Homodyne interferometry using a phase rotator for calibration of sine-cosine phase detection of a 70 GHz probe beam through a plasma.

Homodyne interferometry using a motorized phase rotator for calibration of sine-cosine detection of the phase shift of a 70 GHz probe beam through a plasma has been developed. Four interferometers based on this interferometry have been installed on the low aspect ratio torus experiment (LATE) device with four horizontal probe beams on the mid-plane, which has measured the line-integrated electron densities with a time resolution of 10 µs and a resolution of line-integrated density of 5 × 1015 m-2.

Individual fundamental mode dependence of H2O vibrational excitation in the 6-8 eV resonance region by electron impact.

Resonance phenomena in the bending (010), symmetric (100), and asymmetric (001) stretching vibrational modes in water (H(2)O) molecules have been investigated by measuring differential cross sections (DCSs) at fixed energy losses of 0.43, 0.46, 0.49, and 0.51 eV while sweeping the impact energies from 1.6 to 10 eV, at angles 60 degrees and 90 degrees, using a crossed-beam method. No resonancelike enhanced features have been observed in the study of the (010) mode. In the DCSs for the combined (100+001) mode, a single broad hump was observed at each angle, whose position shifts towards the higher energy side with increasing scattering angle, a feature typical of the interference profiles previously observed in a study of the (301) vibrational mode. DCSs for the (001) mode exhibited a rather isotropic angular distribution with no evidence of resonances. However, enhancement of DCSs were indeed observed for the (100) mode, at the energy loss of 0.46 eV, which is attributable to the A(1) symmetry resonance that was studied by Seng and Linder [J. Phys. B 9, 2539 (1976)], with a typical s-wave characteristic angular distribution. Theoretical analysis based on the continuum multiple-scattering approach has been carried out to provide rationale to the experimental results.

Electron scattering from tetrafluoroethylene.

We report experimental results for electron scattering from tetrafluoroethylene, C2F4, obtained from measurements in two laboratories. An extensive set of differential, integral, and momentum transfer cross sections is provided for elastic scattering for incident electron energies from 1 to 100 eV and inelastic (vibrational excitation) scattering for incident electron energies at 3, 6, 7.5, 8, and 15 eV, and for scattering angles ranging from 10 degrees to 130 degrees. To highlight the role of intermediate negative ions (resonances) in the scattering process we have also measured excitation functions for elastic scattering and vibrational excitation of the ground electronic state of C2F4 for incident energies between 1.5 and 20 eV. Our results are compared with recent theoretical calculations and a limited number of other experimental results.