Showing papers on "Synchrotron radiation published in 1968"
Book•
01 Jan 1968
TL;DR: In this article, a book on radiation belt and magnetosphere covering Van Allen belt, Jovian synchrotron radiation, particle trapping, etc is presented, which is based on the same authors' work.
Abstract: Book on radiation belt and magnetosphere covering Van Allen belt, Jovian synchrotron radiation, particle trapping, etc
178 citations
TL;DR: In this article, it was shown that for a single electron the emission is effectively confined to within a small angular distance O(ξ) of u, where ξ = √ (1 −β 2) ≪ 1 and that the fourth Stokes parameter is to this approximation an odd function of the angle between n and u at its closest approach, and the number of electrons passing within equal angular distances ψ = ±O(λ) are equal.
Abstract: Although the synchrotron emission from a single electron moving with an ultrarelativistic velocity βc in a magnetic field B 0 is elliptically polarized, the characteristics of the polarization ellipse being determined by the position of the direction of observation n relative to the cone swept out by the direction u of the velocity vector about the direction of B 0, the resultant emission from a distribution of such gyrating electrons is, to a first approximation, linearly polarized in the direction perpendicular to the projection of B 0 on to the plane transverse to n. The reasons for this are that for a single electron the emission is effectively confined to within a small angular distance O(ξ) of u, where ξ = √ (1 −β 2) ≪ 1 and that (i) the fourth Stokes parameter is to this approximation an odd function of the angle ip between n and u at its closest approach, and (ii) the number of electrons passing within equal angular distances ψ = ±O(ξ) are equal. It follows that if ξ is large enough it is possible for the next approximation to the fourth Stokes parameter for a distribution of electrons to be significant, so that the resultant emission is elliptically polarized.
146 citations
TL;DR: Absorption measurements on copper, silver, tin, gold, and bismuth in the spectral range 50-340 A were performed using the synchrotron radiation of the 6-GeV electrons of the DESY to give rough agreement with the theoretically expected values.
Abstract: Absorption measurements on copper, silver, tin, gold, and bismuth in the spectral range 50–340 A were performed using the synchrotron radiation of the 6-GeV electron synchrotron DESY. The results are compared with previous measurements and theoretical predictions. A calculation of the partial oscillator sums from the available data gives rough agreement with the theoretically expected values.
63 citations
TL;DR: Synchrotron and X ray emission generation from upper chromosphere electrons during solar flares was studied in this article, where the authors proposed a method for generating synchrotrons and X rays from upper-chromosphere electrons.
Abstract: Synchrotron and X ray emission generation from upper chromosphere electrons during solar flares
49 citations
TL;DR: In this article, the role of quantum and spin effects on the COMPTON radiation was analyzed and it was shown that the present problem has deep analogies with the problem of the synchrotron radiation.
Abstract: The radiation of a charge moving in the field of a plane circularly polarized electromagnetic wave is discussed by the methods of classical and quantum theory both for a zeropin particle (boson) and for an electron. Such considerations allow us to analyse the role of quantum and spin effects on the radiation. It is shown that the present problem has deep analogies with the problem of the synchrotron radiation. From this point of view many physical features of COMPTON radiation are represented as simple consequences of the classical or quantum theory of synchrotron radiation.
37 citations
TL;DR: In this article, elementary analysis of radiation of a charge moving along a helix is presented. But it is not shown that the acceleration of the charge is independent of the position of the magnetic field.
Abstract: CONTENTS I. Elementary Analysis of Radiation of a Charge Moving Along a Helix 34 II. Cerenkov Radiation of a Particle Passing Through a Plate (Layer of Matter) 36 III. Synchrotron Radiation of an Individual Particle Moving at an Arbitrary Angle to the Field 37 IV. Radiation of a System of Particles 38 V. Reabsorption of Radiation of Ultrarelativistic Particles 40 VI. Magnetic-field Variation Connected with Synchrotron Radiation (Losses) Cited Literature 43
37 citations
TL;DR: The polarization of extreme uv light provided by a normal incidence monochromator used with synchrotron radiation from the 6-GeV electron synch rotatedron DESY has been measured and is in excellent agreement with the calculated polarization of the light incident upon the monochromaator grating.
Abstract: The polarization of extreme uv light provided by a normal incidence monochromator used with synchrotron radiation from the 6-GeV electron synchrotron DESY has been measured. The measured polarization increases from 82% at 500 A to 87% at 1000 A, and is in excellent agreement with the calculated polarization of the light incident upon the monochromator grating. A reflecting polarimeter consisting of a polarizer and an analyzer each made of four gold mirrors has been used in the measurement.
33 citations
TL;DR: In this article, the suppression of synchrotron emission at low frequencies, owing to the influence of the ionized medium, is investigated, and explicit expressions and detailed numerical values of the emission spectra are presented for various electron energies and plasma and cyclotron frequencies.
Abstract: The suppression of synchrotron emission at low frequencies, owing to the influence of the ionized medium, is investigated. Explicit expressions and detailed numerical values of the emission spectra are presented for various electron energies and plasma and cyclotron frequencies. Unlike previous studies of this suppression effect, which were applicable only to ultrarelativistic electrons, the present treatment is valid for electrons of arbitrary energies and in particular for intermediate energy electrons such as those presumably accelerated in solar flares.
29 citations
TL;DR: In this paper, the absorption spectra of alkali chlorides were obtained at 80°K with a 2 m grazing incidence spectrograph and interpreted in terms of X-ray exciton, electronic band structure, and two electron excitation.
27 citations
20 citations
TL;DR: In this article, the photocurrent from thin Al cathodes in a windowless electron multiplier as a function of wavelength, polarization, angle of incidence, and film thickness have been carried out in the extreme vacuum ultraviolet.
Abstract: Measurements of the photocurrent from thin Al cathodes in a windowless electron multiplier as a function of wavelength, polarization, angle of incidence, and film thickness have been carried out in the extreme vacuum ultraviolet. A normal incidence monochromator utilizing synchrotron radiation provided highly polarized light. A marked difference is found between the photocurrent measured during irradiation of thin films with “s” and “p” polarized light at wavelengths near the Al plasma wavelength (835 A). For films thicker than about 500 A pronounced interference effects are found in both “p” and “s” light at wavelengths less than the plasma wavelength. The observations can be explained by assuming the photocurrent is related to the photon density (electromagnetic energy density) in the photocathode. Calculations of the energy density in films irradiated with light give the structure found in the measured photocurrent. The measurements indicate our monochromator yields light with a degree of polarization consistent with the calculated polarization of the synchrotron radiation incident upon our grating (about 85%).
TL;DR: In this paper, the growth rate of synchrotron radiation at wave normal angle θ = 90° was derived by means of the classical kinetic approach, and it was shown that the result is identical with that obtained from the quantum treatment.
Abstract: 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.
TL;DR: Many of the observed properties of Jupiter's decametric radiation may be explained by postulation that the inner Galilean satellites of Jupiter have magnetic properties that strongly distort Jupiter's magnetic field in the region of each satellite.
Abstract: Many of the observed properties of Jupiter's decametric radiation may be explained by postulation that the inner Galilean satellites of Jupiter have magnetic properties that strongly distort Jupiter's magnetic field in the region of each satellite Charged particles from Jupiter's radiation belts are trapped by these distorted fields and emit synchrotron radiation
TL;DR: The photoionization cross-sections of platinum and tantalum, determined experimentally using the Frascati synchrotron radiation in the region of soft X-rays, are compared with the values calculated using a free atom model with central potential as discussed by the authors.
TL;DR: In this article, the authors measured the photocurrent of thin Al cathodes in a windowless electron multiplier as a function of wavelength, polarization, angle of incidence, and film thickness.
Abstract: Measurements of the photocurrent from thin Al cathodes in a windowless electron multiplier as a function of wavelength, polarization, angle of incidence, and film thickness have been carried out in the extreme vacuum ultraviolet. A normal incidence monochromator utilizing synchrotron radiation provided highly polarized light. A marked difference is found between the photocurrent measured during irradiation of thin films with “s” and “p” polarized light at wavelengths near the Al plasma wavelength (835 Å). For films thicker than about 500 Å pronounced interference effects are found in both “p” and “s” light at wavelengths less than the plasma wavelength. The observations can be explained by assuming the photocurrent is related to the photon density (electromagnetic energy density) in the photocathode. Calculations of the energy density in films irradiated with light give the structure found in the measured photocurrent. The measurements indicate our monochromator yields light with a degree of polarization consistent with the calculated polarization of the synchrotron radiation incident upon our grating (about 85%).
TL;DR: High energy electrons and emission of galactic, omnidirectional synchrotron radiation in radio frequency and X rays regions were studied in this article, showing that high energy electrons can be converted to high energy X-rays.
Abstract: High energy electrons and emission of galactic, omnidirectional synchrotron radiation in radio frequency and X rays regions
TL;DR: The reflectance of thin Al fims has been measured near the plasma wavelength (840 A) at a pressure of 2 × 10−9 Torr using synchrotron radiation as light source as mentioned in this paper.
TL;DR: In this paper, the synchrotron radiation emitted parallel and perpendicular to the magnetic axis of a hot electron plasma (Te = 80 keV) confined in a 50kG magnetic mirror field has been measured in the 4−0.2mm wavelength region of the electromagnetic spectrum by means of a spectrometer system capable of determining the absolute intensity of synchoretron radiation.
Abstract: The synchrotron radiation emitted parallel and perpendicular to the magnetic axis of a “hot electron” plasma (Te = 80 keV) confined in a 50‐kG magnetic mirror field has been measured in the 4−0.2mm wavelength region of the electromagnetic spectrum by means of a spectrometer system capable of determining the absolute intensity of the synchrotron radiation. The experimental spectrum agrees with the theoretical spectrum based on single‐particle emission and a two‐dimensional Maxwellian distribution for the plasma electrons. The electron temperature and density predicted by the measured spectrum agrees with other methods of measurement of these quantities.
TL;DR: At a wavelength of 6 cm the degree of linear polarization of the radiation from Jupiter is 0·076±0·002 as mentioned in this paper, which is consistent with the increased period of rotation determined by Komesaroff and McCulloch (1967).
Abstract: At a wavelength of 6 cm the degree of linear polarization of the radiation from Jupiter is 0·076±0·002. The variation of the direction of polarization with longitude of the central meridian is consistent with the increased period of rotation determined by Komesaroff and McCulloch (1967). There is evidence of an asymmetricl beaming of the nonthermal radiation with longitude in addition to the latitude asymmetry that was detected previously by Roberts and Komesaroff (1965). The mean flux density normalized to a distance of 4·04 a.u. is 1O·7±0·2 f.u. The small nonthermal contribution (3'7 f.u.) is further evidence for a high frequency cutoff in the synchrotron radiation; the thermal component corresponds to a brightness temperature of about 250oK.
TL;DR: In this paper, it was shown that energy in the form of magnetic field can be converted with essentially 100% efficiency into synchrotron radiation and cosmic rays under conditions expected to be present in astrophysical objects such as the Crab Nebula.
Abstract: It is shown that energy in the form of magnetic field can be converted with essentially 100% efficiency into synchrotron radiation and cosmic rays under conditions expected to be present in astrophysical objects such as the Crab Nebula. The radiation reaction from synchrotron radiation provides an effective resistance that allows merging of magnetic field lines. The induction electric field generated by this merging accelerates the electrons to restore the energy lost as radiation. In astrophysical applications this mechanism can maintain the relativistic electron energies.
TL;DR: In this article, the possibility of exciting synchrotron radiation in a system of highly relativistic monoenergetic electrons rotating in a cold collisionless magnetoactive plasma is discussed.
Abstract: In this investigation, the possibility of exciting synchrotron radiation in a system of highly relativistic monoenergetic electrons rotating in a cold collisionless magnetoactive plasma is discussed. For such a system of relativistic rotating electrons and background plasma, the temporal growth rate for synchrotron radiation is derived for general direction of observation. Evaluation of the growth rate is carried out for some parameters of interest. The spatial amplification rate of the wave is also deduced.
TL;DR: In this article, it was shown that the X-ray and the centimetric bursts are best correlated for the first events in a flare; for subsequent events they are not well correlated.
Abstract: RECENT rocket and satellite observations of 10–100 keV X-ray emission, together with ground-based observations of cm wavelength bursts, have thrown much light on the electromagnetic emission of solar flares. It is widely believed that cm wavelength emission from flares is through synchrotron radiation, while the X-ray emission is from bremsstrahlung. The correlation between the two regions of the electromagnetic spectrum has been studied in detail by Arnoldy et al.1. It has been shown that the X-ray and the centimetric bursts are best correlated for the first events in a flare; for subsequent events they are not well correlated. This type of correlation between the two phenomena can be understood if both emissions are assumed to come from a common source. This leads to various difficulties. The alternative is that the radio and the X-ray emission come through the same energetic electrons from different layers of the solar atmosphere. But, considering the various mechanisms proposed so far to explain the emissions, the problem of correlating the two remains unresolved. We therefore propose alternative mechanisms to explain this correlation.
TL;DR: In this paper, it was shown that the synchrotron intensity changes largely, if one cavity is distuned for + 50 kHz from the resonance value, when the energy of the electrons is above 630 MeV.
TL;DR: In this article, the observed electron spectrum, which is a combination of the latest results of the Minnesota group, Chicago group, Bombay group, and Leiden group, can be well expressed by a single power law (WE-2.9) for 3 50 GeV.
Abstract: When the source spectrum of cosmic-ray electrons has the form El, the equilibrium spectrum is expected to approach El-' above a critical energy E,, where E, is a function of the storage time and the energy loss rate due to synchrotron radiation and the inverse Compton effect. The observed electron spectrum, which is a combination of the latest results of the Minnesota group, Chicago group, Bombay group, and Leiden group, can be well expressed by a single power law (WE-2.9 for 3 50 GeV. These two cases lead to largely different models with respect to the source spectrum, the acceleration, the storage time, and the distribution of cosmic-ray electrons in the galaxy. The radio observations are compatible with the hypothesis based on E, < 2 GeV. Cosmic-ray electrons in the galaxy undergo various electromagnetic interactions. While they propagate through interstellar space, the original source spectruin p(E) is modified. The spectruin in the equilibriuin state J(E) is obtained as the solution of the equation
TL;DR: The individual processes of synchrotron radiation and inverse Compton scattering produce quite different photon spectra for electrons of a given energy as mentioned in this paper, however, an inverse power-law spectrum of el...
Abstract: The individual processes of synchrotron radiation and inverse Compton scattering produce quite different photon spectra for electrons of a given energy. However, an inverse power-law spectrum of el...