Alternative interpretation of ion-ring distribution observed by the S3-3 satellite. Technical report

Technical Report · Wed May 15 04:00:00 EDT 1985

OSTI ID:5073631

Gorney, D J

Recently, theoretical interest has grown in possible plasma wave instabilities arising from free energy in auroral ion distributions, and a number of ion-mode instabilities have been identified. These instabilities typically rely on positive slopes in the ion's velocity distribution parallel (del f/del v(sub par) > 0) or perpendicular (del f/del v(sub perp) > 0) to the magnetic field. Upflowing ion beams generated by electrical potential drops along auroral field lines are obvious candidates for the parallel (beam) instability, while ion conics have been treated in the limit of the flute-mode instability, assuming that a positive perpendicular gradient exists. However, ion conics are not responsible for the condition del f/del v(sub perp) > 0. Downflowing ion beam distributions can have del f/del v(sub perp) > 0 and therefore might lead to flute mode instability. Examples of both conics and downflowing beams are presented, showing that only the downflowing component leads to significant del f/del v(sub perp) > 0, while ion conics generally have del f/del v(sub perp) < 0 and are themselves stable to the flute mode.

• Research Organization: Aerospace Corp., El Segundo, CA (USA). Space Sciences Lab.
• OSTI ID: 5073631
• Report Number(s): AD-A-157655/2/XAB; TR-0084A(5940-05)-3
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
&amp; Magetospheric Phenomena
640203 -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
BEAMS
DISTRIBUTION
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ENERGY
FREE ENERGY
INSTABILITY
ION BEAMS
ION RINGS
MAGNETIC FIELDS
PHYSICAL PROPERTIES
PLASMA INSTABILITY
PLASMA WAVES
SATELLITES
THERMODYNAMIC PROPERTIES
VELOCITY