2 edition of Potential structures and particle acceleration on auroral field lines found in the catalog.
Potential structures and particle acceleration on auroral field lines
David J Gorney
|Contributions||Aerospace Corporation, United States. Air Force. Space Division|
|The Physical Object|
|Pagination||, 32 p. :|
|Number of Pages||32|
We consider the interaction of Alfven waves with the auroral acceleration region (AAR). The AAR is characterized by an electric potential drop that supports a field-aligned upward current and the acceleration of precipitating electrons. An Alfven wave incident on the AAR from the magnetosphere partially reflects back and partially penetrates into the AAR. The third particle distribution that shows evidence of local energization is that of the narrowly field-aligned electron beams (Sharp et al ; Collin et al ). These electrons are often seen flowing up and down magnetic field lines (counterstreaming). The fourth particle distribution is the ion conic (Ghielmetti.
A field-aligned potential drop was first proposed in the mids by David Evans to explain the monoenergetic electron beams observed in association with auroral arcs. 10 Evidence for the existence of such structures has been provided by double probe measurements, chemical release experiments, and particle data. The repetitive structure of a linear accelerator naturally suggests the use of alternating rather than constant voltages to create the electric fields. A positively charged particle accelerated toward a negative potential, for example, will receive a renewed push if the potential becomes positive as the particle passes by.
TDS were first observed in the magnetosphere along auroral zone magnetic field lines on the S3‐3 satellite [Mozer et al., ; Temerin et al., ] and they were more thoroughly studied on the FAST mission [Ergun et al., , ]. 3. The parallel electric field in the low altitude acceleration region is significant, sometimes as large as hundreds of mV/m. The high altitude auroral acceleration region Returning to Fig. 1, the sole assumption of the model is that the boundary condition imposed on the auroral acceleration region is an upward field-aligned current. As.
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Get this from a library. Potential structures and particle acceleration on auroral field lines. [David J Gorney; Aerospace Corporation.; United States. Air Force. Space Division.]. In the 's major advances in the understanding of auroral processes were brought about by observations of plasmas and electric fields within the regions of space responsible for auroral particle acceleration.
The major contribution of these observations was the verification of the existence of electric fields with components parallel to the magnetic field over large regions of Author: D. Gorney. The study of auroral potential structures is one of the primary objectives of the Dynamics Explorer (DE) program.
Instrumentation was specifically des Author: R.A. Hoffman. potential structures and particle acceleration on auroral field lines_____ s.
performing ono. report hnger tra() -6 7. authort.) ct on gran t hnmue_&) david j. gorney 9. performing organization name and address program element.
project. task area a. Solitons and double layers in U-shaped potential structures give rise to spiky electric fields also perpendicular to the magnetic field in agreement with satellite measurements.
The large scale potential structures associated with inverted V -events are built up of many similar short-lived structures on a small by: New model for auroral acceleration: O-shaped potential structure cooperating with waves P. Janhunen1, A. Olsson1;2 1 Finnish Meteorological Institute, Geophysical Research, P.O.
BoxFIN Helsinki, Finland e-mail: [email protected]ﬁ 2 Swedish Institute of Space Physics, Uppsala Division, Uppsala, Sweden Received: 27 May / Revised: 7 February. the auroral field line. They then investigated the evolution of the auroral acceleration region from the AKR spectral behavior and obtained information on the vertical structure of the acceleration region and its dynamic behavior prior to and during a substorm.
Dual acceleration regions at sub-storm onset were identified: a low-altitude one and. Measurements on the S and Viking satellites appear to show that at least a large fraction of magnetic field-aligned potential drops are made up of multiple double layers.
Solitons and double layers inU-shaped potential structures give rise to spiky electric fields also perpendicular to the magnetic field in agreement with satellite measurements. The role of waves in accelerating both electrons and ions in the auroral zone is discussed.
Various wave generation mechanisms and acceleration processes including acceleration within cavitons and nonlinear potential structures are analysed. The wave modes which we consider include waves such as kinetic Alfvén waves, and lower-hybrid waves.
Particle Acceleration in the Magnetotail and Aurora and the radiation belts. The general structure of the magnetosphere and its current systems are illustrated in Fig. The importance and (X-line) and for auroral acceleration by ﬁeld-aligned electric ﬁelds.
In the adiabatic limit, cross-tail curvature/gradient drift in the. The auroral electrostatic potential differences were determined from the particle distribution functions obtained nearly simultaneously above and below the auroral acceleration region by.
CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda):  Satellite observations have established that parallel electric fields of both upward and downward current regions of the aurora are supported, at least in part, by strong double layers.
The purpose of this article is to examine the role of double layers in auroral electron acceleration using direct.  Magnetic conjugate observations by Cluster and DMSP F14 satellites are used to study the field lines of auroral arc.
Cluster is well above the acceleration region and observes upward keV ion beams and bipolar electric structures. The integrated potential at Cluster altitudes shows a dip that is consistent with the keV electron acceleration energy at low altitude.
On auroral magnetic field lines the electric field is strongly fluctuating both transverse and parallel to the magnetic field. The significance of these fluctuations for the auroral acceleration process is discussed.
A definition of dc electric fields is given in terms of their effects on charged particles. Fluctuations below several hertz are experienced as dc by typical auroral electrons if the acceleration length. ; Mizera and Fennell, ] that auroral particle acceleration parallel to the ambient magnetic field exists in the upward field-aligned current region.
Direct evidence of parallel electric fields in the auroral acceleration region was first reported by Mozeret al.  on the basis of data from the S satellite. These observations were. The theoretical fundamentals of auroral particle acceleration are based on the kinetic theory of plasmas, in particular the development of parallel electric fields.
These parallel electric fields can either be distributed along the magnetic field lines, often associated with the mirror geometry of the geomagnetic field, or concentrated into narrow regions of charge. The Electrodynamics particle accelerator are of two types they are-Linear accelerator: Linear particle accelerator in short linac accelerate particles along the straight line.
Here the subatomic particle or ion which is to be accelerated is subjected to a series of oscillating electric potential along the linear beamline. About Cookies, including instructions on how to turn off cookies if you wish to do so.
By continuing to browse this site you agree to us using cookies as described in About Cookies. Remove maintenance message. The filamentary structure of the FAC and subsequently of the associated accelerated particle flux is compatible with the auroral fine structures appearing during substorm expansion phase.
Acceleration by small AW packets. Field-aligned particle acceleration on auroral ﬁeld lines by interaction with transient density cavities stimulated by kinetic Alfv´en waves P.
Bespalov1, V. Misonova2, and S. Cowley 3 1Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St, Nizhny Novgorod, Russia. Information about the magnitude of the field-aligned potential drop along auroral field lines is usually derived from the velocity distribution of the particles.
fields, auroral acceleration.CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): There are recent observational indications (lack of convergent electric field signatures above the auroral oval at 4 RE altitude) that the U-shaped potential drop model for auroral acceleration is not applicable in all cases.
There is nevertheless much observational evidence favouring the U-shaped model .The auroral acceleration also affects the condition in which P = const along a field line, decreasing the ion pressure in the regions of upward field-aligned currents.
In contrast, in the regions of downward field-aligned currents, the pressure is generally conserved (see the review of Paschmann et al.