Examination of the feasibility of detection of calcium evaporation from a type B dispenser cathode by laser induced phenomena.
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Authors
Eason, Virginia L.
Subjects
Advisors
Luke, T.E.
Date of Issue
1983-03
Date
March 1983
Publisher
Air Force Institute of Technology, Air University
Language
Abstract
Three methods, laser induced resonance fluorescence, excitation to a shorter lived level from a metastable level, and ionization spectroscopy are examined for feasibility of detecting and measuring calcium evaporation from a type B cathode. Laser induced fluorescence of the 4s(1)S(0)<—> 4p(1)P(1) (4226 A) transition of calcium is the most promising and the easiest to implement. Ionization of the calcium atoms after they have been excited by a laser to the metastable (3)P(1) state is feasible but requires redesign of extant equipment to implement. Excitation to a shorter lived level from the metastable (3)P(1) state is feasible for the transition from the (3)D(2) (4435 A) level and not feasible for the (3)S(1) (6122 A) transition. Sensitized fluorescence and stimulated emission involving excited calcium atoms is examined and discarded. Calcium evaporation rates are semiquantitatively related to barium evaporation rates to take advantage of the more extensive literature on the latter. Limited experimental data is presented which indicates that an observation reported by another researcher of the barium evaporation rate decreasing after the cathode exceeded 1200° K is not attributable to pulse pile up error in the photon counting system but is most likely attributable to a cathode physics phenomenon. An argument for switching the course of future experiments from evaporation rates vs lifetime studies to evaporation rate vs cathode temperature is made. All calculations are based upon vi experimental results of previous workers and are order of magnitude rather than a rigorous treatment.
Type
Thesis
Description
This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library Collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title.
Series/Report No
Department
Engineering
Organization
Air Force Institute of Technology, Air University
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NPS Report Number
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Citation
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.