Determination of Optical-Field Ionization Dynamics in Plasmas through the Direct Measurement of the Optical Phase Change

Technical Report · Fri Jul 16 04:00:00 EDT 1999

DOI:https://doi.org/10.2172/759189· OSTI ID:759189

Taylor, A J; Omenetto, G; Rodriguez, G; Siders, C W; Siders, J L.W.; Downer, C

This is the final report of a three-year Laboratory Directed Research and Development (LDRD) Project at Los Alamos National Laboratory (LANL). The detailed dynamics of an atom in a strong laser field is rich in both interesting physics and potential applications. The goal of this project was to develop a technique for characterizing high-field laser-plasma interactions with femtosecond resolution based on the direct measurement of the phase change of an optical pulse. The authors developed the technique of Multi-pulse Interferometric Frequency Resolved Optical Gating (MI-FROG), which recovers (to all orders) the phase difference between pumped and unpumped probe pulses, enabling the determination of sub-pulsewidth time-resolved phase and frequency shifts impressed by a pump pulse on a weak probe pulse. Using MI-FROG, the authors obtained the first quantitative measurements of high-field ionization rates in noble gases and diatomic molecules. They obtained agreement between the measured ionization rates an d those calculated for the noble gases and diatomic nitrogen and hydrogen using a one-dimensional fluid model and rates derived from tunneling theory. However, much higher rates are measured for diatomic oxygen than predicted by tunneling theory calculations.

• Research Organization: Los Alamos National Lab., NM (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 759189
• Report Number(s): LA-UR-99-3036
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ATOMS
DYNAMICS
FLUIDS
HYDROGEN
INTERACTIONS
IONIZATION
LASERS
MOLECULES
NITROGEN
OXYGEN
PHASE TRANSFORMATIONS
PROBES
RARE GASES
RESOLUTION
TUNNELING