Jupiter and Saturn

1974 ◽  
Vol 336 (1604) ◽  
pp. 63-84 ◽  
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Charged Particles ◽  
Internal Heat ◽  
Atmospheric Temperature ◽  
Radio Spectrum ◽  
Radiation Belts ◽  
Theoretical Interpretation ◽  
Gravitational Fields ◽  
Wide Range

Jupiter, the largest planet, and Saturn, the second largest, contain nine-tenths of the material of the solar system outside the Sun and most of the angular momentum of the solar system is associated with their orbital motion. Both planets rotate very rapidly (rotation periods ~ 10 h) and possess rich satellite systems. Owing to their strong gravitational fields and low surface temperatures, Jupiter and Saturn may, unlike the ‘terrestrial’ planets, be fairly close in chemical composition to the primordial material out of which the solar system originally formed; they consist mainly of hydrogen, much of which is compressed to a metallic form. Jupiter is the only planet other than Earth showing evidence of a general magnetic field. Absorption of incident solar energy accounts for less than one-half the estimated total thermal (infrared) radiation emitted by Jupiter and Saturn. The balance is probably due to internal heat sources and could be accounted for in terms of a gravitational contraction at about 0.1 cm/year. The outward flow of heat should maintain the atmospheric temperature gradients close to their adiabatic values, which is a significant result for theories of atmospheric motions (see appendix A). These theories are largely concerned with explaining the rough alinement of clouds in bands parallel to the equator, the presence of strong eastward equatorial currents, the occurrence of transient spots and other irregular markings and, in the case of Jupiter, the nature of the enigmatic Great Red Spot. Jupiter, unlike Saturn, is a strong emitter of non-thermal radio noise on decametre and decimetre wavelengths. Plausible theories of this radio emission invoke a strong Jovian dipole magnetic field and an associated system of van Allen-type ‘radiation’ belts of electrically-charged particles extending beyond and interacting with the first Galilean satellite Io. The most likely source of the Jovian magnetic field - which theories of Jupiter’s internal constitution must now take properly into account - is a hydromagnetic dynamo (see appendix B) associated with fluid motions in the electrically-conducting parts of Jupiter’s interior. The absence of a non-thermal component in Saturn’s radio spectrum implies that radiation belts cannot form around that planet, possibly because Saturn is non-magnetic or, if it is magnetic, because charged particles in the vicinity of Saturn are rapidly removed through interactions with Saturn’s rings. Modern research on Jupiter and Saturn is based on a rich variety of data, soon to be augmented by observations from space-craft. Future progress with the theoretical interpretation of these data in terms of improved models of the structure and evolution of the giant planets will involve not only the further application of a wide range of established knowledge but also the development of new ideas in several areas of basic science. The paper ends with two appendices, on the dynamics of rapidly rotating non-homogeneous fluids and on hydromagnetic dynamos.

scholarly journals EVIDENCE OF THE EARTH’S INNER RADIATION BELTS DURING THE LOW SOLAR AND GEOMAGNETIC ACTIVITY OBTAINED WITH THE STEP-F INSTRUMENT

2021 ◽  
Vol 26 (3) ◽  
pp. 224-238
Author(s):  
O. V. Dudnik ◽  
◽  
O. V. Yakovlev ◽  
Keyword(s):  
Geomagnetic Activity ◽  
Radiation Belt ◽  
Charged Particles ◽  
Radiation Belts ◽  
Outer Radiation Belt ◽  
Earth’S Magnetosphere ◽  
High Latitude Region ◽  
Wide Range ◽  
Earth's Magnetosphere ◽  
Particle Fluxes

Purpose: The subject of research is the spatio-temporal charged particles in the Earth’s magnetosphere outside the South Atlantic magnetic Anomaly during the 11-year cycle of solar activity minimum. The work aims at searching for and clarifying the sustained and unstable new spatial zones of enhanced subrelativistic electron fluxes at the altitudes of the low Earth orbit satellites. Design/methodology/approach: Finding and ascertainment of new radiation belts of the Earth were made by using the data analysis from the D1e channel of recording the electrons of energies of ΔEe=180–510 keV and protons of energies of ΔEp=3.5–3.7 MeV of the satellite telescope of electrons and protons (STEP-F) aboard the “CORONAS-Photon” Earth low-orbit satellite. For the analysis, the data array with the 2 s time resolution normalized onto the active area of the position-sensitive silicon matrix detector and onto the solid angle of view of the detector head of the instrument was used. Findings: A sustained structure of three electron radiation belts in the Earth’s magnetosphere was found at the low solar and geomagnetic activity in May 2009. The two belts are known since the beginning of the space age as the Van Allen radiation belts, another additional permanent layer is formed around the drift shell with the McIlwaine parameter of L = 1.65±0.05. On some days in May 2009, the new two inner radiation belts were observed simultaneously, one of those latter being recorded between the investigated sustained belt at L≈1.65 and the Van Allen inner belt at L≈2.52. Increased particle fluxes in this unstable belt have been formed with the drift shell L≈2.06±0.14. Conclusions: The new found inner radiation belts are recorded in a wide range of geographic longitudes λ, both at the ascending and descending nodes of the satellite orbit, from λ1≈150° to λ2≈290°. Separately in the Northern or in the Southern hemispheres, outside the outer edge of the outer radiation belt, at L≥7–8, there are cases of enhanced particle fl ux density in wide range of L-shells. These shells correspond to the high-latitude region of quasi-trapped energetic charged particles. Increased particle fluxes have been recorded up to the bow shock wave border of the Earth’s magnetosphere (L≈10-12). Key words: radiation belt, STEP-F instrument, electrons, magnetosphere, drift L-shell, particle flux density

scholarly journals Examining the students’ understanding level towards the concepts of magnetic field: the case of conducting wire

2019 ◽  
Vol 6 (2) ◽  
pp. 40-46
Author(s):  
Ozgur Ozcan
Keyword(s):  
Magnetic Field ◽  
Charged Particles ◽  
Alternative Conceptions ◽  
Physics Teachers ◽  
Content Analysis Method ◽  
Wide Range ◽  
Conducting Wire ◽  
The University ◽  
Electrically Charged

The electromagnetism is one of the important topics in physics and it has quite a lot of applications in a wide range of area. It also examines the electromagnetic force researches that occur between the electrically charged particles. On the other hand, examination of the magnetic field around the conductors and the movement of the charged particles in the electromagnetic field is quite interesting topics on that the physics researchers intensively investigated. The electromagnetic theory has an abstract nature, because the university level students have many learning and understanding difficulties about the concepts related to these topics. In realization of meaningful learning, the role of the students’ prior knowledge about the aforementioned concepts is becoming important. This study aims to investigate the understanding of 12 pre-service physics teachers related to the concept of moving particles in an electromagnetic filed by using the qualitative research methods. The data collected through the test consisting of three question and it was analysed by using content analysis method. The understanding levels and the alternative conceptions of the pre-service physics teachers were determined by different categories at the end of the content analyses process.   Keywords: Alternative conceptions, electromagnetism education, pre-service physics teachers; understanding level;

scholarly journals Summary

1974 ◽  
Vol 3 ◽  
pp. 493-498
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Radio Emission ◽  
Rotation Axis ◽  
Radiation Belts ◽  
Main Magnetic Field ◽  
High Brightness ◽  
Brightness Temperatures ◽  
Pulsar Radiation ◽  
Wide Range

Professor G. R. A. Ellis reviewed the wide range of radio emission from Jupiter. At centimetric wavelengths the thermal radiation corresponds to a blackbody at 130K. Between 2 m and 10 cm wavelength there is a powerful component of synchrotron radiation from the electrons trapped in the radiation belts. At longer wavelengths there is a great variety of impulsive radio emission from coherent plasma oscillations.The magnetic field of Jupiter is known from the polarisation of the synchrotron radiation to be situated centrally (within one tenth of the radius) and inclined at 10° to the rotation axis. The radiating electrons have energies of the order of 10 MeV, and a density of 10”-3 cm-3, much greater than in the case of the Earth’s radiation belts.The decametric radiation varies with the rotation of Jupiter, possibly analogously to pulsar radiation. Bursts at around 4 MHz reach very high brightness temperatures, exceeding 1017 K. The occurrence of these strong bursts is closely related to the position of the Jovian satellite Io, which must have an interaction with the main magnetic field.

Aurora in Planetary Atmospheres

2020 ◽  
Author(s):  
Steve Miller
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar System ◽  
Magnetic Moment ◽  
Interplanetary Space ◽  
Magnetic Moments ◽  
Charged Particles ◽  
High Energy ◽  
Atoms And Molecules ◽  
Electrically Charged

Planetary aurorae are some of the most iconic and brilliant (in all senses of the word) indicators that not only are we all interconnected on our own planet Earth, but that we are connected throughout the entire solar system as well. They are testimony to the centrality of the Sun, not just in providing the essential sunlight that drives weather systems and makes habitability possible, but in generating a high-velocity wind of electrically charged particles—known as the solar wind—that buffets each of the planets in turn as it streams outward through interplanetary space. In some cases, those solar-wind particles actually cause the aurorae; in others, their pressure prompts and modifies what is already happening within the planetary system as a whole. Aurorae are created when electrically charged particles—predominantly negatively charged electrons or positive ions such as protons, the nuclei of hydrogen—crash into the atoms and molecules of a “planetary” atmosphere. They are guided and accelerated to high energies by magnetic field lines that tend to concentrate them toward the (magnetic) poles. Possessing energies usually measured in hundreds and thousands, all the way up to many millions, of electron Volts (eV), these energetic particles excite the atoms and molecules that constitute the atmosphere. At these energies, such particles can excite the electrons in atoms and molecules from their ground state to higher levels. The atoms and molecules that have been excited by these high-energy collisions can then relax, emitting light immediately after the collision, or after they have been “thermalized” by the surrounding atmosphere. Either way, the emitted radiation is at certain well-defined wavelengths, giving characteristic colors to the aurorae. Just how many particles, how much atmosphere, and what strength of magnetic field are required to create aurorae is an open question. Earth has a moderately sized magnetic field, with a magnetic moment measured at 7.91x1015 Tesla m3 (T m3). It has a moderate atmosphere, too, giving a standard sea-level pressure of 101,325 Pascal (Pa), or 1.01325 bar. The density of the solar wind at Earth is about 6 million per cubic meter (6x106 m-3). Earth has very bright aurorae. Mercury has a magnetic moment 0.7% of that of Earth and no atmosphere to speak of, and consequently no aurorae. But aurorae have been reported on both Venus and Mars, even though they both have surface magnetic fields much less than Mercury: they both have atmospheres, albeit Mars is very rarefied. The giant planets—Jupiter, Saturn, Uranus, and Neptune—have magnetic moments tens, hundreds, and (in the case of Jupiter) thousands of times that of Earth. They all have thick atmospheres, and all of them have aurorae (although Neptune’s has not been seen since the days of the Voyager spacecraft). The aurorae of the solar system are very varied, variable, and exciting.

FOCUSING OF CHARGED PARTICLES IN A CYLINDRICALLY SYMMETRIC MAGNETIC FIELD PROPORTIONAL TO r−1

1963 ◽  
Vol 41 (3) ◽  
pp. 496-532 ◽  
Author(s):  
G. E. Lee-Whiting
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Point Source ◽  
Charged Particles ◽  
Source Area ◽  
Cylindrically Symmetric ◽  
Finite Source ◽  
Flat Type ◽  
Wide Range ◽  
Finite Aperture

The aberrations associated with skew trajectories lying near the midplane of a "flat"-type β spectrometer with a magnetic field falling off as r−1 have been surveyed over wide ranges of values of the field strength at the source and of the angle of emission; Lafoucrière (1950) showed that such a field possesses a perfect focus for midplanar orbits. A field strength has been found for which the aberrations corresponding to finite aperture are exceedingly small; with a point source it would be possible to get transmissions of 2.3% and 6.0% at resolutions of 0.01% and 0.1% respectively. The defocusing resulting from finite source-height has been studied for this particular value of the field strength and has been found to be large; the resulting permissible source-area is so small that the luminosity of the instrument is inferior to that of a π√2 spectrometer.Methods of producing fields varying as r−1 over a wide range of r have been investigated; both iron pole-pieces and iron-free coils have been considered.

scholarly journals Magnetic Stress in Solar System Plasmas

1999 ◽  
Vol 52 (4) ◽  
pp. 733 ◽  
Author(s):  
C. T. Russell
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Current Sheet ◽  
Giant Cells ◽  
The Sun ◽  
Flux Tubes ◽  
Reconnection Region ◽  
Wide Range ◽  
Varying Environments ◽  
The Magnetic Field

Magnetic stresses play an important role in the dynamics of geophysical systems, from deep inside the Earth to the tenuous plasmas of deep space. In the magnetic dynamos inside the sun and the planets, the magnetic stresses of necessity rival the interior mechanical stresses. In solar system plasmas, magnetic stresses play critical roles in the transfer of mass, momentum and energy from one region to another. Coronal mass ejections are rapidly expelled from the sun and their interplanetary manifestations plough through the pre-existing solar wind. Some of these structures resemble flux ropes, bundles of magnetic field wrapped around a central core, and some of these appear to be almost force-free. These structures and similar ones in planetary magnetospheres appear to be created by the mechanism of magnetic reconnection. Solar system plasmas generally organise themselves in giant cells in which the properties are rather uniform, separated by thin current layers across which the properties change rapidly. When the magnetic field on the two sides of one of these current layers changes direction significantly (by over 90°), the magnetic field on opposite sides of the boundary may become linked across the current sheet. If the resulting magnetic stress can accelerate the plasma out of the reconnection region, the process will continue uninterrupted. If not, the process will shut itself off. Such continuous reconnection can occur at the Earth’s magnetopause and those of the magnetised planets. Reconnection in the terrestrial magnetotail current sheet and the jovian current sheet occurs in a setting in which the flow can be blocked on one side, causing reconnection to be inherently time-varying. At Jupiter, this mechanism also separates heavy ions from magnetospheric flux tubes so that the ions can escape but Jupiter can retain its magnetic field. Despite the very wide range of parameters and scales encountered in heliospheric plasmas, there is surprising coherence in the mechanisms in these varying environments.

scholarly journals Particle Source and Loss Processes

2021 ◽  
pp. 159-211
Author(s):  
Hannu E. J. Koskinen ◽  
Emilia K. J. Kilpua
Keyword(s):  
Magnetic Field ◽  
Cosmic Radiation ◽  
Charged Particles ◽  
Radiation Belts ◽  
Great Variability ◽  
The Sun ◽  
Outer Electron ◽  
Inner Magnetosphere ◽  
Near Earth Space ◽  
Scientific Task

AbstractThe main sources of charged particles in the Earth’s inner magnetosphere are the Sun and the Earth’s ionosphere. Furthermore, the Galactic cosmic radiation is an important source of protons in the inner radiation belt, and roughly every 13 years, when the Earth and Jupiter are connected via the interplanetary magnetic field, a small number of electrons originating from the magnetosphere of Jupiter are observed in the near-Earth space. The energies of solar wind and ionospheric plasma particles are much smaller than the particle energies in radiation belts. A major scientific task is to understand the transport and acceleration processes leading to the observed populations up to relativistic energies. Equally important is to understand the losses of the charged particles. The great variability of the outer electron belt is a manifestation of the continuously changing balance between source and loss mechanisms, whereas the inner belt is much more stable.

Monte Carlo calculation of the energy parameters and spatial distribution of the cathodic arc ions while passing through the macro-particles filters

2018 ◽  
Vol 1 (1) ◽  
pp. 30-34 ◽  
Author(s):  
Alexey Chernogor ◽  
Igor Blinkov ◽  
Alexey Volkhonskiy
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Monte Carlo ◽  
Monte Carlo Calculation ◽  
Inhomogeneous Magnetic Field ◽  
Flow Energy ◽  
Wide Range ◽  
Field Concentrator ◽  
Cathodic Arc ◽  
The Magnetic Field

The flow, energy distribution and concentrations profiles of Ti ions in cathodic arc are studied by test particle Monte Carlo simulations with considering the mass transfer through the macro-particles filters with inhomogeneous magnetic field. The loss of ions due to their deposition on filter walls was calculated as a function of electric current and number of turns in the coil. The magnetic field concentrator that arises in the bending region of the filters leads to increase the loss of the ions component of cathodic arc. The ions loss up to 80 % of their energy resulted by the paired elastic collisions which correspond to the experimental results. The ion fluxes arriving at the surface of the substrates during planetary rotating of them opposite the evaporators mounted to each other at an angle of 120° characterized by the wide range of mutual overlapping.

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