Non adiabatic energization of electrons and ions by electric field gradients.
Abstract
The approximate conservation of the magnetic moment of a charged particle moving in a magnetic field is fundamentally important to the physics of space plasmas. It is the basis of the adiabatic theory of particle motion which serves as the backbone of modelling the motion of plasmas in the magnetosphere. Although the approximate nature of the adiabatic theory is well understood its specific limitations are seldom discussed in detail. In this presentation we describe a process of non-adiabatic energy gain or loss by particles moving in the perpendicular magnetic and electric fields both of which have spatial gradients. Under certain conditions these particles experience non-adiabatic gain or loss of energy which is associated with non-conservation of their magnetic moment. The effect is proportional to the gyroradius, so it is usually small, especially for the electrons, however this effect is secular in nature and may become substantial, even for the electrons, if the appropriate conditions exist for a sufficient length of time. The conditions for this violation of adiabaticity are not rare, they occur whenever the gradients of the electric and magnetic fields are parallel. For example, this effect applies to a commonly used scenario of substorm injection generation by an earthward propagating electromagnetic pulse.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSM33C3589K
- Keywords:
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- 2716 Energetic particles: precipitating;
- MAGNETOSPHERIC PHYSICSDE: 2720 Energetic particles: trapped;
- MAGNETOSPHERIC PHYSICSDE: 2772 Plasma waves and instabilities;
- MAGNETOSPHERIC PHYSICSDE: 2774 Radiation belts;
- MAGNETOSPHERIC PHYSICS