scholarly journals Ordinary electromagnetic mode instability

1975 ◽  
Vol 13 (2) ◽  
pp. 335-348 ◽  
Author(s):  
Chio-Zong Cheng
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Velocity Distribution ◽  
Growth Rates ◽  
Cyclotron Frequency ◽  
Single Species ◽  
Dispersion Characteristics ◽  
Mode Instability ◽  
Plasma Parameters ◽  
Electromagnetic Mode

The instability of the ordinary electromagnetic mode, propagating perpendicular to an external magnetic field, is studied for a single-species plasma with ring velocity distribution. The marginal instability boundaries for both the purely growing mode and the propagating growing modes are calculated from the instability criteria. The dispersion characteristics for various sets of plasma parameters are also given. The frequency bands of the propagating growing modes are centered at about (η +½)ωc, where η = 1, 2,…, and the typical growth rates are of the order of the cyclotron frequency and enhanced by increasing fluβ1.

Influence of dispersion on the modulational instability of a whistler wave

1989 ◽  
Vol 41 (2) ◽  
pp. 289-300 ◽  
Author(s):  
V. I. Karpman ◽  
A. G. Shagalov
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Growth Rates ◽  
Cyclotron Frequency ◽  
Modulational Instability ◽  
Low Frequency ◽  
Whistler Wave ◽  
Long Wave ◽  
Frequency Modulations ◽  
Magnetic Sound

The modulational instability of a whistler wave propagating along an external magnetic field is investigated, taking into account the dispersion of the low-frequency modulations. The dispersive effects are significant if the modulation frequencies Ω are comparable to or greater than the ion cyclotron frequency ωci. It is shown that in this case there are four unstable branches: the long-wave modulational instability and three others with much larger growth rates. At Ω≪ωci the latter correspond to fast magnetic sound, Alfvén and slow magnetic sound branches.

Ordinary-mode electromagnetic instabifity for counter-streaming ions with anisotropic temperatures

1973 ◽  
Vol 9 (1) ◽  
pp. 17-21 ◽  
Author(s):  
J. D. Gaffey ◽  
W. B. Thompson ◽  
C. S Liu
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
External Magnetic Field ◽  
Cyclotron Frequency ◽  
Ion Beams ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Electromagnetic Mode ◽  
Necessary And Sufficient ◽  
The Magnetic Field

The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is investigated for two ion beams with anisotropic temperatures, counter-streaming along the magnetic field. A necessary and sufficient condition for instability is derived. The growth rate is calculated, and found to be typically several times the ion cyclotron frequency Ωi, although in extreme cases γmax may be as large as (Mi/me)½Ωi.

Plasma parameters in a twin-chamber RF inductive plasma source, placed in a weak external magnetic field

Vacuum ◽  
2019 ◽  
Vol 169 ◽  
pp. 108927 ◽  
Author(s):  
A.K. Petrov ◽  
E.A. Kralkina ◽  
A.M. Nikonov ◽  
K.V. Vavilin ◽  
I.I. Zadiriev
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Plasma Source ◽  
Plasma Parameters

scholarly journals HIGH-CURRENT RELATIVISTIC ELECTRON BEAM FOCUSING IN PLASMA

2021 ◽  
pp. 30-34
Author(s):  
О.V. Manuilenko ◽  
A.V. Pashchenko ◽  
V.G. Svichensky ◽  
B.V. Zajtsev
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
External Magnetic Field ◽  
Relativistic Electron ◽  
Relativistic Electron Beam ◽  
Beam Current ◽  
High Current ◽  
Plasma Parameters ◽  
Beam Focusing ◽  
Envelope Equation

The analysis of the envelope equation for high-current relativistic electron beam propagation in plasma in an external uniform magnetic field is presented. The envelope equation is obtained in a Hamiltonian form with an effective potential, which depends from electron beam and plasma parameters, and external magnetic field. Hamiltonian aproach allows fully analyze the behavior of the beam envelope as a function of the beam current, beam energy, plasma density and conductivity, as well as on the external magnetic field and the initial beam angular momentum.

scholarly journals Weibel instability in a plasma with nonzero external magnetic field

2012 ◽  
Vol 30 (7) ◽  
pp. 1051-1054 ◽  
Author(s):  
O. A. Pokhotelov ◽  
M. A. Balikhin
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Dispersion Relation ◽  
External Magnetic Field ◽  
Linear Growth ◽  
Cyclotron Frequency ◽  
Linear Growth Rate ◽  
Temperature Anisotropy ◽  
Formal Similarity ◽  
Weibel Instability

Abstract. The theory of the Weibel instability is generalized for the case of a plasma immersed in a nonzero external magnetic field. It is shown that the presence of this external field modifies the dispersion relation for this mode which now possesses a nonzero frequency. The explicit expression for the real and imaginary parts of the frequency is then calculated. It turns out that the linear growth rate remains unchanged, whereas the frequency becomes nonzero due to the finite value of the electron cyclotron frequency. The frequency of the Weibel mode is found to be proportional to the electron temperature anisotropy. The formal similarity of the Weibel and drift-mirror instabilities is outlined.

Equilibrium configurations of Vlasov plasmas carrying a current component along an external magnetic field

1972 ◽  
Vol 7 (3) ◽  
pp. 445-459 ◽  
Author(s):  
J. R. Kan
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
External Magnetic Field ◽  
Constant Field ◽  
Current Component ◽  
Equilibrium Solutions ◽  
Plasma Parameters ◽  
Equilibrium Configurations ◽  
Field Aligned Current ◽  
A Current

A class of equilibrium configurations of Vlasov plasmas carrying a current component along an external magnetic field is presented. The present slab model contains the diamagnetic current jy, and the field-aligned current jz for arbitrary βc (= particle pressure/magnetic pressure of the applied constant field). For fixed βc and field-aligned current, our model admits a family of equilibrium solutions in which the diamagnetic currents range from zero to a maximum value. The amount of diamagnetic current flowing in a machine depends on the width of the machine, the field-aligned current and other plasma parameters. The Helmholtz free energy of the system is calculated under the constraints that the total number of particles and the field-aligned current are conserved. The least unstable equilibrium configuration in a machine is obtained by minimizing the free energy under the stated constraints among all equilibria whose plasma widths do not exceed the width of the machine.

New kinetic cyclotron instability for electron beam in time-changing magnetic fields

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
Irena Vorgul ◽  
M. Ayling ◽  
C. R. Straub ◽  
D. M. MacKay ◽  
J. D. Houghton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Cyclotron Resonance ◽  
Cyclotron Frequency ◽  
Resonance Condition ◽  
Velocity Distribution Function ◽  
Spatial Gradient ◽  
Total Change ◽  
The Magnetic Field

This paper examines the velocity distribution function and cyclotron resonance conditions for a beam of electrons moving in a magnetic field which gradually changes with time. A spatial gradient of magnetic field is known to result in an unstable horseshoe distribution of electrons. The field gradient in time adds additional effects due to an induced electric field. The resultant anisotropic velocity distribution function, which we call a Luvdisk distribution, has some distinctive properties when compared to the horseshoe. Fitting the cyclotron resonance condition circle shows that the frequency of the resultant emission is under the local cyclotron frequency. While the spatial gradient results in the emission coming almost perpendicularly to the field, the direction of the radiation under a time-changing field has more variability. The Luvdisk distribution also arises when the magnetic field has a gradient both in space and time. The beam can be unstable if those gradients are added or subtracted from each other (if the gradients are of equal or different sign), which occurs even when the total change of magnetic field is negative. While the frequency of the emission is related to the final magnetic field value, its direction is indicative of the field’s history which produced the instability.

Ordinary-mode electromagnetic instability for counter-streaming plasmas with anisotropic temperatures

1972 ◽  
Vol 7 (2) ◽  
pp. 189-206 ◽  
Author(s):  
J. D. Gaffey ◽  
W. B. Thompson ◽  
C. S. Liu
Keyword(s):  
Growth Rates ◽  
Cyclotron Frequency ◽  
Temperature Anisotropy ◽  
Electromagnetic Mode ◽  
Large Growth ◽  
Streaming Velocity ◽  
Frequency Comparison ◽  
Necessary And Sufficient ◽  
Stream Instability ◽  
Electromagnetic Instability

The instability of the ordinary electromagnetic mode propagating perpendicular to an external magnetic field is studied for two counter-streaming plasmas with anisotropic temperatures. A necessary and sufficient condition for this instability is derived and the growth rate is calculated. Although instability can occur in a plasma with low β‖e, provided the streaming velocity is comparable to the parallel electron thermal velocity, β‖e of the order of unity and large electron temperature anisotropy (T‖e≫ T⊥e) are required for large growth rates. These large growth rates are typically of the order of the electron cyclotron frequency. Comparison with the electrostatic two-stream instability is made.

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