New techniques in the study of ion processes in weak plasmas
Abstract
The understanding of both natural and technical weak plasmas requires a detailed understanding of ion-molecule reaction dynamics, often under exotic conditions, including plasmas under nonequilibrium conditions. In modeling such plasmas it is not uncommon to make use of binary reaction rates measured at room temperature and low pressure, either directly or with some sort of extrapolation, to high temperatures and pressures. Measurements made at hyperthermal energies provide a guide. The Air Force Research Laboratory has made significant contributions to the understanding of these plasma environments over an unprecedented range of temperature (80-1800 K) and pressure (0.001 to 760 Torr). These results are provided by the laboratory's selected-ion flow-tube (SIFT), flowing-afterglow Langmuir-probe (FALP), guided ion-beam (GIB), high-temperature flowing-afterglow (HTFA), and turbulent ion flow tube (TIFT). In addition, state-selected ion-molecule reactions are being studied using the pulsed-field ionization photoelectron/secondary-ion coincidence method at the Advanced Light Source. Several examples of work carried out with these apparatuses will be described, e.g., online optical detection of labile reactants coupled with a flow tube reactor. We will also describe computational results for thermodynamic properties of hydrocarbon positive ions which appear as common products of reactions in our work.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..GECXF1001M