TITLE:  The X-ray Aurora

ABSTRACT:  This talk will review the physics of the bremsstrahlung X-ray emission process. The classical cross section and emission rates from thick targets will be presented. Observations of terrestrial X-ray emissions are a very useful method for remote sensing energetic electron precipitation. Auroral x-rays were first discovered in 1961 by Kinsey Anderson [Anderson and Milton, 1964]. Auroral electrons are usually energetic enough to produce X-rays detectable at balloon altitudes in auroral breakup forms. This talk will begin by reviewing the use of rocket launched, parachute deployed X-ray counters to study the transport of auroral X-rays through the atmosphere. Other important X-ray phenomena include microbursts, thought to be the signature of wave induced particle precipitation associated with discrete wave bursts. In recent years, attention has focused on relativistic electron precipitation in the vicinity of the plasmapause.