scholarly journals Beam instabilities in a magnetized pair plasma

1999 ◽  
Vol 62 (1) ◽  
pp. 65-86 ◽  
Author(s):  
MAXIM LYUTIKOV
Keyword(s):  
Growth Rates ◽  
Particle Interaction ◽  
Kinetic Regime ◽  
Pulsar Magnetosphere ◽  
Pair Plasma ◽  
Electron Positron ◽  
Pulsar Radiation ◽  
Radiation Generation ◽  
Field Lines ◽  
Beam Instabilities

Beam instabilities in the strongly magnetized electron–positron plasma of a pulsar magnetosphere are considered. We analyse the resonance conditions and estimate the growth rates of the Cherenkov and cyclotron instabilities of the ordinary (O), extraordinary (X) and Alfvén modes in two limiting regimes: kinetic and hydrodynamic. The importance of the different instabilities as a source of coherent pulsar radiation generation is then estimated, taking into account the angular dependence of the growth rates and the limitations on the length of the coherent wave–particle interaction imposed by the curvature of the magnetic field lines. We conclude that in the pulsar magnetosphere, Cherenkov-type instabilities occur in the hydrodynamic regime, while cyclotron-type instabilities occur in the kinetic regime. We argue that electromagnetic cyclotron-type instabilities on the X, O and probably Alfvén waves are more likely to develop in the pulsar magnetosphere.

scholarly journals Alfvén resonance absorption in electron-positron plasmas

2010 ◽  
Vol 6 (S274) ◽  
pp. 224-227 ◽  
Author(s):  
N. F. Cramer
Keyword(s):  
Mode Conversion ◽  
Alfven Wave ◽  
Pulsar Magnetosphere ◽  
Pulsar Radio ◽  
Inertial Alfvén Wave ◽  
Pair Plasma ◽  
Electron Positron ◽  
Normal Electron ◽  
The Magnetic Field ◽  
Pulsar Radio Emission

AbstractWaves propagating obliquely in a magnetized cold pair plasma experience an approximate resonance in the wavevector component perpendicular to the magnetic field, which is the analogue of the Alfvén resonance in normal electron-ion plasmas. Wave absorption at the resonance can take place via mode conversion to the analogue of the short wavelength inertial Alfvén wave. The Alfvén resonance could play a role in wave propagation in the pulsar magnetosphere leading to pulsar radio emission. Ducting of waves in strong plasma gradients may occur in the pulsar magnetosphere, which leads to the consideration of Alfvén surface waves, whose energy is concentrated in the region of strong gradients.

The scaling of collisionless magnetic reconnection in an electron–positron plasma with non-scalar pressure

2012 ◽  
Vol 79 (5) ◽  
pp. 473-477 ◽  
Author(s):  
M. HOSSEINPOUR ◽  
M. A. MOHAMMADI ◽  
S. BIABANI
Keyword(s):  
Magnetic Reconnection ◽  
Skin Depth ◽  
Larmor Radius ◽  
Anisotropic Pressure ◽  
Diffusion Region ◽  
Pair Plasma ◽  
Tearing Instability ◽  
Electron Positron ◽  
Sheet Width ◽  
Field Lines

AbstractCollisionless magnetic reconnection via tearing instability in non-relativistic electron–positron (pair) plasma with an anisotropic pressure is investigated. The equilibrium magnetic field is considered to be sheared force-free, and a set of linearized collisionless Magnetohydrodynamics equations describes the evolution of reconnection dynamics. A linear analytical analysis, based on scaling, demonstrates that in such a pair plasma, breaking the frozen in flow constraint for field lines can be mainly provided by the non-gyrotropic pressure of electrons and positrons (rather than the particle bulk inertia) when the current sheet width is smaller than the particle Larmor radius (Δx < rL). This condition is satisfied when β > d2 (d = c/ωp is the particle skin-depth with the electron/positron frequency ωp and β = 8πP(0)/B02 ⪡ 1). Meanwhile, on top of the Lorentz force and in the absence of the reconnection facilitating mechanism of the Hall effect, non-scalar pressure force can accelerate bulk plasma into the diffusion region at the scale lengths of the order of dx. Therefore, the respective regime of tearing instability proceeds much faster compared with the case of an isotropic pressure with a new dimensionless growth rate of (γτA) ~ d.

scholarly journals Resonant Effect of High-Energy Electron–Positron Pairs Production in Collision of Ultrarelativistic Electrons with an X-ray Electromagnetic Wave

Universe ◽  
2021 ◽  
Vol 7 (7) ◽  
pp. 210
Author(s):  
Georgii K. Sizykh ◽  
Sergei P. Roshchupkin ◽  
Victor V. Dubov
Keyword(s):  
High Energy ◽  
Energy Electron ◽  
Opening Angle ◽  
High Energy Electron ◽  
Scattered Electron ◽  
Differential Probability ◽  
X Ray ◽  
Electron Positron ◽  
Pulsar Radiation ◽  
Resonant Effect

The process of resonant high-energy electron–positron pairs production by electrons in an X-ray pulsar electromagnetic field is studied theoretically. Under the resonance conditions, the second-order process under consideration effectively reduces into two sequential first-order processes: X-ray-stimulated Compton effect and X-ray–stimulated Breit–Wheeler process. The kinematics of the process is studied in detail: the dependencies of the energy of the scattered electron on its outgoing angle and the energies of the particles of the pair on the outgoing angle of the scattered electron and the opening angle of the pair are obtained. The analysis of the number of different possible particles energies values in the entire range of the angles is also carried out, according to which the energies of the particles of the pair can take up to eight different values at a fixed outgoing angle of the scattered electron and opening angle of the pair. The estimate of the resonant differential probability per unit time of the process, which reaches the maximum value of 24 orders of the value of the non-resonant differential probability per unit time, is obtained. The angular distribution of the differential probability per unit time of the process is analyzed, particularly for the case of high-energy positrons presenting in pulsar radiation.

scholarly journals Electron Outflow in Axisymmetric Pulsar Magnetospheres

1985 ◽  
Vol 38 (5) ◽  
pp. 749 ◽  
Author(s):  
RR Burman
Keyword(s):  
Magnetic Field ◽  
Pulsar Magnetosphere ◽  
Poloidal Magnetic Field ◽  
Light Cylinder ◽  
Field Lines ◽  
Limiting Surface

Mestel et al. (1985) have recently introduced an axisymmetric pulsar magnetosphere model in which electrons leave the star with speeds that are non-negligible, but not highly relativistic, and flow with moderate acceleration, and with poloidal motion that is closely tied to the poloidal magnetic field lines, before reaching a limiting surface, near which rapid acceleration occurs. This paper presents an analysis of flows which either encounter the limiting surface beyond the light cylinder or do not meet it at all.

scholarly journals Wave propagation in pulsar magnetospheres

2012 ◽  
Vol 8 (S291) ◽  
pp. 540-542
Author(s):  
Chen Wang ◽  
Dong Lai ◽  
Jinlin Han
Keyword(s):  
Radio Waves ◽  
Plasma Parameters ◽  
Electron Positron ◽  
Transfer Equations ◽  
Propagation Effects ◽  
Consistent Manner ◽  
Physical Effects ◽  
Field Lines ◽  
Polarization Profiles ◽  
The Magnetic Field

AbstractWe study the propagation effects of radio waves in a pulsar magnetosphere, composed of relativistic electron-positron pair plasmas streaming along the magnetic field lines and corotating with the pulsar. We critically examine the various physical effects that can potentially influence the observed wave intensity and polarization. We numerically integrate the transfer equations for wave polarization in the rotating magnetosphere, taking account of all the propagation effects in a self-consistent manner. For typical magnetospheric plasma parameters produced by pair cascade, we find that the observed radio intensity and polarization profiles can be strongly modified by the propagation effects. Some applications of our results are discussed.

scholarly journals Progress Towards a Laser Produced Relativistic Electron-Positron Pair Plasma

2016 ◽  
Vol 688 ◽  
pp. 012010 ◽  
Author(s):  
Hui Chen ◽  
J. Bonlie ◽  
R. Cauble ◽  
F. Fiuza ◽  
W. Goldstein ◽  
...  
Keyword(s):  
Relativistic Electron ◽  
Pair Plasma ◽  
Electron Positron ◽  
Electron Positron Pair

scholarly journals Modes of Energy Loss from Isolated Magnetized Neutron Star

1987 ◽  
Vol 125 ◽  
pp. 450-450
Author(s):  
S. Shibata
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Gamma Ray ◽  
Rotational Energy ◽  
Pair Creation ◽  
Dipole Radiation ◽  
Pair Plasma ◽  
Electron Positron ◽  
Closed Current ◽  
Electron Positron Pair

Pulsar may be regarded as a discharge tube by electron-positron pair creation. On this viewpoint we carry out two numerical calculations. The obtained magnetic field is consistent with the flow. We find that pulsars emit their rotational energy through three modes simultaneously. The three modes are (1)relativistic acceleration and following gamma-ray emission in the closed current circuit in the magnetosphere, (2)wind of the electron-positron pair plasma, and (3)dipole radiation.

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