The absorption mechanism of the ordinary mode propagating perpendicularly to the magnetic field at the electron cyclotron frequency

1982 ◽  
Vol 25 (9) ◽  
pp. 1605 ◽  
Author(s):  
R. A. Cairns
Keyword(s):  
Magnetic Field ◽  
Cyclotron Frequency ◽  
Electron Cyclotron ◽  
Absorption Mechanism ◽  
Ordinary Mode ◽  
Electron Cyclotron Frequency ◽  
The Magnetic Field

Inhomogeneity effects on the absorption of electromagnetic high-frequency waves by magnetized Maxwellian plasmas

1990 ◽  
Vol 43 (3) ◽  
pp. 335-356 ◽  
Author(s):  
R. A. Caldela Fo ◽  
R. S. Schneider ◽  
L. F. Ziebell
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Electromagnetic Waves ◽  
Cyclotron Frequency ◽  
Electron Cyclotron ◽  
Temperature Anisotropy ◽  
Plasma Parameters ◽  
Electron Cyclotron Frequency ◽  
High Frequency Waves ◽  
The Magnetic Field

Inhomogeneity effects on the absorption of high-frequency electromagnetic waves by magnetized Maxwellian plasmas are considered, and in particular the propagation and absorption of the ordinary and extraordinary modes propagating perpendicularly to the magnetic field are analysed. We show that, for small values of the ratio of the electron plasma frequency to the electron-cyclotron frequency, the inhomogeneity effects are more important for the ordinary mode, and that for values of this ratio close to or greater than unity the effects become pronounced for the extraordinary mode. It is also shown that, for a given value of this ratio, and for a fixed value of the ratio of electron-cyclotron frequency to wave frequency, the inhomogeneity effects tend to increase as the ambient magnetic field decreases. The temperature dependence of the effect, the dependence on the direction of propagation l'elative to the inhomogeneity, the influence of temperature anisotropy, and the isolated contribution of the gradients of different plasma parameters are investigated. Several circumstances in which instabilities may occur are mentioned.

scholarly journals Excitation of chorus with small wave normal angles due to BPA mechanism into density ducts

2019 ◽  
Author(s):  
Peter A. Bespalov ◽  
Olga N. Savina
Keyword(s):  
Magnetic Field ◽  
Cyclotron Frequency ◽  
Angular Spectrum ◽  
Electron Cyclotron ◽  
Electron Cyclotron Frequency ◽  
Proposed Model ◽  
Small Wave ◽  
Pulse Amplifier ◽  
Wave Normal ◽  
The Magnetic Field

Abstract. We examine specific features of the realization of the beam pulse amplifier mechanism (BPA) of chorus excitation in the density ducts having a width of the order of 100–300 km with refractive reflection. The dispersion characteristics of whistler emissions in a planar duct under conditions for the fulfillment of the WKB approximation and refractive reflection from the walls of the duct are analyzed. It is shown that in the enhanced duct, discrete spectral elements of chorus with a narrow angular spectrum along the external magnetic field can be excited at frequencies somewhat lower than half the electron cyclotron frequency. In the depleted duct at frequencies somewhat higher than half the electron cyclotron frequency chorus with a narrow angular spectrum along the magnetic field can be excited. The proposed model explains the possibility of excitation of chorus with small angles of the wave normal when the BPA mechanism is implemented. It is noted that the properties of chorus, such as the intensity and a typical angle of the wave normal, can be different for the lower and upper band chorus.

scholarly journals Excitation of chorus with small wave normal angles due to beam pulse amplifier (BPA) mechanism in density ducts

2019 ◽  
Vol 37 (5) ◽  
pp. 819-824
Author(s):  
Peter A. Bespalov ◽  
Olga N. Savina
Keyword(s):  
Magnetic Field ◽  
Cyclotron Frequency ◽  
Angular Spectrum ◽  
Electron Cyclotron ◽  
Electron Cyclotron Frequency ◽  
Proposed Model ◽  
Small Wave ◽  
Pulse Amplifier ◽  
Wave Normal ◽  
The Magnetic Field

Abstract. We examine specific features of the realisation of the beam pulse amplifier (BPA) mechanism of chorus excitation in the density ducts that have a width of the order of 100–300 km with refractive reflection. The dispersion characteristics of whistler emissions in a planar duct under conditions for the fulfilment of the Wentzel–Kramers–Brillouin (WKB) approximation and refractive reflection from the “walls” of the duct are analysed. It is shown that in the enhanced duct, discrete spectral elements of chorus with a narrow angular spectrum along the external magnetic field can be excited at frequencies somewhat lower than half of the electron cyclotron frequency. In the depleted duct at frequencies somewhat higher than half of the electron cyclotron frequency, chorus with a narrow angular spectrum along the magnetic field can be excited. The proposed model explains the possibility of excitation of chorus with small angles of the wave normal when the BPA mechanism is implemented. It is noted that the properties of chorus, such as the intensity and a typical angle of the wave normal, can be different for the lower- and upper-band chorus.

The magnetic moment of the proton II. The value in Bohr magnetons

1963 ◽  
Vol 272 (1348) ◽  
pp. 103-118 ◽  
Keyword(s):  
Magnetic Field ◽  
Resonance Frequency ◽  
Magnetic Moment ◽  
Cyclotron Frequency ◽  
Electron Cyclotron ◽  
Proton Spin ◽  
Radio Frequency Field ◽  
Electron Cyclotron Frequency ◽  
True Value ◽  
Spin Resonance

The magnetic moment of the proton has been measured in Bohr magnetons by comparing the proton spin-resonance frequency with the electron cyclotron frequency in the same magnetic field. The electron cyclotron signal was observed as an absorption of energy from a radio-frequency field in a cavity. Particular attention was paid to the elimination of effects which might have altered the electron cyclotron frequency from the true value. The result, related to the spin-resonance frequency of the free proton, is that the magnetic moment of the proton is (1.521043 ± 0.000006) x 10 -4 Bohr magneton.

scholarly journals Plasma Waves Near the Electron Cyclotron Frequency in the Near Sun Solar Wind: Wave Mode Identification and Driving Instabilities

2021 ◽  
Author(s):  
David Malaspina ◽  
Lynn Wilson ◽  
Robert Ergun ◽  
Stuart Bale ◽  
John Bonnell ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cyclotron Frequency ◽  
Plasma Waves ◽  
Electron Cyclotron ◽  
Occurrence Rate ◽  
High Time Resolution ◽  
Magnetic Field Direction ◽  
Field Orientation ◽  
Electron Cyclotron Frequency

<p>Recent studies of the solar wind sunward of 0.25 AU using the Parker Solar Probe spacecraft reveal that that solar wind can be bimodal, alternating between near quiescent regions with low turbulent fluctuation amplitudes and Parker-like magnetic field direction and regions of highly turbulent plasma and magnetic field fluctuations associated with ‘switchbacks’ of the radial magnetic field.  </p><p>The quiescent solar wind regions are highly unstable to the formation of plasma waves near the electron cyclotron frequency (fce), possibly driven by strahl electrons, which carry the solar wind heat flux, and may provide one of the most direct particle diagnostics of the solar corona at the source of the solar wind.  These waves are most intense near ~0.7 fce and ~fce. The near-fce waves are found to become more intense and more frequent closer to the Sun, and statistical evidence indicates that their occurrence rate is related to the sunward drift of the core electron population.  </p><p>In this study, we examine high time resolution burst captures of these waves, demonstrating that each wave burst contains several distinct wave types, including electron Bernstein waves and extremely narrow band waves that are highly sensitive to the magnetic field orientation. Using properties of these waves we provide evidence to support the identification of their likely plasma wave modes and the instabilities responsible for generating these waves.  By understanding the driving instabilities responsible for these waves, we infer their ability to modify electron distribution functions in the quiescent near-Sun solar wind.  </p>

scholarly journals Radial variation of whistler-mode chorus: first results from the STAFF/DWP instrument on board the Double Star TC-1 spacecraft

2005 ◽  
Vol 23 (8) ◽  
pp. 2937-2942 ◽  
Author(s):  
O. Santolík ◽  
E. Macúšová ◽  
K. H. Yearby ◽  
N. Cornilleau-Wehrlin ◽  
H. StC. K. Alleyne
Keyword(s):  
Cyclotron Frequency ◽  
Power Spectra ◽  
Double Star ◽  
Electron Cyclotron ◽  
Radial Variation ◽  
Whistler Mode ◽  
Electron Cyclotron Frequency ◽  
The Earth ◽  
First Results ◽  
Initial Results

Abstract. We use the first measurements of the STAFF/DWP instrument on the Double Star TC-1 spacecraft to investigate whistler-mode chorus. We present initial results of a systematic study on radial variation of dawn chorus. The chorus events show an increased intensity at L parameter above 6. This is important for the possible explanation of intensifications of chorus, which were previously observed closer to the Earth at higher latitudes. Our results also indicate that the upper band of chorus at frequencies above one-half of the electron cyclotron frequency disappears for L above 8. The lower band of chorus is observed at frequencies below 0.4 of the electron cyclotron frequency up to L of 11-12. The maxima of the chorus power spectra are found at slightly lower frequencies compared to previous studies. We do not observe any distinct evolution of the position of the chorus frequency band as a function of L. More data of the TC-1 spacecraft are needed to verify these initial results and to increase the MLT coverage.

Dependence of the a-Si:H Defect Density of States on the Magnetic Field Profile of an Electron Cyclotron Resonance Microwave Plasma

1992 ◽  
Vol 258 ◽  
Author(s):  
F.S. Pool ◽  
J.M. Essick ◽  
Y.H. Shing ◽  
R.T. Mather
Keyword(s):  
Magnetic Field ◽  
Density Of States ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Defect Density ◽  
Electron Cyclotron ◽  
Field Profile ◽  
Magnetic Field Profile ◽  
The Magnetic Field

ABSTRACTThe magnetic field profile of an electron cyclotron resonance (ECR) microwave plasma was systematically altered to determine subsequent effects on a-Si:H film quality. Films of a-Si:H were deposited at pressures of 0.7 mTorr and 5 mTorr with a H2/SiH4 ratio of approximately three. The mobility gap density of states ND, deposition rate and light to dark conductivity were determined for the a-Si:H films. This data was correlated to the magnetic field profile of the plasma, which was characterized by Langmuir probe measurements of the ion current density. By variation of the magnetic field profile ND could be altered by more than an order of magnitude, from 1×1016 to 1×1017 at 0.7 mTorr and 1×1016 to 5×1017 at 5 mTorr. Two deposition regimes were found to occur for the conditions of this study. Highly divergent magnetic fields resulted in poor quality a-Si:H, while for magnetic field profiles defining a more highly confined plasma, the a-Si:H was of device quality and relatively independent of the magnetic field configuration.

Electromagnetic cyclotron-loss-cone instability associated with weakly relativistic electrons

1982 ◽  
Vol 28 (3) ◽  
pp. 503-525 ◽  
Author(s):  
H. K. Wong ◽  
C. S. Wu ◽  
F. J. Ke ◽  
R. S. Schneider ◽  
L. F. Ziebell
Keyword(s):  
Cyclotron Frequency ◽  
Maximum Growth ◽  
Basic Mechanism ◽  
Electron Cyclotron ◽  
Relativistic Electrons ◽  
Electron Component ◽  
Loss Cone ◽  
Electron Cyclotron Frequency ◽  
Cone Type ◽  
Consistent Manner

The amplification of fast extraordinary mode waves with frequencies very close to the electron cyclotron frequency is investigated for a plasma which consists of a weakly relativistic electron component with a loss-cone type distribution and a cold background electron component. The basic mechanism of the amplification is attributed to a relativistic cyclotron resonance between the wave and the energetic electrons. The method employed in the present analysis enables us to solve the dispersion relation in a self-consistent manner for arbitrary ratio of the densities of the energetic and background electrons. It is found that the maximum growth rates occur at certain values of ω2pe/Ω2e and the angular dependence of the growth rate is sensitive to the ratios ω2pe/Ω2e and ne/nb. Here ωpe and Ωe are the electron plasma frequency and the electron cyclotron frequency, respectively, and ne and nb denote the number densities of the energetic and background electrons, respectively.

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