Journal articles: 'Plasma flow in magnetic field'

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Ho, Ching Yen, Yu Hsiang Tsai, and Chung Ma. "Effects of External Magnetic Field on Intensity of Plasma Flow." Applied Mechanics and Materials 597 (July 2014): 272–75. http://dx.doi.org/10.4028/www.scientific.net/amm.597.272.

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This paper investigates the intensity distribution along the radial direction for plasma flow subject to external magnetic Field. The toroidal external magnetism is applied in the transverse direction of plasma flow. Considering the steady-state continuity and momentum of the plasma flow subject to external magnetic field, the intensity profile of the plasma is obtained. The results quantitatively verify the intensity enhancement of the plasma with the increasing external magnetic field.

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Nickeler, D. H., and T. Wiegelmann. "Thin current sheets caused by plasma flow gradients in space and astrophysical plasma." Annales Geophysicae 28, no. 8 (August 13, 2010): 1523–32. http://dx.doi.org/10.5194/angeo-28-1523-2010.

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Abstract. Strong gradients in plasma flows play a major role in space and astrophysical plasmas. A typical situation is that a static plasma equilibrium is surrounded by a plasma flow, which can lead to strong plasma flow gradients at the separatrices between field lines with different magnetic topologies, e.g., planetary magnetospheres, helmet streamers in the solar corona, or at the boundary between the heliosphere and interstellar medium. Within this work we make a first step to understand the influence of these flows towards the occurrence of current sheets in a stationary state situation. We concentrate here on incompressible plasma flows and 2-D equilibria, which allow us to find analytic solutions of the stationary magnetohydrodynamics equations (SMHD). First we solve the magnetohydrostatic (MHS) equations with the help of a Grad-Shafranov equation and then we transform these static equilibria into a stationary state with plasma flow. We are in particular interested to study SMHD-equilibria with strong plasma flow gradients perpendicular to separatrices. We find that induced thin current sheets occur naturally in such situations. The strength of the induced currents depend on the Alfvén Mach number and its gradient, and on the magnetic field.

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MOHAPATRA, RANJITA K., P. S. SAUMIA, and AJIT M. SRIVASTAVA. "ENHANCEMENT OF FLOW ANISOTROPIES DUE TO MAGNETIC FIELD IN RELATIVISTIC HEAVY-ION COLLISIONS." Modern Physics Letters A 26, no. 33 (October 30, 2011): 2477–86. http://dx.doi.org/10.1142/s0217732311036711.

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It is known that the presence of background magnetic field in cosmic plasma distorts the acoustic peaks in CMBR. This primarily results from different types of waves in the plasma with velocities depending on the angle between the magnetic field and the wave vector. We consider the consequences of these effects in relativistic heavy-ion collisions where very strong magnetic fields arise during early stages of the plasma evolution. We show that flow coefficients can be significantly affected by these effects when the magnetic field remains strong during early stages due to strong induced fields in the conducting plasma. In particular, the presence of magnetic field can lead to enhancement in the elliptic flow coefficient v2.

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Alexeev, I. I., and V. V. Kalegaev. "Magnetic field and plasma flow structure near the magnetopause." Journal of Geophysical Research 100, A10 (1995): 19267. http://dx.doi.org/10.1029/95ja01345.

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Korobkin, Yu V., N. V. Lebedev, and V. L. Paperny. "Charge separation of plasma flow in curvilinear magnetic field." Technical Physics Letters 38, no. 3 (March 2012): 254–57. http://dx.doi.org/10.1134/s1063785012030248.

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Kotalik, P., and H. Nishiyama. "An effect of magnetic field on arc plasma flow." IEEE Transactions on Plasma Science 30, no. 1 (February 2002): 160–61. http://dx.doi.org/10.1109/tps.2002.1003973.

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Juusola, Liisa, Sanni Hoilijoki, Yann Pfau-Kempf, Urs Ganse, Riku Jarvinen, Markus Battarbee, Emilia Kilpua, Lucile Turc, and Minna Palmroth. "Fast plasma sheet flows and X line motion in the Earth's magnetotail: results from a global hybrid-Vlasov simulation." Annales Geophysicae 36, no. 5 (September 10, 2018): 1183–99. http://dx.doi.org/10.5194/angeo-36-1183-2018.

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Abstract. Fast plasma flows produced as outflow jets from reconnection sites or X lines are a key feature of the dynamics in the Earth's magnetosphere. We have used a polar plane simulation of the hybrid-Vlasov model Vlasiator, driven by steady southward interplanetary magnetic field and fast solar wind, to study fast plasma sheet ion flows and related magnetic field structures in the Earth's magnetotail. In the simulation, lobe reconnection starts to produce fast flows after the increasing pressure in the lobes has caused the plasma sheet to thin sufficiently. The characteristics of the earthward and tailward fast flows and embedded magnetic field structures produced by multi-point tail reconnection are in general agreement with spacecraft measurements reported in the literature. The structuring of the flows is caused by internal processes: interactions between major X points determine the earthward or tailward direction of the flow, while interactions between minor X points, associated with leading edges of magnetic islands carried by the flow, induce local minima and maxima in the flow speed. Earthward moving flows are stopped and diverted duskward in an oscillatory (bouncing) manner at the transition region between tail-like and dipolar magnetic fields. Increasing and decreasing dynamic pressure of the flows causes the transition region to shift earthward and tailward, respectively. The leading edge of the train of earthward flow bursts is associated with an earthward propagating dipolarization front, while the leading edge of the train of tailward flow bursts is associated with a tailward propagating plasmoid. The impact of the dipolarization front with the dipole field causes magnetic field variations in the Pi2 range. Major X points can move either earthward or tailward, although tailward motion is more common. They are generally not advected by the ambient flow. Instead, their velocity is better described by local parameters, such that an X point moves in the direction of increasing reconnection electric field strength. Our results indicate that ion kinetics might be sufficient to describe the behavior of plasma sheet bulk ion flows produced by tail reconnection in global near-Earth simulations. Keywords. Magnetospheric physics (magnetospheric configuration and dynamics; plasma sheet) – space plasma physics (numerical simulation studies)

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Rincon, François, Francesco Califano, Alexander A. Schekochihin, and Francesco Valentini. "Turbulent dynamo in a collisionless plasma." Proceedings of the National Academy of Sciences 113, no. 15 (March 29, 2016): 3950–53. http://dx.doi.org/10.1073/pnas.1525194113.

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Magnetic fields pervade the entire universe and affect the formation and evolution of astrophysical systems from cosmological to planetary scales. The generation and dynamical amplification of extragalactic magnetic fields through cosmic times (up to microgauss levels reported in nearby galaxy clusters, near equipartition with kinetic energy of plasma motions, and on scales of at least tens of kiloparsecs) are major puzzles largely unconstrained by observations. A dynamo effect converting kinetic flow energy into magnetic energy is often invoked in that context; however, extragalactic plasmas are weakly collisional (as opposed to magnetohydrodynamic fluids), and whether magnetic field growth and sustainment through an efficient turbulent dynamo instability are possible in such plasmas is not established. Fully kinetic numerical simulations of the Vlasov equation in a 6D-phase space necessary to answer this question have, until recently, remained beyond computational capabilities. Here, we show by means of such simulations that magnetic field amplification by dynamo instability does occur in a stochastically driven, nonrelativistic subsonic flow of initially unmagnetized collisionless plasma. We also find that the dynamo self-accelerates and becomes entangled with kinetic instabilities as magnetization increases. The results suggest that such a plasma dynamo may be realizable in laboratory experiments, support the idea that intracluster medium turbulence may have significantly contributed to the amplification of cluster magnetic fields up to near-equipartition levels on a timescale shorter than the Hubble time, and emphasize the crucial role of multiscale kinetic physics in high-energy astrophysical plasmas.

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Petralia, A., F. Reale, and P. Testa. "Guided flows in coronal magnetic flux tubes." Astronomy & Astrophysics 609 (December 22, 2017): A18. http://dx.doi.org/10.1051/0004-6361/201731827.

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Context. There is evidence that coronal plasma flows break down into fragments and become laminar. Aims. We investigate this effect by modelling flows confined along magnetic channels. Methods. We consider a full magnetohydrodynamic (MHD) model of a solar atmosphere box with a dipole magnetic field. We compare the propagation of a cylindrical flow perfectly aligned with the field to that of another flow with a slight misalignment. We assume a flow speed of 200 km s-1 and an ambient magnetic field of 30 G. Results. We find that although the aligned flow maintains its cylindrical symmetry while it travels along the magnetic tube, the misaligned one is rapidly squashed on one side, becoming laminar and eventually fragmented because of the interaction and back-reaction of the magnetic field. This model could explain an observation made by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory of erupted fragments that fall back onto the solar surface as thin and elongated strands and end up in a hedge-like configuration. Conclusions. The initial alignment of plasma flow plays an important role in determining the possible laminar structure and fragmentation of flows while they travel along magnetic channels.

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Alekseeva, Liliya M. "Instabilities of a Hall plasma flowing across a magnetic field." Laser and Particle Beams 15, no. 1 (March 1997): 65–72. http://dx.doi.org/10.1017/s0263034600010752.

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Under certain restrictions imposed on the plasma parameters, an analytical 2D solution to the magnetohydrodynamic equations, taking into account the Hall effect [of the HMHD (Hall magnetohydrodynamic) equations], is found for the case when plasma flows across a magnetic field. This solution has the form of the sum of a rather arbitrary steady flow and a small time-dependent disturbance. We show that waves of a purely acoustic nature can propagate against the background of the flow. The magnetic field manifests itself in this process only in that it produces an effective gravity force, the “gravitational” acceleration being proportional ωeτe. Like acoustic-gravity waves in the atmosphere, such quasiacoustic-gravity (QAG) waves in a plasma increase greatly in their amplitude as they propagate “upward,” that is, in this case, to the anode of an accelerating plasma channel. The existence of a rather general dimensionless similarity criterion is also shown. It can be found directly from the structure of the HMHD equations without any restrictions as to the plasma parameters.

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Wei, Jian Ping, and Da Pei Tang. "Flow Characteristics of DC Plasma Torch Controlled by Magnetic Field." Applied Mechanics and Materials 268-270 (December 2012): 610–13. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.610.

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A magneto-hydrodynamic(MHD) model of magnetic controlled DC plasma torch is presented. The model includes the Navier-Stokes and the energy equations modified by the addition of some source terms, which reflect the Lorentz force due to the self-induced and the external magnetic fields, the radiative cooling and the Joule heating. In addition, the generalized Ohm's law, and the Maxwell's equations are also modeled. The MHD model is solved with the software FLUENT . The distribution of the velocity in the torch is obtained. The results show that the larger the current size of external current-carrying solenoid coil is , the greater the radial velocity and swirl velocity in the torch outlet are.

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Tang, Da Pei, Qing Gao, Ying Hui Li, and Fan Xiu Lu. "Effect of External Magnetic Field on the Flow and Heat Transfer in DC Arc Plasma Torch." Advanced Materials Research 97-101 (March 2010): 2797–800. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.2797.

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A multiple fields’ coupled model of new magnetic controlled DC plasma torch, which was used for CVD diamond film, was presented. In this model, the effects of electric field and magnetic field on the flow field and temperature field were taken into account, and the fluid dynamics equations were modified by the addition of some source terms relating to electromagnetic field, such as Lorentz force, joule heating, and radiative cooling. Conversely, the generalized ohm’s law was used to solve the current density, which reflected the effects of flow field and temperature field on the electric field and magnetic field. In addition, the rest Maxwell’s equations and external solenoid magnetic field equation were also modeled. In order to know the effect of external magnetic field on the torch, the current intensity of external solenoid was chosen to simulate its influence on the flow and heat transfer in the torch. Results show that external magnetic field plays a part in stirring the plasma, which is advantageous for the preparation of diamond film. The larger the external solenoid current intensity is, the better the uniformity of the temperature and velocity of plasma is.

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Bobashev, Sergei V., Yurii P. Golovachov, and David M. Van Wie. "Deceleration of Supersonic Plasma Flow by an Applied Magnetic Field." Journal of Propulsion and Power 19, no. 4 (July 2003): 538–46. http://dx.doi.org/10.2514/2.6164.

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Gupta, Sneha, and Devendra Sharma. "Plasma flow equilibria in 2D cylindrically symmetric expanding magnetic field." Physics of Plasmas 26, no. 9 (September 2019): 093501. http://dx.doi.org/10.1063/1.5090559.

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Timofeev, A. V. "Stability of the collisional plasma flow in a magnetic field." JETP Letters 97, no. 1 (March 2013): 5–9. http://dx.doi.org/10.1134/s0021364013010116.

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16

Hill, Jacqueline L., Amir Seyhoonzadeh, Hong-Young Chang, and Karl E. Lonngren. "On the flow of plasma around a dipole magnetic field." Radio Science 22, no. 7 (December 1987): 1211–18. http://dx.doi.org/10.1029/rs022i007p01211.

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17

Nakamura, R., D. N. Baker, D. H. Fairfield, D. G. Mitchell, and R. L. McPherron. "Plasma flow and magnetic field characteristics in the midtail region." Advances in Space Research 13, no. 4 (April 1993): 223–28. http://dx.doi.org/10.1016/0273-1177(93)90337-b.

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18

Frolova, Valeria P., Alexey G. Nikolaev, Efim M. Oks, Alexander V. Sidorov, Alexey V. Vizir, Alexander V. Vodopyanov, Anatoly Yu Yushkov, and Georgy Yu Yushkov. "Supersonic Flow of Vacuum Arc Plasma in a Magnetic Field." IEEE Transactions on Plasma Science 49, no. 9 (September 2021): 2478–89. http://dx.doi.org/10.1109/tps.2021.3088154.

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Dubinin, E. M., K. Sauer, and J. F. McKenzie. "Nonlinear 1-D stationary flows in multi-ion plasmas – sonic and critical loci – solitary and "oscillatory" waves." Annales Geophysicae 24, no. 11 (November 22, 2006): 3041–57. http://dx.doi.org/10.5194/angeo-24-3041-2006.

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Abstract. One-dimensional stationary flows of a plasma consisting of two ion populations and electrons streaming against a heavy ion cloud are studied. The flow structure is critically governed by the position of sonic and critical points, at which the flow is shocked or choked. The concept of sonic and critical points is suitably generalized to the case of multi-ion plasmas to include a differential ion streaming. For magnetic field free flows, the sonic and critical loci in the (upx, uhx) space coincide. Amongst the different flow patterns for the protons and heavy ions, there is a possible configuration composed of a "heavy ion shock" accompanied by a proton rarefaction. The magnetic field introduces a "stiffness" for the differential ion streaming transverse to the magnetic field. In general, both ion fluids respond similarly in the presence of "ion obstacle"; the superfast (subfast) flows are decelerated (accelerated). The collective flow is choked when the dynamic trajectory (upx, uhx) crosses the critical loci. In specific regimes the flow contains a sequence of solitary structures and as a result, the flow is strongly bunched. In each such substructure the protons are almost completely replaced by the heavies. A differential ion streaming is more accessible in the collective flows oblique to the magnetic field. Such a flexibility of the ion motion is determined by the properties of energy integrals and the Bernoulli energy functions of each ion species. The structure of flows, oblique to the magnetic field, depends critically on the velocity regime and demonstrates a rich variety of solitary and oscillatory nonlinear wave structures. The results of the paper are relevant to the plasma and field environments at comets and planets through the interaction with the solar wind.

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Gus'kov, S. Yu, V. B. Rozanov, and T. Pisarczyk. "Magnetic control of the plasma flows in laser targets." Laser and Particle Beams 12, no. 3 (September 1994): 371–77. http://dx.doi.org/10.1017/s0263034600008223.

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The idea of controlling the plasma flows in laser targets by action of a strong external magnetic field (H ≥ 1 MG) is presented. The magnetic control of plasma flows for the keeping of a transparency of entrance holes of indirect-compression targets and other type targets operating at an introduction of the laser beams into the interior of the target is suggested. It is shown that the magnetic field, transverse versus the direction of the propagation of the plasma flow with an intensity of 2–4 MG, causes a decrease (1.5–3 times) of the closing speed of holes for the laser beam introduction into the hohlraum target.

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Mitrofanov, K. N., V. I. Krauz, V. V. Myalton, E. P. Velikhov, V. P. Vinogradov, and Yu V. Vinogradova. "Magnetic field distribution in the plasma flow generated by a plasma focus discharge." Journal of Experimental and Theoretical Physics 119, no. 5 (November 2014): 910–23. http://dx.doi.org/10.1134/s1063776114110168.

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IQBAL, M., and P. K. SHUKLA. "Beltrami fields in a hot electron–positron–ion plasma." Journal of Plasma Physics 78, no. 3 (February 6, 2012): 207–10. http://dx.doi.org/10.1017/s0022377812000050.

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AbstractA possibility of relaxation of relativistically hot electron and positron (e − p) plasma with a small fraction of hot or cold ions has been investigated analytically. It is observed that a strong interaction of plasma flow and field leads to a non-force-free relaxed magnetic field configuration governed by the triple curl Beltrami (TCB) equation. The triple curl Beltrami (TCB) field composed of three different Beltrami fields gives rise to three multiscale relaxed structures. The results may have the strong relevance to some astrophysical and laboratory plasmas.

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Yahnin, A. G., I. V. Despirak, A. A. Lubchich, B. V. Kozelov, N. P. Dmitrieva, M. A. Shukhtina, and H. K. Biernat. "Indirect mapping of the source of the oppositely directed fast plasma flows in the plasma sheet onto the auroral display." Annales Geophysicae 24, no. 2 (March 23, 2006): 679–87. http://dx.doi.org/10.5194/angeo-24-679-2006.

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Abstract. Data from Polar and Geotail spacecraft are combined to investigate the relationship between locations of active auroras and the magnetotail plasma sheet region where reversed fast plasma flows are generated during substorms. Using the magnetospheric magnetic field model, it is shown that at the beginning of the tailward fast flow the ionospheric footprint of the spacecraft measuring the flow tends to be located poleward of the auroral bulge. The spacecraft within the earthward flow is mapped equatorward of the poleward edge of the auroral bulge. We conclude that a source of the fast plasma flows is conjugated with the poleward edge of the auroral bulge. Analysis of the behavior of the plasma and the magnetic field in the vicinity of the source of the diverging flows allows us to conclude that the source region, interpreted as the magnetic reconnection site, coincides with the region of the cross-tail current reduction, and the tailward propagation of the region is associated with the tailward propagation of the current disruption front.

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Campos Rozo, J. I., D. Utz, S. Vargas Domínguez, A. Veronig, and T. Van Doorsselaere. "Photospheric plasma and magnetic field dynamics during the formation of solar AR 11190." Astronomy & Astrophysics 622 (February 2019): A168. http://dx.doi.org/10.1051/0004-6361/201832760.

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Context. The Sun features on its surface typical flow patterns called the granulation, mesogranulation, and supergranulation. These patterns arise due to convective flows transporting energy from the interior of the Sun to its surface. The other well known elements structuring the solar photosphere are magnetic fields arranged from single, isolated, small-scale flux tubes to large and extended regions visible as sunspots and active regions. Aims. In this paper we will shed light on the interaction between the convective flows in large-scale cells as well as the large-scale magnetic fields in active regions, and investigate in detail the statistical distribution of flow velocities during the evolution and formation of National Oceanic and Atmospheric Administration active region 11190. Methods. To do so, we employed local correlation tracking methods on data obtained by the Solar Dynamics Observatory in the continuum as well as on processed line-of-sight magnetograms. Results. We find that the flow fields in an active region can be modelled by a two-component distribution. One component is very stable, follows a Rayleigh distribution, and can be assigned to the background flows, whilst the other component is variable in strength and velocity range and can be attributed to the flux emergence visible both in the continuum maps as well as magnetograms. Generally, the plasma flows, as seen by the distribution of the magnitude of the velocity, follow a Rayleigh distribution even through the time of formation of active regions. However, at certain moments of large-scale fast flux emergence, a second component featuring higher velocities is formed in the velocity magnitudes distribution. Conclusions. The plasma flows are generally highly correlated to the motion of magnetic elements and vice versa except during the times of fast magnetic flux emergence as observed by rising magnetic elements. At these times, the magnetic fields are found to move faster than the corresponding plasma.

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Neubauer, F. M. "The Magnetic Field Structure of the Cometary Plasma Environment." International Astronomical Union Colloquium 116, no. 2 (1991): 1107–24. http://dx.doi.org/10.1017/s0252921100012847.

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AbstractThe plasma surrounding a comet has the interplanetary magnetic field frozen in. The geometric interpretation of this property is considered. The frozen-in character of the magnetic field leads to the draping of magnetic field lines around the inner coma, where, by exclusion of the inner purely cometary ionosphere, a magnetic cavity is formed inside a region of magnetic field pile-up. The consequences of these physical processes can nicely be diagnosed and tested by interplanetary tangential discontinuities serving as tracers of the magnetoplasma flow. The topology of the magnetic field around the cavity and the shape of the ionopause, as well as the formation of the magnetic tail, are discussed. Particularly in the outer regions, the magnetic field is disturbed by strong magnetic turbulence. This turbulence plays a role in accelerating cometary and also solar wind ions to high energies.

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Nishikawa, K. I., P. Hardee, B. Zhang, I. Duţan, M. Medvedev, E. J. Choi, K. W. Min, et al. "Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability." Annales Geophysicae 31, no. 9 (September 6, 2013): 1535–41. http://dx.doi.org/10.5194/angeo-31-1535-2013.

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Abstract. We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic jet and an unmagnetized sheath plasma. We have examined the strong magnetic fields generated by kinetic shear (Kelvin–Helmholtz) instabilities. Compared to the previous studies using counter-streaming performed by Alves et al. (2012), the structure of the kinetic Kelvin–Helmholtz instability (KKHI) of our jet-sheath configuration is slightly different, even for the global evolution of the strong transverse magnetic field. In our simulations the major components of growing modes are the electric field Ez, perpendicular to the flow boundary, and the magnetic field By, transverse to the flow direction. After the By component is excited, an induced electric field Ex, parallel to the flow direction, becomes significant. However, other field components remain small. We find that the structure and growth rate of KKHI with mass ratios mi/me = 1836 and mi/me = 20 are similar. In our simulations saturation in the nonlinear stage is not as clear as in counter-streaming cases. The growth rate for a mildly-relativistic jet case (γj = 1.5) is larger than for a relativistic jet case (γj = 15).

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BOROVSKY, JOSEPH E., RICHARD C. ELPHIC, HERBERT O. FUNSTEN, and MICHELLE F. THOMSEN. "The Earth's plasma sheet as a laboratory for flow turbulence in high-β MHD." Journal of Plasma Physics 57, no. 1 (January 1997): 1–34. http://dx.doi.org/10.1017/s0022377896005259.

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The bulk flows and magnetic-field fluctuations of the plasma sheet are investigated using single-point measurements from the ISEE-2 Fast Plasma Experiment and fluxgate magnetometer. Ten several-hour-long intervals of continuous data (with 3 s and 12 s time resolution) are analysed. The plasma-sheet flow appears to be strongly ‘turbulent’ (i.e. the flow is dominated by fluctuations that are unpredictable, with rms velocities[Gt ]mean velocities and with field fluctuations≈mean fields). The flow velocities are typically sub-Alfvénic. The flow-velocity probability distribution P(v) is constructed, and is found to be well fitted by exponential functions. Autocorrelation functions [Ascr ](τ) are constructed, and the autocorrelation times τcorr for the flow velocities are found to be about 2 min. From the flow measurements, an estimate of the mixing length in the plasma sheet is produced, yielding Lmix≈2 Earth radii; correspondingly, the plasma-sheet material appears to be well mixed in density and temperature. An eddy viscosity for the plasma sheet is also estimated. Power spectra, which are constructed from the v(t) and B(t) time series, have portions that are power laws with spectral indices that are near the range of those expected for turbulence theories. The plasma sheet may provide a laboratory for the study of turbulence in parameter regimes different from that of solar-wind turbulence: the plasma sheet is a β[Gt ]1, hot-ion plasma, and the turbulence may be strongly driven rather than well developed. The turbulent nature of the flow and the disordered nature of the magnetic field have implications for the transport of plasma-sheet material, for the penetration of the solar-wind electric field into the plasma sheet, and for the calculation of particle orbits in the magnetotail.

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Johansson, T., J. W. Bonnell, C. Cully, E. Donovan, J. Raeder, S. Eriksson, L. Andersson, et al. "Observation of an inner magnetosphere electric field associated with a BBF-like flow and PBIs." Annales Geophysicae 27, no. 4 (April 2, 2009): 1489–500. http://dx.doi.org/10.5194/angeo-27-1489-2009.

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Abstract. Themis E observed a perpendicular (to the magnetic field) electric field associated with an Earthward plasma flow at XGSM=−9.6 RE on 11 January 2008. The electric field observation resembles Cluster observations closer to Earth in the auroral region. The fast plasma flow shared some characteristics with bursty bulk flows (BBFs) but did not meet the usual criteria in maximum velocity and duration to qualify as one. Themis C observed the same flow further downtail but Themis D, separated by only 1 RE in azimuthal direction from Themis E, did not. At the time of the electric field and ion flow event, the all-sky imager and ground-based magnetometer at Rankin Inlet observed Poleward Boundary Intensifications (PBIs) and a negative bay signature. None of the other Themis ground-based observatories recorded any significant auroral or magnetic field activity, indicating that this was a localized activity. The joint Themis in situ and ground-based observations suggest that the two observations are related. This indicates that auroral electric fields can extend to regions much farther out than previously seen in Cluster observations.

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Klimov, Aleksandr, and Aleksey Zenin. "Surface treatment by the ion flow from electron beam generated plasma in the forevacuum pressure range." MATEC Web of Conferences 143 (2018): 03008. http://dx.doi.org/10.1051/matecconf/201814303008.

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The paper presents research results of peculiarities of gas ion flows usage and their generation from large plasma formation (>50 sq.cm) obtained by electron beam ionization of gas in the forevacuum pressure range. An upgraded source was used for electron beam generation, which allowed obtaining ribbon electron beam with no transmitting magnetic field. Absence of magnetic field in the area of ion flow formation enables to obtain directed ion flows without distorting their trajectories. In this case, independent control of current and ion energy is possible. The influence of electron beam parameters on the parameters of beam plasma and ion flow – current energy and density – was determined. The results of alumina ceramics treatment with a beam plasma ions flow are given.

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Timofeev, A. V. "Flow of a plasma of multielectron elements along a magnetic field." Plasma Physics Reports 37, no. 11 (November 2011): 978–87. http://dx.doi.org/10.1134/s1063780x11100072.

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Moritaka, Toseo, Yasuhiro Kuramitsu, Yao-Li Liu, and Shih-Hung Chen. "Spontaneous focusing of plasma flow in a weak perpendicular magnetic field." Physics of Plasmas 23, no. 3 (March 2016): 032110. http://dx.doi.org/10.1063/1.4942028.

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32

Nakamura, R., D. N. Baker, D. H. Fairfield, D. G. Mitchell, R. L. McPherron, and E. W. Hones. "Plasma flow and magnetic field characteristics near the midtail neutral sheet." Journal of Geophysical Research 99, A12 (1994): 23591. http://dx.doi.org/10.1029/94ja02082.

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Ebersohn, Frans H., J. P. Sheehan, Alec D. Gallimore, and John V. Shebalin. "Kinetic simulation technique for plasma flow in strong external magnetic field." Journal of Computational Physics 351 (December 2017): 358–75. http://dx.doi.org/10.1016/j.jcp.2017.09.021.

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Kozlov, A. N. "Numerical Model of Plasma Flow Injection in a Solenoid’s Magnetic Field." Mathematical Models and Computer Simulations 13, no. 1 (January 2021): 1–10. http://dx.doi.org/10.1134/s2070048221010129.

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35

Shukurov, A., and D. D. Sokoloff. "Hydromagnetic Dynamo in Astrophysical Jets." Symposium - International Astronomical Union 157 (1993): 367–71. http://dx.doi.org/10.1017/s0074180900174431.

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The origin of a regular magnetic field in astrophysical jets is discussed. It is shown that jet plasma flow can generate a magnetic field provided the streamlines are helical. The dynamo of this type, known as the screw dynamo, generates magnetic fields with the dominant azimuthal wave number m = 1 whose field lines also have a helical shape. The field concentrates into a relatively thin cylindrical shell and its configuration is favorable for the collimation and confinement of the jet plasma.

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36

Vörös, Z., W. Baumjohann, R. Nakamura, A. Runov, T. L. Zhang, M. Volwerk, H. U. Eichelberger, et al. "Multi-scale magnetic field intermittence in the plasma sheet." Annales Geophysicae 21, no. 9 (September 30, 2003): 1955–64. http://dx.doi.org/10.5194/angeo-21-1955-2003.

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Abstract. This paper demonstrates that intermittent magnetic field fluctuations in the plasma sheet exhibit transitory, localized, and multi-scale features. We propose a multifractal-based algorithm, which quantifies intermittence on the basis of the statistical distribution of the "strength of burstiness", estimated within a sliding window. Interesting multi-scale phenomena observed by the Cluster spacecraft include large-scale motion of the current sheet and bursty bulk flow associated turbulence, interpreted as a cross-scale coupling (CSC) process.Key words. Magnetospheric physics (magnetotail; plasma sheet) – Space plasma physics (turbulence)

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37

Mikhailenko, V. S., D. V. Chibisov, and V. V. Mikhailenko. "Shear-flow-driven ion cyclotron instabilities of magnetic field-aligned flow of inhomogeneous plasma." Physics of Plasmas 13, no. 10 (October 2006): 102105. http://dx.doi.org/10.1063/1.2354021.

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38

Phan, T. D., and B. U. Ö. Sonnerup. "MHD stagnation-point flows at a current sheet including viscous and resistive effects: general two-dimensional solutions." Journal of Plasma Physics 44, no. 3 (December 1990): 525–46. http://dx.doi.org/10.1017/s0022377800015361.

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Exact solutions are presented of two-dimensional steady-state incompressible stagnation point flows at a current sheet separating two colliding plasmas. They describe the process of resistive field annihilation (zero reconnection) where the magnetic field in each plasma is strictly parallel to the current sheet, but may have different magnitudes and direction on its two sides. The flow in the (x, y) plane toward the current sheet, located at x = 0, may have an arbitrary angle of incidence and an arbitrary amount of divergence from or convergence towards the stagnation point. We find the most general form of the solution for the plasma velocity and for the magnetic field. For the z compenents of the flow and field, solutions in the form of truncating power series in y are found. The cases obtained in this study contain the solutions obtained by Parker, Sonnerup & Priest, Gratton et al. and Besser, Biernat & Rijnbeek as special cases. The role of viscosity in determining the flow and field configurations is examined. When the two colliding plasmas have the same viscosity and density, it is shown that viscous effects usually are important only in strongly divergent or convergent viscous flows with viscous Reynolds number of the order of unity or smaller. For astrophysical applications the viscous Reynolds number is usually high and the effects of viscosity on the interaction of plasmas of similar properties are small. The formulation of the stagnation-point flow problem involving plasmas of different properties is also presented. Sample cases of such flows are shown. Finally, a possible application of the results from this study to the earth's magnetopause is discussed briefly.

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ONO, Norifumi, Kazuhiro MUSHA, and Kazuo KOIKE. "Control of Plasma Jet Using Strong Magnetic Field." JSME International Journal Series B 48, no. 3 (2005): 411–16. http://dx.doi.org/10.1299/jsmeb.48.411.

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40

Myshkin, Vyacheslav F., Dmitry A. Izhoykin, Ivan A. Ushakov, and Viktor F. Shvetsov. "Physical and Chemical Processes Research of Isotope Separation in Plasma under Magnetic Field." Advanced Materials Research 880 (January 2014): 128–33. http://dx.doi.org/10.4028/www.scientific.net/amr.880.128.

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It is known that chemical bonding is only possible when particles with antiparallel valence electrons spins orientation collide [1, 2]. In an external magnetic field unpaired electrons spins precession around the field lines is observed. Precession frequencies of valence electrons of magnetic and nonmagnetic nuclei differ, resulting in a different probability to collide in reactive state for different isotopes. The investigations results of magnetic field influence on the carbon isotopes redistribution between carbon dioxide and disperse carbon in plasmachemical processes are given. Argon-oxygen plasma by a high-frequency generator was produced. Carbon placed into reaction zone by the high-frequency electrode evaporation. The plasmachemical reaction products quenching in the plasma flow at the sampler probe were examined. It is found that the Laval nozzle sampler is more efficient for plasma stream cooling versus the cylindrical sampler. The effects of flow rate, pressure and carbon dioxide concentration on the plasma flow cooling efficiency were estimated.

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41

Janhunen, P. "Simulation study of the plasma-brake effect." Annales Geophysicae 32, no. 10 (October 7, 2014): 1207–16. http://dx.doi.org/10.5194/angeo-32-1207-2014.

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Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

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42

Funaki, I., K. Ueno, H. Yamakawa, Y. Nakayama, T. Kimura, and H. Horisawa. "Interaction Between Plasma Flow and Magnetic Field in Scale Model Experiment of Magnetic Sail." Fusion Science and Technology 51, no. 2T (February 2007): 226–28. http://dx.doi.org/10.13182/fst07-a1357.

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Meng, Jian Bing, Xiao Juan Dong, and Chang Ning Ma. "Effects of External Transverse Alternating Magnetic Field on the Oscillating Amplitude of Atmospheric Pressure Plasma Arc." Advanced Materials Research 129-131 (August 2010): 692–96. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.692.

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A mathematical model was developed to describe the oscillating amplitude of the plasma arc injected transverse to an external transverse alternating magnetic field. The characteristic of plasma arc under the external transverse alternating magnetic field imposed perpendicular to the plasma current was discussed. The effect of processing parameters, such as flow rate of working gas, arc current, magnetic flux density and the standoff from the nozzle to the workpiece, on the oscillation of plasma arc were also analyzed. The results show that it is feasible to adjust the shape of the plasma arc by the transverse alternating magnetic field, which expands the region of plasma arc thermal treatment upon the workpiece. Furthermore, the oscillating amplitude of plasma arc decreases with decrease of the magnetic flux density. Under the same magnetic flux density, more gas flow rate, more arc current, and less standoff cause the oscillating amplitude to decrease. The researches have provided a deeper understanding of adjusting of plasma arc characteristics.

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Sumner, Chloe, and Youra Taroyan. "Amplification of magnetic field twisting by a stagnation point flow." Astronomy & Astrophysics 642 (October 2020): A181. http://dx.doi.org/10.1051/0004-6361/202038761.

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Context. Flows are a common feature of many processes occurring in the solar atmosphere, such as the formation of prominences where evaporated plasma from the chromosphere condensates along thin prominence threads that are seen to twist and oscillate. Aim. We aim to investigate the twisting of these threads by plasma condensation during their formation. Methods. We introduce a simple model with fixed critical points where the flow speed matches the Alfvén speed. This allows us to study the problem separately in the sub-Alfvénic and super-Alfvénic regimes. The temporal and spatial evolution of small amplitude initial twists along a thread is investigated analytically and numerically. Results. Analytical solutions are constructed in terms of the generalised hypergeometric functions. The solutions grow in time, despite the absence of any influxes of energy or magnetic fields. These results are confirmed numerically: We find oscillations with an amplifying amplitude and increasing period in the sub-Alfvénic regime. In the super-Alfvénic regime, we find twist amplification without any accompanying oscillations. An interesting result is the convergence of the twists at the critical points that leads to the formation of steep gradients and small scales. Energy is transferred from the flow to the amplifying twists. Conclusions. Magnetic field lines may be twisted by a stagnation point flow without the influx of any azimuthal field or energy. This twisting could assist in the formation of topology that is able to support the growth of prominences. The formation of steep gradients and small scales at the critical point is a new phenomenon which requires further investigation in the non-linear regime with the inclusion of magnetic diffusion.

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45

Burman, Ron. "Distorted Dipole Magnetic Fields." International Astronomical Union Colloquium 160 (1996): 433–34. http://dx.doi.org/10.1017/s0252921100042044.

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Mestel et al. (1985; MRΩ2) introduced an axisymmetric pulsar magnetosphere model in which electrons leave the star with non-negligible speeds and flow with moderate acceleration, and with poloidal motion that is closely tied to poloidal magnetic field lines, before reachingSL, a limiting surface near which rapid acceleration occurs. As well as these Class I flows, there exist Class II flows which do not encounter a region of rapid acceleration (Burman 1984, 1985b). The formalism introduced by MRΩ2to describe the moderately accelerated flows can be interpreted in terms of a plasma drift across the magnetic field, following injection along it (Burman 1985a).The MRΩ2formalism fully incorporates the toroidal magnetic field generated by the poloidal flow. The general formalism leaves the poloidal magnetic field unspecified, but, in the detailed development of MRΩ2, and in my papers, that field was taken to be the dipolar field of the star.Numerical work by Fitzpatrick & Mestel (1988a,b) suggested that the dipole approximation is inadequate. They developed a numerical technique for incorporating the modification to the poloidal magnetic field that is generated by the toroidal motions throughout the magnetosphere. They based their treatment on the hypothesis that those motions are such as to cancel the dipole field of the star, leaving a sextupole poloidal magnetic field at large distances.

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46

Iizuka, Satoru, Yasujiroh Minamitani, and Hiroshi Tanaca. "Particle and energy transport due to magnetic field-line reconnection in a tokamak." Journal of Plasma Physics 37, no. 3 (June 1987): 335–46. http://dx.doi.org/10.1017/s0022377800012228.

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Plasma behaviour during magnetic field-line reconnection which is driven by a rapid toroidal current reversal in a tokamak is investigated by calculating plasma flow speed from the magnetohydromatic equations with variables measured in the experiment. A strong plasma acceleration appears in the outside region of the X-type separatrix formed in the poloidal magnetic field lines. The induced electric field inside the plasma is evaluated directly from Ohm's law by using the fact that the toroidal current density vanishes during the current reversal. Then, plasma resistivity is estimated in the cross-section and the resulting value of energy flow is compared with that given by Poynting's theorem. It is found that the input energy is dissipated effectively through anomalous resistivity in the reconnection region.

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47

Longmore, M., S. J. Schwartz, and E. A. Lucek. "Rotation of the magnetic field in Earth's magnetosheath by bulk magnetosheath plasma flow." Annales Geophysicae 24, no. 1 (March 7, 2006): 339–54. http://dx.doi.org/10.5194/angeo-24-339-2006.

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Abstract. Orientations of the observed magnetic field in Earth's dayside magnetosheath are compared with the predicted field line-draping pattern from the Kobel and Flückiger static magnetic field model. A rotation of the overall magnetosheath draping pattern with respect to the model prediction is observed. For an earthward Parker spiral, the sense of the rotation is typically clockwise for northward IMF and anticlockwise for southward IMF. The rotation is consistent with an interpretation which considers the twisting of the magnetic field lines by the bulk plasma flow in the magnetosheath. Histogram distributions describing the differences between the observed and model magnetic field clock angles in the magnetosheath confirm the existence and sense of the rotation. A statistically significant mean value of the IMF rotation in the range 5°-30° is observed in all regions of the magnetosheath, for all IMF directions, although the associated standard deviation implies large uncertainty in the determination of an accurate value for the rotation. We discuss the role of field-flow coupling effects and dayside merging on field line draping in the magnetosheath in view of the evidence presented here and that which has previously been reported by Kaymaz et al. (1992).

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48

De Keyser, J., M. Echim, and M. Roth. "Cross-field flow and electric potential in a plasma slab." Annales Geophysicae 31, no. 8 (August 1, 2013): 1297–314. http://dx.doi.org/10.5194/angeo-31-1297-2013.

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Abstract. We consider cross-field plasma flow inside a field-aligned plasma slab embedded in a uniform background in a 1-dimensional geometry. This situation may arise, for instance, when long-lasting reconnection pulses inject plasma into the inner magnetosphere. The present paper presents a detailed analysis of the structure of the interfaces that separate the slab from the background plasma on either side; a fully kinetic model is used to do so. Since the velocity shear across both interfaces has opposite signs, and given the typical gyroradius differences between injected and background ions and electrons, the structure of both interfaces can be very different. The behaviour of the slab and its interfaces depends critically on the flow of the plasma transverse to the magnetic field; in particular, it is shown that there are bounds to the flow speed that can be supported by the magnetised plasma. Further complicating the picture is the effect of the potential difference between the slab and its environment.

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Moawad, S. M. "Exact equilibria for nonlinear force-free magnetic fields with its applications to astrophysics and fusion plasmas." Journal of Plasma Physics 80, no. 2 (January 15, 2014): 173–95. http://dx.doi.org/10.1017/s0022377813001050.

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AbstractKnowledge of the structure of coronal magnetic field originating from the photosphere is relevant to the understanding of many solar activity phenomena, e.g. flares, solar prominences, coronal loops, and coronal heating. In most of the existing literature, these loop-like magnetic structures are modeled as force-free magnetic fields (FFMF) without any plasma flow. In this paper, we present several exact solution classes for nonlinear FFMF, in both translational and axisymmetric geometries. The solutions are considered for their possible relevance to astrophysics and solar physics problems. These are used to illustrate arcade-type magnetic field structures of the photosphere and twisted magnetic flux ropes through the coronal mass ejections (CMEs), as well as magnetic confinement fusion plasmas.

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Potemra, T. A., M. J. Engebretson, L. J. Zanetti, R. E. Erlandson, and P. F. Bythrow. "Satellite observations of currents and waves in space plasmas." Laser and Particle Beams 6, no. 3 (August 1988): 503–11. http://dx.doi.org/10.1017/s0263034600005425.

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When viewed from outer space, the earth's magnetic field does not resemble a simple dipole, but is severely distorted into a comet-shaped configuration by the continuous flow of solar wind plasma. A complicated system of currents flows within this distorted magnetic field configuration called the ‘magnetosphere’ (See figure 1). For example, the compression of the geomagnetic field by the solar wind on the dayside of the earth is associated with a large-scale current flowing across the geomagnetic field lines, called the ‘Chapman-Ferraro’ or magnetopause current. The magnetospheric system includes large-scale currents that flow in the ‘tail’, the ring current that flows at high altitudes around the equator of the earth, field-aligned ‘Birkeland’ currents that flow along geomagnetic field lines into and away from the two auroral regions, and a complex system of currents that flows completely within the layers of the ionosphere, the earth's ionized atmosphere. The intensities of these various currents reach millions of amperes and are closely related to solar activity. The geomagnetic field lines can also oscillate, like giant vibrating strings, at specified resonant frequencies. The effects of these vibrations, sometimes described as ‘standing Alfvén waves’, have been observed on the ground in magnetic field recordings dating back to the beginning of the century. Observations of currents and waves with satellite-borne magnetic field experiments have provided a new perspective on the complicated plasma processes that occur in the magnetosphere. Some of the new observations are described here.

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Journal articles on the topic 'Plasma flow in magnetic field'

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