Engineering topics

Mueller, P

Publications and source records attributed to Mueller, P.

4 records

DOE OSTI2011

Optical excitation and decay dynamics of ytterbium atoms embedded in a solid neon matrix.

Neutral ytterbium atoms embedded in solid neon qualitatively retain the structure of free atoms. Despite the atom-solid interaction, the 6s6p {sup 3}P{sub 0} level is found to remain metastable with its lifetimes determined to be in the range of ten to hundreds of seconds. The atomic population can be almost completely transferred between the ground level and the metastable level via optical excitation and spontaneous decay. The dynamics of this process is examined and is used to explicitly demonstrate that the transition broadening mechanism is homogeneous.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

{sup 39}Ar Detection at the 10{sup -16} Isotopic Abundance Level with Atom Trap Trace Analysis

Atom trap trace analysis, a laser-based atom counting method, has been applied to analyze atmospheric {sup 39}Ar (half-life=269 yr), a cosmogenic isotope with an isotopic abundance of 8x10{sup -16}. In addition to the superior selectivity demonstrated in this work, the counting rate and efficiency of atom trap trace analysis have been improved by 2 orders of magnitude over prior results. The significant applications of this new analytical capability lie in radioisotope dating of ice and water samples and in the development of dark matter detectors.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2011

Spectroscopic study of the cycling transition 4s[3/2]{sub 2}-4p[5/2]{sub 3} at 811.8 nm in {sup 39}Ar: Hyperfine structure and isotope shift

Doppler-free saturated absorption spectroscopy is performed on an enriched radioactive {sup 39}Ar sample. The spectrum of the 3s{sup 2}3p{sup 5}4s[3/2]{sub 2}-3s{sup 2}3p{sup 5}4p[5/2]{sub 3} cycling transition at 811.8 nm is recorded, and its isotope shift between {sup 39}Ar and {sup 40}Ar is derived. The hyperfine coupling constants A and B for both the 4s[3/2]{sub 2} and 4p[5/2]{sub 3} energy levels in {sup 39}Ar are also determined. The results partially disagree with a recently published measurement of the same transition. Based on earlier measurements as well as the current work, the isotope shift and hyperfine structure of the corresponding transition in {sup 37}Ar are also calculated. These spectroscopic data are essential for the realization of laser trapping and cooling of {sup 37,39}Ar.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2010

Correlation reflectometry at TEXTOR

In high temperature fusion plasmas the transport of energy and particles is commonly believed to be driven by turbulence. Turbulence quantities as correlation length and decorrelation time are important for the confinement properties of a plasma. Besides other diagnostics, correlation reflectometry has proven to be a suitable tool for the measurement of turbulence properties. At the medium sized Toroidal EXperiment for Technical Oriented Research (TEXTOR) the existing correlation reflectometry has been recently upgraded. A new reflectometer based on a microwave synthesizer has been developed and installed for the investigation of turbulence properties in a fusion plasma. Together with the existing reflectometer the measurement of radial correlation length and decorrelation time becomes available. Both reflectometers are computer controlled and allow to program individual frequency sequences and the duration of each frequency step. With the existing poloidal antenna array at {theta}=0 deg. and on top of the vacuum vessel, the system allows the measurement of radial correlation and poloidal correlations at the same time. First experiments have been performed and the results on the radial correlation length of density fluctuations in a fusion plasma are presented.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗