Event Title

Anomalous Resistivity and Non-Thermal Features in the Auroral Plasma

Location

Yosemite National Park

Start Date

2-8-1974 8:00 AM

End Date

2-8-1974 8:45 AM

Description

A general discussion of the concept of anomalous resistivity will be given. The conditions under which anomalous resistivity may or may not occur in the magnetospheric-ionospheric system will also be discussed. As a particular example we will look at the high energy, low density electron beams which have been repeatedly seen propagating in a stable fashion in the auroral zones. We will show that stabilization of beam instabilities is possible, in a definite plasma parameter regime, owing to non-linearly induced parametric instabilities, i. e. the oscillating two stream instability. The reason for the possibility of stabilization is that, at a certain level of plasma waves in resonance with the beam, a transfer of the generated oscillations takes place by means of this instability into a phase velocity region which is non-resonant with the beam. These oscillations can then interact with the tail end of the ambient electron distribution. When such a process takes place in a time interval less than the characteristic time for generation of waves by the beam, the level of the wave energy affecting the beam remains low and the beam state remains relatively unchanged.

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Feb 8th, 8:00 AM Feb 8th, 8:45 AM

Anomalous Resistivity and Non-Thermal Features in the Auroral Plasma

Yosemite National Park

A general discussion of the concept of anomalous resistivity will be given. The conditions under which anomalous resistivity may or may not occur in the magnetospheric-ionospheric system will also be discussed. As a particular example we will look at the high energy, low density electron beams which have been repeatedly seen propagating in a stable fashion in the auroral zones. We will show that stabilization of beam instabilities is possible, in a definite plasma parameter regime, owing to non-linearly induced parametric instabilities, i. e. the oscillating two stream instability. The reason for the possibility of stabilization is that, at a certain level of plasma waves in resonance with the beam, a transfer of the generated oscillations takes place by means of this instability into a phase velocity region which is non-resonant with the beam. These oscillations can then interact with the tail end of the ambient electron distribution. When such a process takes place in a time interval less than the characteristic time for generation of waves by the beam, the level of the wave energy affecting the beam remains low and the beam state remains relatively unchanged.