On the instability of synchrotron radiation

1968 ◽  
Vol 46 (9) ◽  
pp. 1073-1081 ◽  
Author(s):  
P. C. W. Fung
Keyword(s):  
Growth Rate ◽  
Synchrotron Radiation ◽  
Magnetoactive Plasma ◽  
Kinetic Approach ◽  
Relativistic Electrons ◽  
Wave Normal ◽  
Quantum Treatment ◽  
Normal Angle

In a system of isotropic relativistic electrons which is embedded in a cold ambient magnetoactive plasma, the growth rate of synchrotron radiation at wave normal angle θ = 90° is derived by means of the classical kinetic approach. It is shown that the result is identical with that obtained from the quantum treatment. Two errors occurring in the literature of synchrotron radiation are pointed out. The growth rate is computed for the case of monoenergetic electrons as an example.

Interaction of a highly relativistic helical electron stream and a cold magnetoactive plasma

1969 ◽  
Vol 47 (2) ◽  
pp. 161-177 ◽  
Author(s):  
P. C. W. Fung
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Static Magnetic Field ◽  
Pitch Angle ◽  
Magnetoactive Plasma ◽  
Electron Stream ◽  
Amplification Rate ◽  
Wave Normal ◽  
Normal Angle ◽  
Temporal Growth Rate

When a nearly monoenergetic relativistic electron stream is gyrating along a cold magnetoactive plasma with general pitch angle Φ (defined as the angle between the static magnetic field of the plasma and the momentum of a particle in the stream), the system is shown to be radiatively unstable with respect to synchrotron radiation. Using the classical kinetic approach, the temporal growth rate is derived for general wave-normal angle θ (defined as the angle between the static magnetic field and wave vector k). Deducing the spatial amplification rate from the temporal growth rate, the result obtained here is shown to be identical with that obtained from the Einstein-coefficients approach deduced by Fung earlier.

scholarly journals Excitation Of Cyclotron Electromagnetic Waves In A Magnetoactive Plasma By A Stream Of Charged Particles, Including Temperature Effects In The Stream

1966 ◽  
Vol 19 (4) ◽  
pp. 489 ◽  
Keyword(s):  
Magnetic Field ◽  
Growth Rate ◽  
Charged Particle ◽  
Temperature Effects ◽  
Electromagnetic Waves ◽  
Charged Particles ◽  
Magnetoactive Plasma ◽  
Particle Stream ◽  
Wave Normal ◽  
Normal Angle

The dispersion equation for cyclotron electromagnetic waves in a system comprising a charged particle stream injected at an angle to the static magnetic field of a magnetoactive plasma is derived for a general wave�normal angle () when the temperature of the stream has been taken into account. The expression for the growth rate is derived in general for all cyclotron waves.

Synchrotron radiation from single electrons gyrating in a magnetoactive plasma

1969 ◽  
Vol 47 (7) ◽  
pp. 757-768 ◽  
Author(s):  
P. C. W. Fung
Keyword(s):  
Synchrotron Radiation ◽  
Plasma Frequency ◽  
Radiation Power ◽  
Magnetoactive Plasma ◽  
Electron Plasma ◽  
Relativistic Electrons ◽  
Relative Importance ◽  
Numerical Examples ◽  
The Past ◽  
Single Electrons

In this paper, the incoherent synchrotron radiation power emitted by relativistic electrons gyrating in a cold magnetoactive plasma is rederived, correcting errors which have occurred in the past literature. One can specify the background plasma by the quantity A = ωp2/ωH2 (ωp is the angular electron plasma frequency and ωH is the angular electron gyro-frequency), i.e. the relative importance of the plasma frequency to the gyro-frequency. The general spectral features of synchrotron radiation from single electrons radiating in plasmas of large [Formula: see text] and small [Formula: see text] are discussed with the aid of a number of numerical examples.

scholarly journals Microstructure Evolution of Ag/TiO2 Thin Film

2021 ◽  
Vol 7 (1) ◽  
pp. 14
Author(s):  
Dewi Suriyani Che Halin ◽  
Kamrosni Abdul Razak ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Mohd Izrul Izwan Ramli ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Growth Rate ◽  
Synchrotron Radiation ◽  
Tio2 Thin Film ◽  
Sol Gel ◽  
Tio2 Thin Films ◽  
Contact Mode ◽  
X Ray ◽  
Radiation Imaging

Ag/TiO2 thin films were prepared using the sol-gel spin coating method. The microstructural growth behaviors of the prepared Ag/TiO2 thin films were elucidated using real-time synchrotron radiation imaging, its structure was determined using grazing incidence X-ray diffraction (GIXRD), its morphology was imaged using the field emission scanning electron microscopy (FESEM), and its surface topography was examined using the atomic force microscope (AFM) in contact mode. The cubical shape was detected and identified as Ag, while the anatase, TiO2 thin film resembled a porous ring-like structure. It was found that each ring that coalesced and formed channels occurred at a low annealing temperature of 280 °C. The energy dispersive X-ray (EDX) result revealed a small amount of Ag presence in the Ag/TiO2 thin films. From the in-situ synchrotron radiation imaging, it was observed that as the annealing time increased, the growth of Ag/TiO2 also increased in terms of area and the number of junctions. The growth rate of Ag/TiO2 at 600 s was 47.26 µm2/s, and after 1200 s it decreased to 11.50 µm2/s and 11.55 µm2/s at 1800 s. Prolonged annealing will further decrease the growth rate to 5.94 µm2/s, 4.12 µm2/s and 4.86 µm2/s at 2400 s, 3000 s and 3600 s, respectively.

A Gyro-Synchrotron Maser in the Solar Corona?

1978 ◽  
Vol 3 (3) ◽  
pp. 231-233 ◽  
Author(s):  
D. B. Melrose ◽  
S. M. White
Keyword(s):  
Synchrotron Radiation ◽  
Solar Corona ◽  
Brightness Temperature ◽  
Early Phase ◽  
Relativistic Electrons ◽  
High Brightness ◽  
Brightness Temperatures ◽  
Type Iv ◽  
Alternative Suggestion ◽  
Lower Frequencies

Stewart (1978) has reported four moving type IV bursts observed with the Culgoora radio heliograph at 43, 80 and 160 MHz. After an early phase, the brightness temperatures of the observed bursts decreased with increasing frequency and with time. The highest brightness temperature observed at 43 MHz was 1010K, and it seems that the brightness temperature would have been still higher at even lower frequencies. Existing theoretical ideas on moving type IV bursts are based on data (at 80 MHz primarily) which included no brightness temperatures in excess of 109K. the accepted interpretation involved gyro-synchrotron radiation from mildly relativistic electrons (energies ≈ 100 keV); reabsorption by the electrons themselves restricts the brightness temperature to less than about 100 keV ≈ 109K (Wild and Smerd 1972, Dulk 1973). Stewart’s (1978) new data at 43 MHz require that this accepted interpretation be modified; he has suggested that higher energy electrons are involved. An alternative suggestion is explored here, namely that the absorption might be negative. In other words, the high brightness temperatures observed could be due to a gyro-synchrotron maser involving electrons with energies of about 100 keV.

scholarly journals Sensitivity of EMIC Wave‐Driven Scattering Loss of Ring Current Protons to Wave Normal Angle Distribution

2019 ◽  
Vol 46 (2) ◽  
pp. 590-598 ◽  
Author(s):  
Xing Cao ◽  
Binbin Ni ◽  
Danny Summers ◽  
Yuri Y. Shprits ◽  
Xudong Gu ◽  
...  
Keyword(s):  
Ring Current ◽  
Angle Distribution ◽  
Scattering Loss ◽  
Emic Wave ◽  
Wave Normal ◽  
Normal Angle

Oblique whistler-mode propagation in a hot anisotropic plasma

1982 ◽  
Vol 27 (2) ◽  
pp. 199-204 ◽  
Author(s):  
S. S. Sazhin ◽  
E. M. Sazhina
Keyword(s):  
Magnetic Field ◽  
Dispersion Relation ◽  
Plasma Temperature ◽  
Anisotropic Plasma ◽  
Mode Propagation ◽  
Whistler Mode ◽  
Energy Focusing ◽  
Wave Normal ◽  
The Magnetic Field ◽  
Normal Angle

An approximate dispersion relation is obtained for quasi-longitudinal whistler mode propagation in the hot anisotropic plasma. The influence of plasma temperature and anisotropy on whistler energy focusing along the magnetic field and whistler trapping in the magnetospheric ducts are considered for the case when the whistler wave normal angle is not equal to zero.

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