Kinetics of higher lying Rb states after, Pulsed excitation of the D2 transition in the Presence of Helium

Author

Austin J. Wallerstein

Date of Award

3-24-2016

Document Type

Thesis

Degree Name

Master of Science in Applied Physics

Department

Department of Engineering Physics

First Advisor

Glen P. Perram, PhD.

Abstract

The Diode Pumped Alkali Laser (DPAL) is a high power, three-level laser system that employs diode bars to optically excite an alkali metal vapor. It lases along the D₁ transition, between the two lowest energy levels, ²P_1/2 and ²S_1/2. Higher lying energy states are produced at higher population density via energy pooling and multiphoton processes. Pulsed laser excitation of rubidium at approximately 1 MW=cm² has been studied at helium pressure up to 900 Torr. Emissions from energy states as high as 82D suggests modest ionization, though these intensities decrease drastically at buffer gas pressures above 250 Torr. Blue emission from the 6²P→5²S_1/2 transition and red emission from the 5²D→5²P transition indicate population in these upper states that persists at all helium pressures used in this experiment. A basic kinetic model was created to describe the concentration at these higher lying states. Optical trapping is severe at temperatures above 450 K. Diffusion of the rubidium is very slow, requiring mixing times exceed 45 minutes.

AFIT Designator

AFIT-ENP-MS-16-M-087

DTIC Accession Number

AD1053942

Recommended Citation

Wallerstein, Austin J., "Kinetics of higher lying Rb states after, Pulsed excitation of the D2 transition in the Presence of Helium" (2016). Theses and Dissertations. 352.
https://scholar.afit.edu/etd/352