The influence of azimuthal motion on ion resonance instability for a non-neutral plasma column

1995 ◽  
Vol 54 (2) ◽  
pp. 173-183 ◽  
Author(s):  
H. C. Chen
Keyword(s):  
Plasma Column ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Maxwell Model ◽  
Threshold Value ◽  
General Treatment ◽  
Plasma Rotation ◽  
Rotational Equilibrium ◽  
Neutral Plasma ◽  
Fast Ion

A general treatment of ion resonance instability for a non-neutral plasma column is performed using a macroscopic cold-fluid-Maxwell model. The azimuthal motion of the plasma components has an important influence on the behaviour of the instability. When the electrons are in slow rotational equilibrium, the instability occurs in both slow and fast ion rotational equilibrium. However, there is stability when the electrons are in fast rotational equilibrium except that the l = 1 mode becomes unstable and independent of plasma rotation. The kink (l = 1) mode only occurs when the plasma column boundary exceeds a certain threshold value that depends on the ratio of the plasma frequency to the cyclotron frequency.

scholarly journals Electron acceleration by whistler pulse in high-density plasma

2017 ◽  
Vol 35 (3) ◽  
pp. 386-390
Author(s):  
A.K. Singh
Keyword(s):  
Cyclotron Frequency ◽  
Ponderomotive Force ◽  
Plasma Frequency ◽  
Threshold Value ◽  
High Density ◽  
Quantum Plasma ◽  
Quantum Hydrodynamic Model ◽  
Threshold Amplitude ◽  
Dirac Distribution ◽  
Quantum Hydrodynamic

AbstractThe acceleration of an electron by the ponderomotive force of a Gaussian whistler pulse in a magnetized high-density quantum plasma obeying Fermi–Dirac distribution is studied using the recently developed quantum hydrodynamic model. Effective acceleration takes place when the peak whistler amplitude exceeds a threshold value, and the whistler frequency is greater than the cyclotron frequency. The threshold amplitude decreases with ratio of plasma frequency to electron cyclotron frequency. The electron is accelerated at velocities of about twice the group velocity of the whistler.

Coupling of Upper Hybrid Surface Plasmon Modes in Magnetoplasma Waveguide Structure

2021 ◽  
Vol 14 (2) ◽  
pp. 155-160
Keyword(s):  
High Frequency ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Single Mode ◽  
Homogeneous System ◽  
Slab Waveguide ◽  
Surface Modes ◽  
Plasma Slab ◽  
Warm Plasma ◽  
Hybrid Waves

Abstract: We investigate the spectra of high-frequency electrostatic surface electron plasmon oscillations propagating normal to a dc-magnetic field. These oscillations are supported by two identical magnetoplasma slabs separated by a vacuum slab. Propagation characteristics of surface magnetoplasma oscillations and their coupling are studied by simultaneously solving the homogeneous system of equations obtained by matching the electrostatic fields at the interfaces together with the warm plasma dielectric function of upper hybrid waves. We demonstrate the existence of two propagating magnetoplasma electrostatic surface modes (backward and forward modes). The backward mode emerges at frequency ω=ω_uh=√(ω_pe^2+ω_ce^2 ), where ω_pe and ω_ce are the electron plasma frequency and the electron cyclotron frequency, respectivily, and the forward propagating mode emerges at a lower frequency ω=ω_uh-ω_pe. The forward and backward surface modes become coupled and form a single mode at upper hybrid resonance quasi-static value ω=ω_uh/√2. Keywords: Upper hybrid modes, Plasma slab waveguide, Coupled plasmon surface modes.

scholarly journals Novel internal measurements of ion cyclotron frequency range fast-ion driven modes

2021 ◽  
Author(s):  
Neal A Crocker ◽  
Shawn X Tang ◽  
Kathreen E Thome ◽  
Jeff Lestz ◽  
Elena Belova ◽  
...  
Keyword(s):  
Cyclotron Frequency ◽  
Harmonic Wave ◽  
Wave Number ◽  
Frequency Range ◽  
High Wave Number ◽  
Minor Radius ◽  
Ion Cyclotron ◽  
Cyclotron Emission ◽  
Edge Localized Modes ◽  
Fast Ion

Abstract Novel internal measurements and analysis of ion cyclotron frequency range fast-ion driven modes in DIII-D are presented. Observations, including internal density fluctuation (ñ) measurements obtained via Doppler Backscattering, are presented for modes at low harmonics of the ion cyclotron frequency localized in the edge. The measurements indicate that these waves, identified as coherent Ion Cyclotron Emission (ICE), have high wave number, _⊥ρ_fast ≳ 1, consistent with the cyclotron harmonic wave branch of the magnetoacoustic cyclotron instability (MCI), or electrostatic instability mechanisms. Measurements show extended spatial structure (at least ~ 1/6 the minor radius). These edge ICE modes undergo amplitude modulation correlated with edge localized modes (ELM) that is qualitatively consistent with expectations for ELM-induced fast-ion transport.

THE ADMITTANCE OF AN INFINITE CYLINDRICAL ANTENNA IN A LOSSY INCOMPRESSIBLE, ANISOTROPIC PLASMA

1967 ◽  
Vol 45 (12) ◽  
pp. 4019-4038 ◽  
Author(s):  
Edmund K. Miller
Keyword(s):  
Magnetic Field ◽  
Free Space ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Floating Potential ◽  
Space Layer ◽  
Cylindrical Antenna ◽  
Warm Plasma ◽  
Positive Ion ◽  
Uniform Plasma

A numerical investigation of the admittance of an infinite, circular cylindrical antenna excited at a circumferential gap of nonzero thickness, and immersed in a lossy incompressible magnetoplasma with the antenna parallel to the static magnetic field is described. A concentric free-space layer (the vacuum sheath) which separates the antenna from the external uniform plasma is included in the analysis to approximate the positive ion sheath which may form about a body at floating potential in a warm plasma. The numerical results for the antenna admittance show that: (1) in the absence of a sheath, a sharp admittance maximum is found at the electron cyclotron frequency, with the maximum more pronounced when the plasma frequency exceeds the cyclotron frequency than for the converse case; (2) the vacuum sheath shifts upward in frequency and reduces in amplitude the admittance maximum which occurs for the sheathless case at the cyclotron frequency; (3) a kink or minimum in the admittance is found at the plasma frequency.

Rayleigh surface waves along the boundary between a plasma and a metallic screen

1993 ◽  
Vol 49 (2) ◽  
pp. 227-235 ◽  
Author(s):  
S. T. Ivanov ◽  
K. M. Ivanova ◽  
E. G. Alexov
Keyword(s):  
Wave Propagation ◽  
Electromagnetic Wave ◽  
Surface Waves ◽  
Electromagnetic Waves ◽  
Electromagnetic Wave Propagation ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Magnetoactive Plasma ◽  
Rayleigh Surface Waves ◽  
The Waves

Electromagnetic wave propagation along the interface between a magnetoactive plasma and a metallic screen is investigated analytically and numerically. It is shown that the waves have a Rayleigh character: they are superpositions of two partial waves. It is concluded that electromagnetic waves propagate only at frequencies lower than min (ωp, ωc), where ωpis the plasma frequency and ωcis the cyclotron frequency. The field topology is found, and the physical character of the waves is discussed.

Magnetic stabilization of transverse plasma instabilitiest

1971 ◽  
Vol 5 (3) ◽  
pp. 467-474 ◽  
Author(s):  
B. Buti ◽  
G. S. Lakhina
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Electron Plasma ◽  
Wave Number ◽  
Uniform External Magnetic Field ◽  
Magnetic Stabilization ◽  
Streaming Velocity ◽  
The Magnetic Field

Waves, propagating transverse to the direction of the streaming of a plasma in the presence of a uniform external magnetic field, are unstable if the streaming exceeds a certain minimum value. The magnetic field reduces the growth rate of this instability, and also increases the value of the minimum streaming velocity, above which the system is unstable. The thermal motions in the plasma, however, tend to stabilize the system if the magnetic field is weak (i.e. , Ω being the electron cyclotron frequency, k the characteristic wave-number, and Vt the thermal velocity); but, in case of strong magnetic field (i.e. ), they increase the growth rate, provided (ωp being the electron plasma frequency).

The admittance of an infinite cylindrical antenna in a lossy, compressible, anisotropic plasma

1968 ◽  
Vol 46 (9) ◽  
pp. 1109-1118 ◽  
Author(s):  
Edmund K. Miller
Keyword(s):  
Plasma Parameter ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Fourier Integral ◽  
Dipole Antenna ◽  
Cylindrical Antenna ◽  
Axis Parallel ◽  
E Region ◽  
Antenna Surface ◽  
Parameter Values

An analysis of the current on an infinite cylindrical dipole antenna which is excited across a circumferential gap of nonzero thickness and immersed in a lossy, compressible magnetoplasma with its axis parallel to the static magnetic field is described. Some numerical results are presented for the antenna admittance for the sheathless case, where the uniform magnetoplasma is in contact with the antenna surface. The admittance values are obtained from a numerical integration of the Fourier integral for the antenna current, and are given for plasma parameter values typical of the E region of the ionosphere.The admittance values obtained exhibit a maximum slightly above the electron cyclotron frequency, and in this regard are similar to the admittance when the magnetoplasma is incompressible but separated from the antenna by a free-space layer (the vacuum sheath). In addition, the admittance is found to have a slight minimum at the plasma frequency and to have a more pronounced minimum at the upper hybrid frequency where also the susceptance changes sign, these minima not being significantly affected by the plasma compressibility or vacuum sheath. These features of the calculated admittances are found to have a qualitative resemblance to experimental results obtained from antenna measurements in the ionosphere.

HF heating of a plasma column at frequencies below the electron cyclotron frequency

1978 ◽  
Vol 28 (10) ◽  
pp. 1093-1100 ◽  
Author(s):  
J. Ďatlov ◽  
V. Kopecký ◽  
J. Musil ◽  
F. Žáček ◽  
K. Novik
Keyword(s):  
Plasma Column ◽  
Cyclotron Frequency ◽  
Electron Cyclotron ◽  
Electron Cyclotron Frequency ◽  
Hf Heating
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