obtain a set of one-dimensional differential equations governing the accretion system. In this research, we encounter two parameters related to the magnetic field; one of them is, [Formula: see text], defined as the ratio of the magnetic pressure to the gas pressure and the other one, [Formula: see text] applied in the magnetic diffusivity definition. Our results show that [Formula: see text] is a function of position, and increases towards outer layers. On the other hand, we examine different strength of magnetic field by choosing different value of [Formula: see text] which is the value of [Formula: see text] at the inner edge of disc. We see that both [Formula: see text] and [Formula: see text] have positive effect on growing the radial infall velocity but density and gas pressure decrease by larger values of these parameters. Moreover, the rotational velocity and temperature of accreting material reduce considerably under the influence of a stronger magnetic field. We also focus on the behavior of the mass accretion rate appearing as a descending function of position. Finally, our solutions confirm that the radial trend of the physical quantities in a dynamical accretion flow is different from the ones in a steady flow. However, the effect of various parameters on the physical quantities in our model is qualitatively consistent with similar steady models.

Primordial magnetic fields in Population III star formation: a magnetized resolution study

ABSTRACT Population III (Pop III) stars form in groups due to the fragmentation of primordial gas. While uniform magnetic fields have been shown to support against fragmentation in present-day star formation, it is unclear whether realistic k3/2 primordial fields can have the same effect. We bypass the issues associated with simulating the turbulent dynamo by introducing a saturated magnetic field at equipartition with the velocity field when the central densities reach 10−13 g cm−3. We test a range of sink particle creation densities from 10−10 to 10−8 g cm−3. Within the range tested, the fields did not suppress fragmentation of the gas and hence could not prevent the degree of fragmentation from increasing with increased resolution. The number of sink particles formed and total mass in sink particles was unaffected by the magnetic field across all seed fields and resolutions. The magnetic pressure remained sub-dominant to the gas pressure except in the highest density regions of the simulation box, where it became equal to but never exceeded gas pressure. Our results suggest that the inclusion of magnetic fields in numerical simulations of Pop III star formation is largely unimportant.

An accelerated analytical method for predicting workpiece velocity and displacement during electromagnetic forming

This paper presents complementary analytical analyses, experiments, and numerical simulations of the electromagnetic tube compression (EMTC) process using a multi-turn axisymmetric coil with a field shaper. In earlier contributions, we proposed an analytical model capable of predicting the magnetic pressure, radial velocity, and radial displacement for EMTC. In the present paper, our understanding of EMTC is expanded with the aid of a modified analytical model, a series of experimental tests with various materials, and 3D coupled electromagnetic-mechanical numerical simulations. First, the analytical model was improved by generating elements across the entire landing area of the field shaper. This modification provided a more accurate induced magnetic pressure in the analytical model. In addition, the experimentally measured coupling coefficients between the coil, field shaper, and workpiece tube were directly incorporated into the analytical model as opposed to utilizing them as correction factors during the magnetic pressure calculation in the previous studies. In the proposed analytical model, at each time increment, the magnetic field geometry is updated in response to the tube deformation. Second, to assess the proposed analytical model, experimental tests with Photon Doppler Velocimetry (PDV) were carried out for three different materials with different thermo-mechanical properties, i.e., Al6061-T6, Cu101, and Cu260 (Brass). Third, to compare the computational cost of the analytical model and to determine the accuracy of the proposed analytical model compared to the existing software packages in the market, a 3D coupled electromagnetic-mechanical finite element model was used. To investigate the influence of discharge energy on tube deformation, all three methods were examined at three different charging energies, i.e., 2.4, 3.6, and 4.8 kJ. Reasonably good agreement between all three approaches validates the ability of the analytical model to accurately capture the deformation velocity and displacement for this complex multi-physics manufacturing process in a computationally cost-effective manner. Such an analytical model can be used as a base model for predicting the impact velocity during electromagnetic pulse welding and crimping processes prior to performing expensive and time-consuming experimental tests or numerical simulations.

CHANG-ES XXIX: the sub-kpc nuclear bubble of NGC 4438

ABSTRACT Active galactic nucleus (AGN) bubbles could play an important role in accelerating high-energy cosmic rays (CRs) and galactic feedback. Only in nearby galaxies could we have high enough angular resolution in multiwavelengths to study the sub-kpc environment of the AGN, where the bubbles are produced and strongly interact with the surrounding interstellar medium. In this paper, we present the latest Chandra observations of the Virgo cluster galaxy NGC 4438, which hosts multiscale bubbles detected in various bands. The galaxy also has low current star formation activity, so these bubbles are evidently produced by the AGN rather than a starburst. We present spatially resolved spectral analysis of the Chandra data of the ∼3 arcsec × 5 arcsec (${\sim} 200{\rm ~pc}\times 350\rm ~pc$) nuclear bubble of NGC 4438. The power-law tail in the X-ray spectra can be most naturally explained as synchrotron emission from high-energy CR leptons. The hot gas temperature increases, while the overall contribution of the non-thermal X-ray emission decreases with the vertical distance from the galactic plane. We calculate the synchrotron cooling time-scale of the CR leptons responsible for the non-thermal hard X-ray emission to be only a few tens to a few hundreds of years. The thermal pressure of the hot gas is about three times the magnetic pressure, but the current data cannot rule out the possibility that they are still in pressure balance. The spatially resolved spectroscopy presented in this paper may have important constraints on how the AGN accelerates CRs and drives outflows. We also discover a transient X-ray source only ∼5 arcsec from the nucleus of NGC 4438. The source was not detected in 2002 and 2008, but became quite X-ray bright in 2020 March, with an average 0.5–7 keV luminosity of ${\sim} 10^{39}\rm ~erg~s^{-1}$.

Magnetic Field Strength from Turbulence Theory. I. Using Differential Measure Approach

The mean plane-of-sky magnetic field strength is traditionally obtained from the combination of polarization and spectroscopic data using the Davis–Chandrasekhar–Fermi (DCF) technique. However, we identify the major problem of the DCF technique to be its disregard of the anisotropic character of MHD turbulence. On the basis of the modern MHD turbulence theory we introduce a new way of obtaining magnetic field strength from observations. Unlike the DCF technique, the new technique uses not the dispersion of the polarization angle and line-of-sight velocities, but increments of these quantities given by the structure functions. To address the variety of astrophysical conditions for which our technique can be applied, we consider turbulence in both media with magnetic pressure higher than the gas pressure, corresponding, e.g., to molecular clouds, and media with gas pressure higher than the magnetic pressure, corresponding to the warm neutral medium. We provide general expressions for arbitrary admixtures of Alfvén, slow, and fast modes in these media and consider in detail particular cases relevant to diffuse media and molecular clouds. We successfully test our results using synthetic observations obtained from MHD turbulence simulations. We demonstrate that our differential measure approach, unlike the DCF technique, can be used to measure the distribution of magnetic field strengths, can provide magnetic field measurements with limited data, and is much more stable in the presence of induced large-scale variations of nonturbulent nature. Furthermore, our study uncovers the deficiencies of earlier DCF research.

Remote Sensing of Coronal Forces during a Solar Prominence Eruption

We present a new methodology—the Keplerian Optical Dynamics Analysis (KODA)—for quantifying the dynamics of erupting magnetic structures in the solar corona. The technique involves adaptive spatiotemporal tracking of propagating intensity gradients and their characterization in terms of time-evolving Keplerian areas swept out by the position vectors of moving plasma blobs. Whereas gravity induces purely ballistic motions consistent with Kepler’s second law, noncentral forces such as the Lorentz force introduce nonzero torques resulting in more complex motions. KODA algorithms enable direct evaluation of the line-of-sight component of the net torque density from the image-plane projection of the areal acceleration. The method is applied to the prominence eruption of 2011 June 7, observed by the Solar Dynamics Observatory’s Atmospheric Imaging Assembly. Results obtained include quantitative estimates of the magnetic forces, field intensities, and blob masses and energies across a vast region impacted by the postreconnection redistribution of the prominence material. The magnetic pressure and energy are strongly dominant during the early, rising phase of the eruption, while the dynamic pressure and kinetic energy become significant contributors during the subsequent falling phases. Measured intensive properties of the prominence blobs are consistent with those of typical active-region prominences; measured extensive properties are compared with those of the whole pre-eruption prominence and the post-eruption coronal mass ejection of 2011 June 7, all derived by other investigators and techniques. We show that KODA provides valuable information on spatially and temporally dependent characteristics of coronal eruptions that is not readily available via alternative means, thereby shedding new light on the environment and evolution of these solar events.

Probing the nature of dissipation in compressible MHD turbulence

Context. An essential facet of turbulence is the space–time intermittency of the cascade of energy that leads to coherent structures of high dissipation. Aims. In this work, we aim to systematically investigate the physical nature of the intense dissipation regions in decaying isothermal magnetohydrodynamical (MHD) turbulence. Methods. We probed the turbulent dissipation with grid-based simulations of compressible isothermal decaying MHD turbulence. We took unprecedented care in resolving and controlling dissipation: we designed methods to locally recover the dissipation due to the numerical scheme. We locally investigated the geometry of the gradients of the fluid state variables. We developed a method to assess the physical nature of the largest gradients in simulations and to estimate their travelling velocity. Finally, we investigated their statistics. Results. We find that intense dissipation regions mainly correspond to sheets; locally, density, velocity, and magnetic fields vary primarily in one direction. We identify these highly dissipative regions as fast and slow shocks or Alfvén discontinuities (Parker sheets or rotational discontinuities). On these structures, we find the main deviation from a 1D planar steady-state is mass loss in the plane of the structure. We investigated the effect of initial conditions, which yield different imprints at an early time on the relative distributions among these four categories. However, these differences fade out after about one turnover time, at which point they become dominated by weakly compressible Alfvén discontinuities. We show that the magnetic Prandtl number has little influence on the statistics of these discontinuities, but it controls the ohmic versus viscous heating rates within them. Finally, we find that the entrance characteristics of the structures (such as entrance velocity and magnetic pressure) are strongly correlated. Conclusions. These new methods allow us to consider developed compressible turbulence as a statistical collection of intense dissipation structures. This can be used to post-process 3D turbulence with detailed 1D models apt for comparison with observations. It could also be useful as a framework to formulate new dynamical properties of turbulence.

Baroentropy change estimation using modified Maxwell equation through magnetization and resistivity measurements under pressure: An indirect method of barocaloric effect

We investigate the baroentropy change on manganites (Δ S b M and Δ S b M- ρ ) using modified form of Maxwell’s equation through magnetization and magnetization-resistivity measurements. Hence, we choose two Mn-site doped pervoskite manganites Pr 0.6 Ca 0.4 Mn 0.96 Co 0.04 O 3 and Pr 0.6 Ca 0.4 Mn 0.96 Cr 0.04 O 3 due to strong correlation between magnetic and electrical properties. The two external perturbations such as magnetic field and hydrostatic pressure have a similar influence on magnetic and transport properties of manganite systems due to its strong coupling between spin, charge, and orbital degrees of freedom. Baroentropy change, similar to magneto entropy change, could be estimated by replacing magnetic field in Maxwell’s equation by pressure in perovskite manganites. The estimated values of Δ S b M and Δ S b M-ρ using proposed equations well agree with each other, justifying the use of these equations. As these values are deduced from pressure dependent magnetization and resistivity measurements, this method of baroentropy change estimation is very useful as well as reliable in order to select application-oriented systems from the manganites family. • H and P have a similar influence on magnetic and transport properties of manganites. • Two modified forms of Maxwell’s equation are proposed to estimate baroentropy changes. • ΔS b M and ΔS b M-ρ values completely rely on magnetization and resistivity of a system. • P and H increase the baroentropy change of selected Co and Cr doped systems. • These are reliable for manganites in which analogue in magnetic and transport properties.

Macro-mechanical properties of magnetorheological fluids based on body-centered cubic structure

This paper addresses the problem that the microstructure model of magnetorheological fluid established by traditional single-chain or multi-chain dense rows is unable to accurately describe the rheological behavior and the sudden change of macroscopic mechanical properties under the action of an applied magnetic field, and analyzes the stable cluster-like structure formed by a specific volume fraction of magnetorheological fluids in a micro-narrow channel under the action of external magnetic field and extrusion pressure. This paper also establishes the equations of motion and dynamics of magnetic particles under the action of external magnetic field, analyzes the dynamic evolution of particle microstructure, performs numerical simulations of two-dimensional chaining using Matlab, and establishes a microscopic observation test bench for comparison and verification; and it establishes a model of complex cluster-like structure of magnetorheological fluids body-centered cubic, and analyzes the system energy, stability and force of the body-centered cubic structure based on the minimum system energy theory and Hertzian contact theory; and further establishes a shear yield stress model based on the body-centered cubic microstructure to analyze the macroscopic mechanical properties of magnetorheological fluids, thereby enriching the theoretical system of extrusion strengthening of magnetorheological fluids in the microscale.

Influence of magnetic configuration properties on kinetic ballooning modes in W7-X

The stability properties of kinetic ballooning modes are investigated for a number of magnetic configurations of the stellarator Wendelstein 7-X. In particular, we consider the effects of the vacuum rotational transform,${\raise.1pt-\kern-6pt\iota}$, and the mirror ratio. The analysis sheds light on the interplay between global magnetohydrodynamic configuration properties and local gyrokinetic stability, and is instrumental in the design of high-$\beta$(the ratio of kinetic to magnetic pressure) operation scenarios. In particular, it is demonstrated that some Wendelstein 7-X magnetic configurations have a relatively low kinetic ballooning mode threshold.

Effects of the Planetary Field on the Accretion Process of a Planet in the Final Stage of Giant Planet Formation

Recent studies suggest that the magnetic field may play an important role in the formation of giant planets during the final stage of the formation process. In this paper, we construct a circumplanetary system around a planet that is in the final formation stage to investigate the effects of the planetary magnetic field on the accretion process of the planet at this stage. We find that at the early times of our magneto-hydrodynamic (MHD) simulation, the magnetic loops connecting the planet and the circumplanetary material inflate upward due to the build-up of the toroidal field pressure with magnetic islands forming inside the loops, which changes the flow pattern above the planet in comparison with the hydrodynamic case. We find that a low-density gap, which is produced by the strong magnetic pressure, appears along the disk’s surface and expands as the system evolves. Accompanied by the accretion flow above the disk surface, the disk surface field lines can reconnect with the magnetic loops anchored on the planet. Thus, the material above the disk’s surface can permeate into the loops anchored on the planet via reconnection and can be accreted to the planet through the loops. Comparing the results in the hydrodynamic and MHD simulations, we find that the mass accretion rate and the angular momentum transport rate from the infalling gas to the planet do not change apparently when the effects of the magnetic field are included, but these rates from the circumplanetary disk to the planet increase significantly by an order of magnitude.

On Regularity Criteria via Pressure for the 3D MHD Equations in a Half Space

In this paper, we give regularity criteria in terms of the magnetic pressure in Lorentz spaces.

Similarity solutions for a magnetized supercritical accretion disc around a rotating object

ABSTRACT The effect of toroidal magnetic fields on a supercritical accretion disc (slim disc) around a rotating object is examined. In this research, it is supposed that angular momentum transport is due to viscous turbulence and the α-prescription is used for the kinematic coefficient of viscosity. Moreover, the general relativistic effects are neglected. The degree of advection that demonstrates the fraction of energy that accretes by matter on to the central object is considered by f parameter. For the steady-state structure of such accretion flows, a set of self-similar solution is presented. Our solutions will include two important non-dimensional parameters β and a. β is the ratio of the magnetic pressure to the gas pressure, the so-called friction of magnetic pressure, which shows the magnetic field strength. The ratio of the angular velocities of the central body and the accretion flow is indicated by the rotating parameter a. The possible combined effects of magnetic field, spin of central object, and degree of advection are investigated. We also show the effect of rotating parameter a on the physical quantities of disc is different for co-rotating and counter-rotating flows. Moreover, by increasing the degree of advection and strength of magnetic field, the behaviour of the radial and angular velocities becomes reversed with respect to a. The model implies that the surface temperature, thickness, and luminosity of disc strongly depend on rotation parameter and strength of magnetic field.

Coupling between multiple coaxial antennas surrounding a plasma column produced by helicon antenna

AbstractThe coupling physics between multiple coaxial antennas separated axially along plasma column produced by helicon antenna are investigated. Experiments are carried out on a recently built device, named Physics ANd Thruster oriented HElicon Research (PANTHER) with the upgrade of second‐stage antennas. Mutual induction currents on these antennas are measured for two cases: without plasma discharge and with plasma discharge, respectively. It is found that the existence of a plasma column going through these antennas increases the coupling effects among them significantly. Theoretical analyses from the perspectives of transformer and magnetic permeability and moment confirm the reasonability of this phenomenon. Equivalent circuit models and governing equations are provided for preliminary analyses, covering both single‐antenna‐driven cases and dual‐antenna‐driven cases. The effects of confining magnetic field and background pressure on the mutual coupling are shown as well. This work is of particular interest for electrodeless plasma source or thruster which employs multiple coaxial antennas for ionization and acceleration. The analogy of a plasma column going through multiple antennas to a magnetic core for a transformer is an innovative attempt.