UGResearch

Research Information

Title Analysis and Modeling of X-ray Microbursts
Download
 You must be registered and logged in to download research
Tell Others Share on Facebook
Forward Research
Type Thesis
Length 96 Pages
Area Physics
Advisor Dr. Robyn Millan
Composed 2004
Summary Abstract: The Earth’s radiation belts are made up of charged particles trapped by the geomagnetic field in two belts around the equator, ranging in altitude from just above the atmosphere to about seven earth radii (45,000 km). Movement of particles in this region follows a complex interaction among the particles, the geomagnetic field, and the electric and magnetic fields of the particles themselves. In more than fifty years since the discovery of the radiation belts, this motion has been only imperfectly explained. In particular, the processes responsible for regulating the number of high-energy particles in the radiation belts are not known. Understanding this phenomenon is critical to our technological society, since we depend on an increasing number of satellites whose functionality and communications can be adversely affected by energetic particles. The January, 2000 MAXIS balloon flight was designed to help explain one aspect of this process—the losses of energetic particles—by measuring X-ray bremsstrahlung radiation from energetic electrons precipitating into the atmosphere above Antarctica. During the flight, two types of events were observed: Longer duration, sustained bursts of X-rays, lasting tens of minutes, and periods of high frequency, short duration (less than 1 second) microbursts. The observations of this second class of events represent the first observations of X-ray microbursts with an instrument capable of detecting X-rays with energies above 1 MeV. In this thesis, the MAXIS microburst observations are analyzed, and are found to be universally low in energy, consistent with electron precipitation below ∼ 100 keV. In order to constrain possible scattering mechanisms, and to help predict future observations, a model is proposed for the motion of energetic particles in the drift loss cone for these events. This model suggests that microbursts are due exclusively to locally-scattered particles, and demonstrates the need for future experiments involving several balloons at different locations to investigate the evolution of microbursts in space and time.

Author Information

Name Andrew Hunter
Picture PIC
Contact Send Message
College Dartmouth
Grad Year 2004
Extended Info Not Provided