scholarly journals Fast magnetic energy dissipation in relativistic plasma induced by high order laser modes

2016 ◽  
Vol 4 ◽  
Author(s):  
Y. J. Gu ◽  
Q. Yu ◽  
O. Klimo ◽  
T. Zh. Esirkepov ◽  
S. V. Bulanov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Energy ◽  
Collisionless Plasma ◽  
High Energy ◽  
Field Energy ◽  
Displacement Current ◽  
Particle In Cell ◽  
Magnetic Field Energy ◽  
High Energy Electrons

Fast magnetic field annihilation in a collisionless plasma is induced by using TEM(1,0) laser pulse. The magnetic quadrupole structure formation, expansion and annihilation stages are demonstrated with 2.5-dimensional particle-in-cell simulations. The magnetic field energy is converted to the electric field and accelerate the particles inside the annihilation plane. A bunch of high energy electrons moving backwards is detected in the current sheet. The strong displacement current is the dominant contribution which induces the longitudinal inductive electric field.

scholarly journals Slowing the spins of stellar cores

2019 ◽  
Vol 485 (3) ◽  
pp. 3661-3680 ◽  
Author(s):  
Jim Fuller ◽  
Anthony L Piro ◽  
Adam S Jermyn
Keyword(s):  
Magnetic Field ◽  
Magnetic Energy ◽  
Compact Objects ◽  
Field Energy ◽  
Red Giants ◽  
Turbulent Dissipation ◽  
Rotation Rates ◽  
Magnetic Field Energy ◽  
Rotational Evolution ◽  
Red Giant

ABSTRACT The angular momentum (AM) evolution of stellar interiors, along with the resulting rotation rates of stellar remnants, remains poorly understood. Asteroseismic measurements of red giant stars reveal that their cores rotate much faster than their surfaces, but much slower than theoretically predicted, indicating an unidentified source of AM transport operates in their radiative cores. Motivated by this, we investigate the magnetic Tayler instability and argue that it saturates when turbulent dissipation of the perturbed magnetic field energy is equal to magnetic energy generation via winding. This leads to larger magnetic field amplitudes, more efficient AM transport, and smaller shears than predicted by the classic Tayler–Spruit dynamo. We provide prescriptions for the effective AM diffusivity and incorporate them into numerical stellar models, finding they largely reproduce (1) the nearly rigid rotation of the Sun and main sequence stars, (2) the core rotation rates of low-mass red giants during hydrogen shell and helium burning, and (3) the rotation rates of white dwarfs. We discuss implications for stellar rotational evolution, internal rotation profiles, rotational mixing, and the spins of compact objects.

scholarly journals Turbulent dynamo in a collisionless plasma

2016 ◽  
Vol 113 (15) ◽  
pp. 3950-3953 ◽  
Author(s):  
François Rincon ◽  
Francesco Califano ◽  
Alexander A. Schekochihin ◽  
Francesco Valentini
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Energy ◽  
Collisionless Plasma ◽  
High Energy ◽  
Nearby Galaxy ◽  
Astrophysical Plasmas ◽  
Flow Energy ◽  
Field Amplification ◽  
Turbulent Dynamo

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.

scholarly journals Magnetic Field Energy Harvesting with a Lead-Free Piezoelectric High Energy Conversion Material

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1346
Author(s):  
Quan Wang ◽  
Kyung-Bum Kim ◽  
Sang Bum Woo ◽  
Tae Hyun Sung
Keyword(s):  
Magnetic Field ◽  
Energy Conversion ◽  
High Performance ◽  
High Energy ◽  
Green Energy ◽  
Lead Free ◽  
Field Energy ◽  
Energy Harvesters ◽  
Magnetic Field Energy ◽  
Piezoelectric Energy

This article presents a high-performance lead-free piezoelectric energy harvester (LPEH) system for magnetic field. It based on a Ba0.85Ca0.15Ti0.90Zr0.10O3 + CuO 0.3 wt% (BCTZC0.3) composite was fabricated by sintering at 1450 °C. The BCTZC0.3 composite, which has an enhanced high energy conversion constant (), shows improved piezoelectric power-generation performance when compared with conventional piezoelectric energy harvesters. The BCTZC0.3-based LPEH produces instantaneous maximum power of 8.2 mW and an energy density of 107.9 mW/cm3 in a weak magnetic field of 250 μT. This system can be used to charge a capacitor and operate a wireless sensor network (WSN) system to provide temperature sensing and radio-frequency (RF) transmission in a 250 μT magnetic field. The proposed LPEH is a promising green-energy device for potentially self-powering WSN systems when applied.

scholarly journals Magnetic field annihilation and charged particle acceleration in ultra-relativistic laser plasmas

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan-Jun Gu ◽  
Sergei V. Bulanov
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Laser Plasma ◽  
Large Scale ◽  
Rapid Development ◽  
Collisionless Plasma ◽  
Basic Mechanism ◽  
Field Energy ◽  
Plasma Interactions ◽  
Magnetic Field Energy

Abstract Magnetic reconnection driven by laser plasma interactions attracts great interests in the recent decades. Motivated by the rapid development of the laser technology, the ultra strong magnetic field generated by the laser-plasma accelerated electrons provides unique environment to investigate the relativistic magnetic field annihilation and reconnection. It opens a new way for understanding relativistic regimes of fast magnetic field dissipation particularly in space plasmas, where the large scale magnetic field energy is converted to the energy of the nonthermal charged particles. Here we review the recent results in relativistic magnetic reconnection based on the laser and collisionless plasma interactions. The basic mechanism and the theoretical model are discussed. Several proposed experimental setups for relativistic reconnection research are presented.

scholarly journals Magnetic Field Energy Harvesting with a Lead-Free Piezoelectric High Energy Conversion Material

2021 ◽  
Author(s):  
Tae Hyun Sung ◽  
QUAN WANG ◽  
Kyung Bum Kim ◽  
Sang Bum Woo
Keyword(s):  
Magnetic Field ◽  
Energy Conversion ◽  
High Performance ◽  
Energy Harvester ◽  
High Energy ◽  
Green Energy ◽  
Lead Free ◽  
Field Energy ◽  
Magnetic Field Energy ◽  
Piezoelectric Energy

A high-performance Lead-free Piezoelectric Energy Harvester (LPEH) based on a Ba0.85Ca0.15Ti0.90Zr0.10O3 + CuO 0.3 wt% (BCTZC0.3) composite was fabricated by sintering at 1450℃. The BCTZC0.3 composite, which has an enhanced high-energy-conversion constant (〖d_33×g〗_33), shows improved piezoelectric power-generation performance when compared with conventional piezoelectric energy harvesters. The BCTZC0.3-based LPEH produces instantaneous maximum power of 8.2 mW and an energy density of 107.9 mW/cm3 in a weak magnetic field of 250 μT. This energy harvester can be used to charge a capacitor and operate a wireless sensor network (WSN) system to provide temperature sensing and radio-frequency (RF) transmission in a 250 μT magnetic field. The proposed LPEH is a promising green-energy device for potentially self-powering WSN systems when applied.

A confident source of hard X-rays: radiation from a tokamak applicable for runaway electrons diagnosis

2016 ◽  
Vol 23 (5) ◽  
pp. 1227-1231 ◽  
Author(s):  
M. Kafi ◽  
A. Salar Elahi ◽  
M. Ghoranneviss ◽  
M. R. Ghanbari ◽  
M. K. Salem
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Energy ◽  
Toroidal Magnetic Field ◽  
Vacuum Vessel ◽  
X Rays ◽  
Runaway Electrons ◽  
High Energy Electrons ◽  
High Loop ◽  
The Mean

In a tokamak with a toroidal electric field, electrons that exceed the critical velocity are freely accelerated and can reach very high energies. These so-called `runaway electrons' can cause severe damage to the vacuum vessel and are a dangerous source of hard X-rays. Here the effect of toroidal electric and magnetic field changes on the characteristics of runaway electrons is reported. A possible technique for runaways diagnosis is the detection of hard X-ray radiation; for this purpose, a scintillator (NaI) was used. Because of the high loop voltage at the beginning of a plasma, this investigation was carried out on toroidal electric field changes in the first 5 ms interval from the beginning of the plasma. In addition, the toroidal magnetic field was monitored for the whole discharge time. The results indicate that with increasing toroidal electric field the mean energy of runaway electrons rises, and also an increase in the toroidal magnetic field can result in a decrease in intensity of magnetohydrodynamic oscillations which means that for both conditions more of these high-energy electrons will be generated.

scholarly journals Estimating the magnetic energy inside traveling compression regions

2009 ◽  
Vol 27 (5) ◽  
pp. 1969-1978 ◽  
Author(s):  
S. A. Kiehas ◽  
V. S. Semenov ◽  
H. K. Biernat ◽  
V. V. Ivanova ◽  
R. Nakamura ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Kinetic Energy ◽  
Theoretical Result ◽  
Magnetic Energy ◽  
Field Energy ◽  
Plasma Energy ◽  
Magnetic Field Energy ◽  
The Magnetic Field

Abstract. We investigate a series of six TCRs (traveling compression regions), appearing in the course of a small substorm on 19 September 2001. Except for two of these TCRs, all Cluster spacecraft were located in the lobe and detected the typical signatures of TCRs, i.e., compressions in |B| and bipolar Bz variations. We use these perturbations in Bz for calculations on the magnetic energy inside the TCR and compare the amount of magnetic field energy with the kinetic energy inside the underlying plasma bulge. According to results obtained from theory, the amount of magnetic energy inside TCRs is about two times higher than the kinetic plasma energy inside the accompanied plasma bulge. We verify this theoretical result by first investigations of the magnetic field energy inside TCRs. The calculations lead to a magnetic energy in the order of 1010 Joule per RE for each of the TCRs.

COOLING OF RELATIVISTIC ELECTRONS IN TEV BLAZARS: CLUES FROM MULTIWAVELENGTH SPECTRA

2008 ◽  
Vol 17 (09) ◽  
pp. 1591-1601
Author(s):  
R. SCHLICKEISER
Keyword(s):  
Magnetic Field ◽  
Energy Density ◽  
Kinetic Energy ◽  
High Energy ◽  
Particle Energy ◽  
Field Energy ◽  
Kinetic Energy Density ◽  
Relativistic Electrons ◽  
Magnetic Field Energy ◽  
The Magnetic Field

In powerful cosmic nonthermal radiation sources with dominant magnetic-field self generation, the generation of magnetic fields at almost equipartition strength by relativistic plasma instabilities operates as fast as the acceleration or injection of ultra-high energy radiating electrons and hadrons in these sources. Consequently, the magnetic field strength becomes time-dependent and adjusts itself to the actual kinetic energy density of the radiating electrons in these sources. This coupling of the magnetic field and the magnetic field energy density to the kinetic energy of the radiating particles changes both the intrinsic temporal evolution of the relativistic particle energy spectrum after injection and the synchrotron and synchrotron self-Compton emissivities.

scholarly journals Generation and decay of the magnetic field in collisionless shocks

2016 ◽  
Vol 12 (S324) ◽  
pp. 62-65
Author(s):  
Mikhail Garasev ◽  
Evgeny Derishev
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Field Energy ◽  
Magnetic Field Generation ◽  
Collisionless Shocks ◽  
Particle In Cell ◽  
Magnetic Field Energy ◽  
Relativistic Shocks ◽  
Continuous Injection ◽  
The Magnetic Field

AbstractWe present the results of numerical particle-in-cell (PIC) simulations of the magnetic field generation and decay in the upstream of collisionless shocks. We use the model, where the magnetic field in the incoming flow is generated by continuous injection of anisotropic electron-positron pairs. We found that the continuous injection of anisotropic plasma in the upstream of the shock-wave generates the large-scale, slowly decaying magnetic field that is later amplified during the passage of the shock front. In our simulations the magnetic field energy reached ~0.01 of the equipartition value, after that it slowly decays on the time scale proportional to the duration of the injection in the upstream. Thus, the magnetic field survives for a sufficiently long time, and supports efficient synchrotron radiation from relativistic shocks, e.g., in GRBs.

scholarly journals Formation of electron clouds during particle acceleration in a 3D current sheet

2010 ◽  
Vol 6 (S274) ◽  
pp. 453-457 ◽  
Author(s):  
Valentina V. Zharkova ◽  
Taras Siversky
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Spatial Separation ◽  
High Energy ◽  
X Ray ◽  
Particle In Cell ◽  
High Energy Electrons ◽  
Sufficient Energy ◽  
Electron Clouds ◽  
The Magnetic Field

AbstractAcceleration of protons and electrons in a reconnecting current sheet (RCS) is investigated with the test particle and particle-in-cell (PIC) approaches in the 3D magnetic configuration including the guiding field. PIC simulations confirm a spatial separation of electrons and protons towards the midplane and reveal that this separation occur as long as protons are getting accelerated. During this time electrons are ejected into their semispace of the current sheet moving away from the midplane to distances up to a factor of 103 – 104 of the RCS thickness and returning back to the RCS. This process of electron circulation around the current sheet midplane creates a cloud of high energy electrons around the current sheet which exists as long as protons are accelerated. Only after protons gain sufficient energy to break from the magnetic field of the RCS, they are ejected to the opposite semispace dragging accelerated electrons with them. These clouds can be the reason of hard X-ray emission in coronal sources observed by RHESSI.

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