Low-altitude ISIS 1 observations of auroral radio emissions and their significance to the cyclotron maser instability

1987 ◽  
Vol 92 (A2) ◽  
pp. 1218 ◽  
Author(s):  
Robert F. Benson ◽  
H. K. Wong
Keyword(s):  
Radio Emissions ◽  
Cyclotron Maser ◽  
Low Altitude

scholarly journals Numerical simulations of unbounded cyclotron-maser emissions

2013 ◽  
Vol 79 (6) ◽  
pp. 999-1001 ◽  
Author(s):  
DAVID C. SPEIRS ◽  
S. L. McCONVILLE ◽  
K. M. GILLESPIE ◽  
A. D. R. PHELPS ◽  
K. RONALD
Keyword(s):  
Radio Emission ◽  
Numerical Simulations ◽  
Source Region ◽  
Radio Emissions ◽  
Cyclotron Maser ◽  
Thermal Radio ◽  
Thermal Radio Emission ◽  
Electron Cyclotron Masers ◽  
Coupling Characteristics ◽  
Significant Bearing

AbstractNumerical simulations have been conducted to study the spatial growth rate and emission topology of the cyclotron-maser instability responsible for stellar/planetary auroral magnetospheric radio emission and intense non-thermal radio emission in other astrophysical contexts. These simulations were carried out in an unconstrained geometry, so that the conditions existing within the source region of some natural electron cyclotron masers could be more closely modelled. The results have significant bearing on the radiation propagation and coupling characteristics within the source region of such non-thermal radio emissions.

scholarly journals A model of so-called "Zebra" emissions in solar flare radio burst continua

2011 ◽  
Vol 29 (9) ◽  
pp. 1673-1682 ◽  
Author(s):  
R. A. Treumann ◽  
R. Nakamura ◽  
W. Baumjohann
Keyword(s):  
Narrow Band ◽  
Radio Continuum ◽  
Radio Emissions ◽  
Zebra Pattern ◽  
Cyclotron Maser ◽  
Broadband Radio ◽  
Ion Cyclotron ◽  
Electric Potential Field ◽  
Cyclotron Harmonics ◽  
Electron Maser

Abstract. A simple mechanism for the generation of electromagnetic "Zebra" pattern emissions is proposed. "Zebra" bursts are regularly spaced narrow-band radio emissions on the otherwise broadband radio continuum emitted by the active solar corona. The mechanism is based on the generation of an ion-ring distribution in a magnetic mirror geometry in the presence of a properly directed field-aligned electric potential field. Such ion-rings or ion-conics are well known from magnetospheric observations. Under coronal conditions they may become weakly relativistic. In this case the ion-cyclotron maser generates a number of electromagnetic ion-cyclotron harmonics which modulate the electron maser emission. The mechanism is capable of switching the emission on and off or amplifying it quasi-periodically which is a main feature of the observations.

Ganymede-induced decametric emission: in-situ measurements by Juno.

2020 ◽  
Author(s):  
Corentin Louis ◽  
Philippe Louarn ◽  
William Kurth ◽  
Frederic Allegrini ◽  
Jamey Szalay
Keyword(s):  
Flux Tube ◽  
In Situ Measurements ◽  
Magnetic Flux Tube ◽  
Electron Population ◽  
Radio Emissions ◽  
Cyclotron Maser ◽  
Galilean Moons ◽  
Field Lines ◽  
The Magnetic Field

<p><em class=""><span class="">At Jupiter, part of the auroral radio emissions are controlled by the Galilean moons Io,</span><span class=""> </span><span class="">Europa and Ganymede. Until now, they have been remotely detected using ground-based </span><span class="">radio-telescope or electric antenna aboard spacecraft. The polar trajectory of the Juno</span><span class=""> </span><span class="">orbiter leads to cross the magnetic flux tube connected to these moons, or their tail, and </span><span class="">gives a direct in-situ measurements of the characteristics </span><span class="">of these decametric moon induced radio emissions </span><span class="">(such as the electron population, size of the source, and beaming</span><span class=""> </span><span class="">angle and growth rate of the emission)</span><span class="">. In this study,</span><span class=""> </span><span class="">we focus on the crossing of the Ganymede flux tube. The study of Juno/JADE-E and</span><span class=""> </span><span class="">Juno/Waves data leads to an estimated source size of a few 100s km,</span><span class=""> an electron population of energy </span><span class="">E</span><span class="">= 8</span><span class="">±</span><span class="">2 keV and an emission beaming angle</span><span class=""> </span><span class="">of </span><span class="">θ</span><span class="">= 80</span><span class="">±</span><span class="">2</span><span class="">° </span><span class="">from the magnetic field lines. Finally, this crossing of a decametric radio emission induced by a moon brings us new constrains on the Cyclotron Maser Instability process</span></em></p>

Lower ionospheric cyclotron maser theory: A possible source of 2ƒceand 3ƒceauroral radio emissions

1996 ◽  
Vol 101 (A12) ◽  
pp. 27015-27025 ◽  
Author(s):  
Peter H. Yoon ◽  
A. T. Weatherwax ◽  
T. J. Rosenberg ◽  
J. LaBelle
Keyword(s):  
Radio Emissions ◽  
Cyclotron Maser

scholarly journals Juno reveals new insights into Io-related decameter radio emissions

2020 ◽  
Author(s):  
Yasmina M Martos ◽  
Masafumi Imai ◽  
John E.P. Connerney ◽  
Stavros Kotsiaros ◽  
William S. Kurth
Keyword(s):  
Magnetic Field ◽  
Field Model ◽  
Loss Cone ◽  
Radio Emissions ◽  
Cyclotron Maser ◽  
Magnetic Field Model ◽  
Decameter Radio ◽  
Resonant Electron ◽  
Field Geometry ◽  
Improved Accuracy

<p>The Juno spacecraft has been orbiting Jupiter since July 2016 providing stunning new information about the planet and its environment. The new magnetic field model, JRM09, with much improved accuracy near the planet, provides the basis for a better understanding of Io-related decametric radio emissions and implications for auroral processes. Here, we study Io-related DAM events observed by the Juno Waves instrument to estimate the beaming angle, the resonant electron energy and radio source location by forward modeling. The JRM09 magnetic field model is used to better constrain the location and observability of the radio emissions, and characterize the loss cone-driven electron cyclotron maser instability. We obtained good agreement between synthetic and observed arcs. The estimated beaming cone half-angles range from 33° to 85° and the obtained resonant electron energies are up to 23 times higher than previously proposed. Additionally, we quantitatively analyze the higher likelihood of observing groups of arcs originating in the northern hemisphere relative to those originating in the southern hemisphere. This is primarily a consequence of the asymmetry of the magnetic field geometry, observer location, and pitch angles of the electrons at the equator.  </p>

scholarly journals The low-frequency source of Saturn’s kilometric radiation

Science ◽  
2018 ◽  
Vol 362 (6410) ◽  
pp. eaat2027 ◽  
Author(s):  
L. Lamy ◽  
P. Zarka ◽  
B. Cecconi ◽  
R. Prangé ◽  
W. S. Kurth ◽  
...  
Keyword(s):  
Source Region ◽  
Low Frequency ◽  
Auroral Oval ◽  
Emission Region ◽  
Radio Emissions ◽  
Cyclotron Maser ◽  
Frequency Source ◽  
Field Lines ◽  
Plasma Measurements

Understanding how auroral radio emissions are produced by magnetized bodies requires in situ measurements within their source region. Saturn’s kilometric radiation (SKR) has been widely used as a remote proxy of Saturn’s magnetosphere. We present wave and plasma measurements from the Cassini spacecraft during its ring-grazing high-inclination orbits, which passed three times through the high-altitude SKR emission region. Northern dawn-side, narrow-banded radio sources were encountered at frequencies of 10 to 20 kilohertz, within regions of upward currents mapping to the ultraviolet auroral oval. The kilometric waves were produced on the extraordinary mode by the cyclotron maser instability from 6– to 12–kilo–electron volt electron beams and radiated quasi-perpendicularly to the auroral magnetic field lines. The SKR low-frequency sources appear to be strongly controlled by time-variable magnetospheric electron densities.

scholarly journals Long-duration Coherent Radio Emission from the dMe Star Proxima Centauri

2003 ◽  
Vol 20 (3) ◽  
pp. 257-262 ◽  
Author(s):  
O. B. Slee ◽  
A. J. Willes ◽  
R. D. Robinson
Keyword(s):  
Radio Emission ◽  
Flare Star ◽  
Short Term ◽  
Radio Emissions ◽  
Cyclotron Maser ◽  
Long Duration ◽  
Responsible Mechanism ◽  
Narrow Bandwidth ◽  
Solar Radio Emissions ◽  
Receiver Bandwidth

AbstractThe Australia Telescope and Anglo-Australian Telescope were used in May 2000 to record the radio and optical emissions from the dMe flare star Proxima Centauri. Eight bright optical flares over a two-day interval resulted in no detectable excess short-term radio emission at 1.38 and 2.50 GHz. However, a slowly declining 1.38 GHz emission over the two-day interval was nearly 100% right circular polarised and was restricted to a relatively narrow bandwidth with total intensity (I) and circular polarisation (V) varying significantly over the 104 MHz receiver bandwidth. These are the first observations to show that highly-polarised narrowband flare star emission can persist for several days. This signature is attributed to sources of coherent radio emission in the star's corona. Similarities with various solar radio emissions are discussed; however, it is not possible with the existing observations to distinguish between fundamental plasma emission and electron–cyclotron maser emission as the responsible mechanism.

scholarly journals The Loss-cone Driven Electron-cyclotron Maser

1982 ◽  
Vol 35 (4) ◽  
pp. 447 ◽  
Author(s):  
RG Hewitt ◽  
DB Melrose ◽  
KG Rönnmark
Keyword(s):  
Relativistic Correction ◽  
Electron Cyclotron ◽  
Important Class ◽  
Instability Mechanism ◽  
Loss Cone ◽  
Radio Emissions ◽  
Electron Cyclotron Maser ◽  
Cyclotron Maser ◽  
Class B

Electron-cyclotron instabilities may be classified in two ways depending on whether the relativistic correction to the gyrofrequency is important (class S) or not (class N), and whether the instability mechanism is of a maser type (class M) or due to bunching (class B). Renewed interest in class SM has followed the Wu and Lee application of it to the interpretation of terrestrial kilometric radiation. The maser is assumed to be driven by a one-sided loss-cone distribution of electrons. This mechanism seems particularly favourable for the interpretation of certain planetary, solar and stellar radio emissions

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