Superstrong Magnetic Field Research Articles

Angular dependence of coherent radio emission from magnetars with multipolar magnetic fields

ABSTRACT The recent detection of a fast radio burst (FRB) from a Galactic magnetar secured the fact that neutron stars (NSs) with superstrong magnetic fields are capable of producing these extremely bright coherent radio bursts. One of the leading mechanisms to explain the origin of such coherent radio emission is the curvature radiation process within the dipolar magnetic field structure. It has, however, already been demonstrated that magnetars likely have a more complex magnetic field topology. Here, we critically investigate curvature radio emission in the presence of inclined dipolar and quadrupolar (‘quadrudipolar’) magnetic fields and show that such field structures differ in their angular characteristics from a purely dipolar case. We analytically show that the shape of open field lines can be modified significantly depending on both the ratio of quadrupole to dipole field strength and their inclination angle at the NS surface. This creates multiple points along each magnetic field line that coincide with the observer’s line of sight, and may explain the complex spectral and temporal structure of the observed FRBs. We also find that in quadrudipole, the radio beam can take a wider angular range and the beamwidth can be wider than that in pure dipole. This may explain why the pulse width of the transient radio pulsation from magnetars is as large as that of ordinary radio pulsars.

Macroscale fast flow and magnetic-field generation in two-temperature relativistic electron–ion plasmas of astrophysical objects

We have shown the simultaneous generation of macro-scale fast flows and strong magnetic fields in the 2-temperature relativistic electron-ion plasmas of astrophysical objects due to Unified Reverse Dynamo/Dynamo mechanism. The resulting dynamical magnetic field amplification and/or flow acceleration is directly proportional to the initial turbulent kinetic/magnetic (magnetic) energy; the process is very sensitive to relativistically hot electron-ion fraction temperature and magneto-fluid coupling. It is shown, that for realistic physical parameters of White Dwarfs accreting hot astrophysical flow / Binary systems there always exists such a real solution of dispersion relation for which the formation of dispersive strong super-Alfv\'enic macro-scale flow/outflow with Alfv\'en Mach number $> 10^6$ and/or generation of super-strong magnetic fields is guaranteed.

Iron group nuclei electron capture in super-Chandrasekhar superstrong magnetic white dwarfs

Using the theory of relativistic mean-field effective interactions, the influences of superstrong magnetic fields (SMFs) on electron Fermi energy, binding energy per nucleus and single-particle level structure are discussed in super-Chandrasekhar magnetic white dwarfs. Based on the relativistical SMFs theory model of Potekhin et al., the electron chemical potential is corrected in SMFs, and the electron capture (EC) of iron group nuclei is investigated by using the Shell-Model Monte Carlo method and Random Phase Approximation theory. The EC rates can increase by more than three orders of magnitude due to the increase of the electron Fermi energy and the change of single-particle level structure by SMFs. However, the EC rates can decrease by more than four orders of magnitude due to increase of the nuclei binding energy by SMFs. We compare our results with those of FFNs (Fuller et al.), AUFDs (Aufderheide et al.) and Nabi (Nabi et al.). Our rates are higher by about four orders of magnitude than those of FFN, AUFD and Nabi due to SMFs. Our study may have important reference value for subsequent studies of the instability, mass radius relationship, and thermal and magnetic evolution of super-Chandrasekhar magnetic white dwarfs.

Formation of dense plasma on the surface of a stainless steel conductor in superstrong magnetic fields

In experiments on the GIT-12 megaampere generator, the characteristics of conductors made of AISI 321 stainless steel were investigated in the microsecond regime of increasing superstrong magnetic fields. In this regime, a skin explosion of the conductor material takes place with the formation of a dense plasma and its expansion into the interelectrode gap of the vacuum transmission line. The values of the characteristic magnetic field B0 = 100 T are determined, above which there is the effect of nonlinear diffusion of the magnetic field into the conductor, and the critical magnetic field BCT ≅ 260 T, the excess of which leads to the formation of dense plasma on the surface of the massive conductor. A method is proposed for increasing the critical magnetic field on the surface of a conductor up to 1.5 times by choosing the optimal thickness of the conducting surface, and criteria for its determination are given. The effect of increasing the critical magnetic field on the surface of a two-layer sample and creating a pressure in the Mbar range until the moment of formation and expansion of explosion products of an inner conductor with high conductivity has been tested.

Instability Due to Electron Captures of Nuclei 56Ni, 56Co, 56Fe, 56Mn, 56Cr, and 56V in Strongly Magnetized Super-Chandrasekhar White Dwarfs

Based on the theory of the relativistic mean-field effective interactions, we explore the effect of superstrong magnetic fields (SMFs) on nuclear single-particle level structure, nuclear blinding energy, and the electron Fermi energy in strongly magnetized super-Chandrasekhar white dwarfs (SMSWDs). We also discuss the electron capture (EC) instability from the threshold mass density (TMD) and threshold pressure (TP) for some typical iron group nuclei in SMSWD due to SMFs. At relatively low densities (e.g., ρ 7 = 57, 97, 197), the EC rates increase and they then decrease by more than four orders of magnitude. However, at relatively higher density (e.g., ρ 7 = 4197), the rates increase by about two orders of magnitude when 2 × 103 < B 12 < 5 × 104, and then the SMFs have a minor effect on EC rates. The TMD (TP) can increase by about 23% ∼ 29%, due to an increase in the electron–ion interaction and nuclear binding energy in SMFs. As SMFs further increase, the TMD (TP) increase almost linearly for one Landau levels system. For a two and three Landau level system, the SMFs have a slight influence on the TMD (TP) (e.g., at B 12 = 103.5), and then TMD (TP) increases by about 13% ∼ 14%, and finally decreases by about 27.85% (27.34%). The shift of the onset of EC can make the maximum mass of the SMSWD increase by more than 2.28% for a one Landau level system. This influence from TMD (TP) can be larger than that of general relativity for SMSWD, which contains some iron group nuclei.

Use of powerful shock and detonation waves to study extreme states of matter* *The paper was written on the basis of a report presented by R I Il’kaev on January 10, 2003 at the plenary session of the International Scientific Conference, The Nuclear Age: Science and Society, dedicated to the 100th anniversary of the birth of Igor’ Vasil’evich Kurchatov. The

This article is written on the basis of a report given 10 January 2003 at the International Scientific Conference, The Nuclear Age: Science and Society, dedicated to the 100th anniversary of the birth of Igor’Vasil’evich Kurchatov. It presents the results of work on the experimental study of substance properties under high pressure shock waves, briefly describes the use of super-strong magnetic fields for the study of substances at high pressure, presents the results of computational and theoretical research methods, and presents some results of studies of substance properties using liner systems in high-power pulsed electrophysical facilities (VNIIEF disk explosion-magnetic generators and USA Pegasus and ATLAS capacitor banks).

Studying Cosmic Ray Sources Using Intergalactic Electromagnetic Cascades

In this paper, intergalactic electromagnetic cascades are used as a probe of cosmic ray sources. This is achieved as follows. In extragalactic space, cosmic rays initiate electromagnetic cascades, in which gamma-ray and neutrino emission arises. We used the joint analysis of cosmic ray data, along with extragalactic gamma-ray and neutrino emissions, to study particle acceleration in the vicinity of supermassive black holes. Particle injection spectra depend on processes of particle acceleration, and here we discuss models with various injection spectra. The computations of the propagation of cosmic rays in space were performed using the publicly available TransportCR code. It was found that a new subclass of sources might exist that does not contribute to the particle flux on Earth, instead to gamma-ray and neutrino emissions arising in electromagnetic cascades. In addition, the upper limit of the relative number of ‘exotic’ supermassive black holes surrounded by a superstrong magnetic field is derived.

New insight into the physical essence of pulsar glitch

Based on the oscillation between the B phase and A phase of 3P2 neutron superfluid in neutron stars, we propose a new glitch model for young pulsars. According to our model, the glitch is explained as a repeat phenomena from the quasi period 3P2 neutron superfluid B phase, to A phase, then to B phase (many repeated glitches with quasi-period). With the repeating of the phase transition, the vortex quantum number of 3P2 neutron superfluid vortices is gradually reduced, and the heating rate ε(B) in B phase also gets lower and lower. After a number of glitches, the time intervals between successive glitches will gradually become longer, and the glitch amplitude decreases. When the heating rate ε(B) of an old neutron star becomes lower than the cooling rate of the direct Urca, which can happen in a super-strongmagnetic field, the B phase of the 3P2 neutron superfluid vortices is no longer returned to the A phase state and the phase oscillation of the system is stopped immediately. The slowing glitch phenomenon of some older pulsars is a natural result of our theory, which means that very old pulsars will no longer present the glitch. Our model will be tested in future pulsar glitch observations.

Generation of superstrong quasi-stationary magnetic fields in laser cluster plasma

An analytical model has been developed for the generation of a superstrong quasi-stationary magnetic field (up to several GG) in the focal waist of an ultra-intense short circularly polarised laser pulse interacting with a gas-cluster target. The rotation of relativistic electrons around the ionised core of the cluster has been shown to produce a magnetic moment and a quasi-stationary magnetic field. With a large number of nanoclusters, the magnetic field occupies the entire focal volume with a characteristic spatial scale of tens of micrometers and exists during the cluster expansion time (i.e., several picoseconds).

A Cosmic Zevatron Based on Cyclotron Auto-resonance

Abstract A Zevatron is an accelerator scheme envisaged to accelerate particles to ZeV energies (1 ZeV = 1021 eV). Schemes, most notably the internal shock model, have been proposed to explain the acceleration of ultra-high-energy cosmic-ray particles that have been sporadically detected reaching Earth since 1962. Here, the cyclotron auto-resonance acceleration (CARA) mechanism is tailored and used to demonstrate the possible acceleration of particles ejected as a result of violent astrophysical processes such as the merger of a binary system or a supernova explosion. Such events result in emission of highly energetic particles and ultra-intense beamed radiation. In the simultaneous presence of a super-strong magnetic field, the condition for cyclotron auto-resonance may be met. Thus CARA can act like a booster for particles pre-accelerated inside their progenitor by shock waves, possibly among other means. As examples, it is shown that nuclei of hydrogen, helium, and iron-56, may reach ZeV energies by CARA, under which conditions the particles, while gyrating around the lines of an ultra-strong magnetic field, also surf on the waves of a super-intense radiation field. When radiation-reaction is taken into account, it is shown that the ZeV energy gained by a particle can fall off by less than an order of -magnitude if the resonance condition is missed by roughly less than 20%.

Концептуальная модель квазибессилового магнита малого объема c инерционным удержанием его торцевой части

The efficiency of using a diamagnetic screen with inertial retention in a non-destructive quasi-force-free magnet of a small volume (with a characteristic dimension about 10 cm^3 ) for generating a superstrong magnetic field with a pulse duration of about 10 µs is shown. A configuration of the magnet was developed, in which the end part of the winding is balanced due to the fact that the screen virtually does not move during the discharge. Mechanical stresses in the winding were calculated, and it was demonstrated that mechanical strength of the winding can be ensured in a field with magnetic flux density up to 100T. Calculations of the heating of the winding were performed and the possibilities of its reduction to an acceptable level are indicated.

Novel features of magnetization in weakly ionized neutron star

In order to investigate the structural properties of strongly magnetized neutron star (NS), we have followed the Landau magnetization approach of quantized, degenerate electrons to obtain a new expression of the magnetization M, in the presence of super strong magnetic field B . It is shown that the susceptibility is positive square root function of B, hence the associated permeability (μ) will be than 1. Next, the conceptual issue regarding the impact of magnetization M on Maxwell-quantum magneto hydrodynamic (QMHD) equations is addressed, the obtained modified QMHD model is followed to investigate the dispersive properties of low frequency waves in weakly ionized plasma, consisting of degenerate neutrons, electrons and ions in the atmosphere of degenerate NS. The dispersion relation of a new type of magnetosonic waves propagating perpendicular to the B field is obtained in the presence of quantized magnetic pressure, with Alfven speed being reduced by the factor μ. It is shown that magnetar flares may excite new type of Alfvén waves propagating along the B field, Alfven frequency is found to have only decreasing trend with the increase of μ, to depict that the surface-crust of NS are magnetized enough to contain a quantum ‘ordered superconducting fluid. Moreover, the Alfven speed, calculated here, is found to be function of neutron mass density in contrast to the usual electron ion plasma case. We suggest an experimental search for Alfven-like waves in superconductors.

Formation of superstrong horizontal magnetic field in delta-type sunspot in radiation magnetohydrodynamic simulations

ABSTRACT We perform a series of radiative magnetohydrodynamic simulations to understand the amplification mechanism of the exceptionally strong horizontal magnetic field in delta-type sunspots. In the simulations, we succeed in reproducing the delta-type sunspot and resulting strong magnetic field exceeding 6000 G in a light bridge between the positive and negative polarities. Our conclusions in this study are summarized as follows: (1) The essential amplification mechanism of the strong horizontal magnetic field is the shear motion caused by the rotation of two spots. (2) The strong horizontal magnetic field remains the force-free state. (3) The peak strength of the magnetic fields does not depend on the spatial resolution, top boundary condition, or Alfvén speed limit. The origin of the rotating motion is rooted in the deep convection zone. Therefore, the magnetic field in the delta-spot light bridge can be amplified to the superequipartition values in the photosphere.

Solid Helium as a Nontraditional Energy Source

The results of quantum-chemical calculations of helium atoms in strong and superstrong magnetic fields are described. The calculations showed the possibility of transferring helium atoms to superstable states with the release of a huge amount of energy, provided that helium was previously converted to a solid state at a sufficiently high pressure and low temperature. In addition to energy production, the possibility of using helium as a coherent radiation source, that is, as a laser with a predetermined frequency.

Generation and modulation of terahertz gradient force in the interactions of two-color laser pulses with magnetized plasmas

Terahertz (THz) waves, as far-infrared light, offer new opportunities for the optical trapping and manipulation of single cells, in contrast to the other light sources. We present an efficient scheme to flexibly control multiple THz field distribution patterns generated by the laser–plasma interaction in a magnetized plasma. An analytical THz radiation field and two-dimensional particle-in-cell simulation are constructed to verify the feasibility of the scheme. Modulation of the THz gradient force and the energy flux by an asymmetrical THz field is investigated for the purpose of trapping and manipulating particles and cells. In particular, the stabilities of flexibly controlled THz radiation are investigated carefully in the form of the strong and short laser and super-strong magnetic field induced significant spatial structure instabilities and frequency instabilities of terahertz radiation.

Concept Design of the Tritium Plant on the TRINITI Site for the Tokamak Ignitor Project Tasks

The tokamak Ignitor project is one of the main topics of long-term scientific cooperation between the Russian Federation and the Italian Republic. The tokamak Ignitor has a super-strong magnetic field (13 T) and a powerful discharge current (11 MA for 10 s). Ohmic heating is the main mechanism for the ignition of the fusion reaction.The location of the tokamak Ignitor on the Russian side has been proposed to be the complex Tokamak with Strong Field (TSP complex), which is located on the JSC “SRC RF TRINITI” (TRINITI) Joint Stock Company – State Research Center of Russian Federation Troitsk Institute for Innovation and Fusion Research site (Moscow, Troitsk, Russia). The TSP complex has unique engineering and physical and energy infrastructure, but it will be necessary to deeply modernize the infrastructure.In the phase of the deuterium-tritium experiments on the tokamak Ignitor, providing a total tritium flow of 10 to 15 g/day will be required. Therefore, it is necessary to consider the development of a full-scale tritium complex with the entire set of solved tasks for the preparation and supply of the fuel mixture, the purification of the plasma exhaust products, and the separation of the isotopes.

МАГНІТНІ ПОЛЯ У ЛІМБОВИХ СОНЯЧНИХ СПАЛАХАХ НА ВИСОТАХ 2–14 Мм

We present the results of observations of two powerful limb solar flares which occured on 17 July 1981 and 14 July 2005. Spectral observations of these flares were carried out with the Echelle spectrograph of the Horizontal Solar Telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. In order to measure the magnetic fields in these flares, I ± V profiles of К СаІІ, HeI 4471.5 and Нα lines were studied. It was found that effective (averaged) magnetic field Вeff in the flares reached 1100–3000 G on heights 2–14 Mm. However, the spectral evidences to yet stronger fields of ~ 104 G range were found. In particular, the weak spectral evidences of large Zeeman splitting were found in first flare by HeI 4471.5 line; this evidences corresponds to superstrong magnetic field of 15.5 kG. In the second flare, Нα line has non-parallelism of bisectors of I ± V profiles which can reflect existence of 1550–3000 G fields in the flare. However, in frame of simple two-component model these observed values can correspond to true local (amplitude) magnetic fields Вmax in range 4.65–18 kG. Apparently, such superstrong magnetic fields arise in structures of a force-free type, with strong twisting of the field lines. It is precisely such field values that are necessary in solar flares for energy reasons. Indeed, solar flares emit energy in the range of 1027-1032 erg in a volume of the order of 1027 cm3. Elementary calculations show that in order to provide such energy in such a volume, the magnetic field strength should be at least 103 G. In addition, if we take into account that solar magnetic fields have the sub-telescopic (spatially unresolved) structure, then the local magnetic field intensities in the flares at the coronal level can be expected even higher.

Atomic effects in astrophysical nuclear fusion reactions

The electron-screening acceleration of laboratory fusion reactions at astrophysical' energies is an unsolved problem of great importance to astrophysics. That effect is modeled here by considering the fusion of hydrogen-like atoms whose electron probability density is used in Poisson 's equation in order to derive the corresponding screened Coulomb potential energy. That way atomic excitations and deformations of the fusing atoms can be taken into account. Those potentials are then treated semiclassically in order to obtain the screening (accelerating) factor of the reaction. By means of the proposed model the effect of a superstrong magnetic field on laboratory Hydrogen fusion reactions is investigated here for the first time showing that, despite the considerable increase in the cross section of the dd reaction, the pp reaction is still too slow to justify experimentation. The proposed model is finally applied on the H2 (d, p) H3 fusion reaction describing satisfactorily the experimental data although some ambiguity remains regarding the molecular nature of the deuteron target. Notably, the present method gives a sufficiently high screening energy for Hydrogen fusion reactions so that the take-away energy of the spectator nucleus can also be taken into account.

Superstrong photospheric magnetic fields in sunspot penumbrae

Context. Recently, there have been some reports of unusually strong photospheric magnetic fields (which can reach values of over 7 kG) inferred from Hinode SOT/SP sunspot observations within penumbral regions. These superstrong penumbral fields are even larger than the strongest umbral fields on record and appear to be associated with supersonic downflows. The finding of such fields has been controversial since they seem to show up only when spatially coupled inversions are performed. Aims. Here, we investigate and discuss the reliability of those findings by studying in detail observed spectra associated with particularly strong magnetic fields at the inner edge of the penumbra of active region 10930. Methods. We applied classical diagnostic methods and various inversions with different model atmospheres to the observed Stokes profiles in two selected pixels with superstrong magnetic fields, and compared the results with a magnetohydrodynamic simulation of a sunspot whose penumbra contains localized regions with strong fields (nearly 5 kG at τ = 1) associated with supersonic downflows. Results. The different inversions provide different results: while the SPINOR 2D inversions consider a height-dependent single-component model and return B &gt; 7 kG and supersonic positive vLOS (corresponding to a counter-Evershed flow), height-dependent two-component inversions suggest the presence of an umbral component (almost at rest) with field strengths ∼4 − 4.2 kG and a penumbral component with vLOS ∼ 16 − 18 km s−1 and field strengths up to ∼5.8 kG. Likewise, height-independent two-component inversions find a solution for an umbral component and a strongly redshifted (vLOS ∼ 15 − 17 km s−1) penumbral component with B ∼ 4 kG. According to a Bayesian information criterion, the inversions providing a better balance between the quality of the fits and the number of free parameters considered by the models are the height-independent two-component inversions, but they lie only slightly above the SPINOR 2D inversions. Since it is expected that the physical parameters all display considerable gradients with height, as supported by magnetohydrodynamic (MHD) sunspot simulations, the SPINOR 2D inversions are the preferred ones. Conclusions. According to the MHD sunspot simulation analyzed here, the presence of counter-Evershed flows in the photospheric penumbra can lead to the necessary conditions for the observation of ∼5 kG fields at the inner penumbra. Although a definite conclusion about the potential existence of fields in excess of 7 kG cannot be given, their nature could be explained (based on the simulation results) as the consequence of the extreme dynamical effects introduced by highly supersonic counter-Evershed flows (vLOS &gt; 10 km s−1 and up to ∼30 km s−1 according to SPINOR 2D). The latter are much faster and more compressive downflows than those found in the MHD simulations and therefore could lead to field intensification up to considerably stronger fields. Also, a lower gas density would lead to a deeper depression of the τ = 1 surface, making possible the observation of deeper-lying stronger fields. The superstrong magnetic fields are expected to be nearly force-free, meaning that they can attain much larger strengths than expected when considering only balance between magnetic pressure and the local gas pressure.

EVIDENCES FOR STRONG MIXED-POLARITY MAGNETIC FIELDS IN AREA OF A SEISMIC SOURCE ASSOCIATED WITH LARGE PROTON SOLAR FLARE

We present in a concise statement the new results based on spectral-polarization measurements of magnetic fields in an extremely powerful proton solar flare on October 28, 2003 of X17.2 / 4B class. The observation material was obtained with Echelle spectrograph of HST AO KNU, which makes it possible to analyze the spectral manifestations of the Zeeman effect in very many lines of the visible region of the spectrum, including the photospheric and chromospheric lines. The I ± V and V profiles of about ten FeI and FeII lines, as well as the Hα, Hβ, Hγ, and Hδ lines were studied in a area of the seismic source of the flare, which was localized in the sunspot penumbra of S magnetic polarity. In this flare, we found an unprecedented Balmer decrement of intensities of Hα and Hβ lines which corresponds to ratio I (Hβ) / I (Hα) = 1.68. In the FeI 5434.5 line with very low Lande factor (g eff = –0.014), a reliable splitting of emission peaks was found, which could indicate superstrong magnetic fields (about 50 kG) of N polarity. Indications for magnetic fields with intensity ≈ 12 kG of S polarity were found too. These indications are based on the study of the Stokes V profile of FeII 5234.6 line. In this line, there were two positive and two negative peaks of profile V, indicating a two- component structure of the magnetic field. According to the simulation data, the small-scale component with the above-mentioned superstrong magnetic field had a filling factor about 0.1 and had narrow (about twice) the half- widths of the line profiles. The close contact of subtelescopic magnetic fields of different magnetic polarity, but of lower intensity (B ≈ 1 kG) was also indicated by the comparison of the half-widths of the FeI 5247.1 and 5250.2 lines. In general, it can be concluded that the necessary conditions for the reconnection of magnetic lines were fulfilled even at the photospheric level, rather than in the corona or chromosphere, as suggested by theoretical models of solar flares.