Relation of electron scattering cross-sections to drift measurement in noble gases
Author(s)
Stacey, Blake (Blake C.)
DownloadFull printable version (2.287Mb)
Other Contributors
Massachusetts Institute of Technology. Dept. of Physics.
Advisor
Ulrich J. Becker.
Terms of use
Metadata
Show full item recordAbstract
We investigate the classic "inverse problem" of extracting collision and scattering cross sections from measurements of electron swarm behavior. A Monte Carlo technique for simulating electron motion through a gas of isotropic scatterers is presented, providing a simplified version of Biagi's MAGBOLTZ algorithm. Using this Monte Carlo software, we examine the thermalization of electron swarms, focusing on their drift velocity and informational entropy, providing justification for a set of analytic expressions for drift measurements which are valid in the hydrodynamic regime. These expressions are then used to estimate the ⁴He scattering cross section, first by a simple grid interpolation and then through a genetic algorithm (GA). This technique demonstrates that the 4He momentum-transfer cross section in the 0-7 eV range is approximately 6.5 [Angstrom]², with a peak near 2 eV, in agreement with literature values. Empirical cross sections are also presented for Xe and He:CH₄(90:10).
Description
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2005. Includes bibliographical references (leaves 59-62).
Date issued
2005Department
Massachusetts Institute of Technology. Dept. of Physics.Publisher
Massachusetts Institute of Technology
Keywords
Physics.