Experiments in electron-ion collisions

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1988

OSTI ID:5149903

Timmer, C A

In order to better understand astrophysical, thermonuclear, and other plasmas, there is a need for data on electron-impact excitation, recombination, and ionization cross sections of ions. This work includes one of the first measurements of dielectronic recombination (DR) cross sections, and the first and only measurement of electric field enhancements of DR cross sections. Both of these measurements were made on Mg{sup +}. Results of the former experiment revealed a cross section that was an order of magnitude higher than predicted by theory at that time. These results spurred a flurry of theoretical activity, which eventually led this group to do the second DR experiment. Theory was developed to a point where agreement with data was within 20%. In other experiments, the electron-impact ionization cross sections of Al{sup +}, Cd{sup +}, and Hg{sup +} were measured. Effects of excitation-autoionization were looked for in each ion and found in the case of Al{sup +}. A large part of this work consisted of developing a new technique to measure electron-impact excitation cross sections, allowing measurements of transitions not possible until this time. To implement this method, a merged-beams apparatus was designed and built which detects nearly 100% of the inelastically scattered electrons instead of the customary photons. Tests were done showing that nearly all components of the system were operational. In the future, this apparatus will be used with an ion source capable of producing highly charged ions, with the intent of providing excitation data for these ions.

• Research Organization: Colorado Univ., Boulder, CO (USA)
• OSTI ID: 5149903
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ALUMINIUM IONS
ELECTRON-ION COLLISIONS
CADMIUM IONS
EXCITATION
IONIZATION
RECOMBINATION
MAGNESIUM IONS
MERCURY IONS
ASTROPHYSICS
CATIONS
CROSS SECTIONS
MEASURING INSTRUMENTS
MEASURING METHODS
PLASMA
THERMONUCLEAR REACTIONS
CHARGED PARTICLES
COLLISIONS
ELECTRON COLLISIONS
ENERGY-LEVEL TRANSITIONS
ION COLLISIONS
IONS
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
SYNTHESIS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena