Effect of magnetic field distortions on gyroresonance at low L values

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA02202· OSTI ID:6787589

Friedel, R H.W.; Hughes, A R.W. ^[1]

---

1. Univ. of Natal, Durban (South Africa)

From fully relativistic test particle simulations of the gyroresonance interaction between energetic electrons and whistler mode waves in the magnetosphere it is known that pitch angle diffusion due to this interaction becomes less and less effective at low L values, requiring very large wave amplitudes ([approximately]100 nT) for significant pitch angle changes ([Delta][alpha] > 1[degrees]). Such pitch angle changes are needed to produce the wave-induced electron precipitation as observed through the Trimpi events which have been reported at low latitudes. Our computer simulation has been extended to model background field distortions which may alter the curvature of the field line in such a way as to enhance the interaction efficiency. In general, flattening of the field line in the region near resonance enhances the interaction considerably, with a possible best case threefold increase in interaction time when compared to a undisturbed (dipole) field configuration. Our results indicate that pitch angle diffusion due to gyroresonance can only be significant at low L during periods of field line distortion, such as dayside compression or in the presence of Pc 4 or Pc 5 pulsations and various cavity mode oscillations. 15 refs., 7 figs., 2 tabs.

• OSTI ID: 6787589
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:A2; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLITUDES
CHARGED-PARTICLE PRECIPITATION
COMPRESSION
CONFIGURATION
DIFFUSION
EFFICIENCY
ELECTROMAGNETIC RADIATION
ELECTRON PRECIPITATION
ELECTRONS
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY SOURCES
FERMIONS
GYROFREQUENCY
INCLINATION
LEPTONS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELD RIPPLES
MAGNETIC FIELDS
NOISE
OSCILLATIONS
POWER
PULSATIONS
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
RELATIVISTIC RANGE
RENEWABLE ENERGY SOURCES
RESONANCE
SCATTERING
SIMULATION
WAVE POWER
WHISTLERS