Electron pitch angle scattering and the impulsive phase microwave and hard X-ray emission from solar flares

Journal Article · Tue Jun 01 00:00:00 EDT 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/159994· OSTI ID:6865231

Holman, G D; Kundu, M R; Papadopoulos, K

Observations and theoretical considerations have led to a model for impulsive phase flare emission involving the heating and acceleration of thermal electrons in the coronal part of a magnetic loop. The bulk of the heated gas is confined between conduction fronts, but particles with velocities a few times greater than the thermal velocity can escape into the lower part of the loop. We show that, when the electron gyrofrequency exceeds the plasma frequency, the escaping electrons are unstable to the generation of electrostatic plasma waves which scatter the particles in pitch angle to a nearly isotropic distribution. We show that this scattering can (i) enhance the microwave emission from the upper part of the loop and (ii), due to the Landau damping of both low and high phase velocity waves, can lead to one or two breaks in the impulsive phase hard X-ray spectrum.

• Research Organization: Astronomy Program, University of Maryland
• OSTI ID: 6865231
• Journal Information: Astrophys. J.; (United States), Vol. 257:1
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
SOLAR FLARES
ELECTRON PLASMA WAVES
HYDROMAGNETIC WAVES
MATHEMATICAL MODELS
MICROWAVE RADIATION
PLASMA WAVES
X RADIATION
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
SOLAR ACTIVITY
640104* - Astrophysics & Cosmology- Solar Phenomena
700108 - Fusion Energy- Plasma Research- Wave Phenomena