Energy and angular distribution of auroral particles resulting from time-varying acceleration

It is generally accepted that the ''magnetic-field-aligned'' charged particles, that occur in some forms of auroral precipitation, have been collimated by an acceleration parallel to the geomagnetic field lines, within a few thousand kilometres of the earth's surface. Static electric fields parallel to the magnetic field lines have frequently been invoked to account for this acceleration. The consequences of such a static electric field are examined