Ion heating in an auroral potential structure

Free access article

Issue		A&A Volume 419, Number 3, June I 2004


Page(s)		793 - 799
Section		Astrophysical processes
DOI		http://dx.doi.org/10.1051/0004-6361:20034513

A&A 419, 793-799 (2004)
DOI: 10.1051/0004-6361:20034513

Ion heating in an auroral potential structure

A. Anastasiadis¹, I. A. Daglis¹ and C. Tsironis²

¹ National Observatory of Athens, Institute for Space Applications and Remote Sensing, 15236 Penteli, Greece
e-mail: daglis@space.noa.gr
² Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
e-mail: ctsironis@astro.auth.gr

(Received 15 October 2003 / Accepted 26 February 2004 )

Abstract
We investigate the interaction of O ⁺ ions with a one-dimensional potential well, using Hamiltonian formulation. Heating of plasma originating in the terrestrial ionosphere plays a catalytic role in solar-driven magnetic storms, which dissipate energy globally within the magnetosphere of the earth. An interesting candidate for ionospheric plasma heating is a potential well located at auroral arcs in the high-latitude magnetosphere. We consider a potential with an exponential form, having a characteristic length L_x. The oxygen ions drift towards the auroral arc in the presence of a constant magnetic field B_z and a constant electric field E_y. The orbits of individual ions for different initial conditions - phase angle and kinetic energy - are traced. Our results show that, depending upon the initial conditions, test particles can be either accelerated or decelerated. Furthermore, we perform a parametric study for the interactions of mono-energetic and Maxwellian type of initial ion distribution - using random phase angle injection of the particles - with respect to our main model parameter, the characteristic length of the potential L_x. We conclude that for characteristic lengths comparable to twice the ion gyroradius, the O ⁺ population is accelerated.

Key words: acceleration of particles -- plasmas

Offprint request: A. Anastasiadis, anastasi@space.noa.gr

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