Search

Your search keyword '"Scime, E. E."' showing total 98 results
Start Over Author "Scime, E. E."
98 results on '"Scime, E. E."'

73. Ion dynamics in helicon sources

Author

Kline, J. L., primary, Balkey, M. M., additional, Keiter, P. A., additional, Scime, E. E., additional, Keesee, A. M., additional, Sun, X., additional, Hardin, R., additional, Compton, C., additional, Boivin, R. F., additional, and Zintl, M. W., additional

Published
2003
Full Text
View/download PDF

91. Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device.

Author

Thakur, S. Chakraborty, Adriany, K., Gosselin, J. J., McKee, J., Scime, E. E., Sears, S. H., and Tynan, G. R.

Subjects
LASER-induced fluorescence, FLUORESCENCE spectroscopy, ION temperature, PHOTOLUMINESCENCE, LASER spectroscopy
Abstract

We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

92. E B energy-mass spectrograph for measurement of ions and neutral atoms.

Author

Funsten, McComas, D. d., and Scime, E. E.

Subjects
SPECTROGRAPHS, THOMSON scattering, ELECTRIC fields, MAGNETIC fields, PLASMA gases
Abstract

Describes a Thomson parabola spectrograph that utilizes an electric field parallel to a magnetic field and a two-dimensional imaging detector to uniquely identify the energy-per-charge and mass-per-charge distributions of plasma ions. Characteristics of the spectrograph; Removal of deviations of observed spectra; Applicability of the spectrograph for neutral atom identification.

Published
1997
Full Text
View/download PDF

93. Three-dimensional laser-induced fluorescence measurements in a helicon plasma.

Author

Hardin, R., Sun, X., and Scime, E. E.

Subjects
ARGON, HELICON, PLASMA gases, LASERS, FLUORESCENCE, STEPPING motors
Abstract

We describe a three-dimensional (3D) laser-induced fluorescence (LIF) diagnostic for argon ions in a helicon plasma source. With three different laser injection orientations at a single spatial location, LIF measurements are performed to determine the 3D ion temperature and the 3D ion flow vector. The measurement process is then repeated at multiple locations in a cross section of the plasma column to create a two-dimensional (2D) map of the 3D ion flow, the ion temperature, and metastable ion density. Scanning in the 2D plane is accomplished by mounting the injection and collection optics on stepping motor driven stages. [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
View/download PDF

95. The hot hELicon eXperiment (HELIX) and the large experiment on instabilities and anisotropy (LEIA).

Author

Scime, E. E., Keiter, P. A., Balkey, M. M., Kline, J. L., Sun, X., Keesee, A. M., Hardin, R. A., Biloiu, I. A., Houshmandyar, S., Chakraborty Thakur, S., Carr, J., Galante, M., McCarren, D., and Sears, S.

Subjects
*ANISOTROPY, *ION temperature, *HELICON, *LASER-induced fluorescence, *ELECTROSTATIC fields
Abstract

The West Virginia University Hot hELIcon eXperiment (HELIX) provides variable density and ion temperature plasmas, with controllable levels of thermal anisotropy, for space relevant laboratory experiments in the Large Experiment on Instabilities and Anisotropy (LEIA) as well as fundamental studies of helicon source physics in HELIX. Through auxiliary ion heating, the ion temperature anisotropy (T⊥/T∥) is variable from 1 to 20 for parallel plasma beta (β = 8πnkTi∥/B2) values that span the range of 0.0001 to 0.01 in LEIA. The ion velocity distribution function is measured throughout the discharge volume in steady-state and pulsed plasmas with laser induced fluorescence (LIF). The wavelengths of very short wavelength electrostatic fluctuations are measured with a coherent microwave scattering system. Operating at low neutral pressures triggers spontaneous formation of a current-free electric double layer. Ion acceleration through the double layer is detected through LIF. LIF-based velocity space tomography of the accelerated beam provides a two-dimensional mapping of the bulk and beam ion distribution functions. The driving frequency for the m = 1 helical antenna is continuously variable from 8.5 to 16 MHz and frequency dependent variations of the RF coupling to the plasma allow the spontaneously appearing double layers to be turned on and off without modifying the plasma collisionality or magnetic field geometry. Single and multi-species plasmas are created with argon, helium, nitrogen, krypton, and xenon. The noble gas plasmas have steep neutral density gradients, with ionization levels reaching 100% in the core of the plasma source. The large plasma density in the source enables the study of Aflvén waves in the HELIX device. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

97. Effects of Gap Width on Vacuum-Ultraviolet Transmission Through Submicrometer-Period, FreeStanding Transmission Gratings.

Author

Balkey MM, Scime EE, Schattenburg ML, and van Beek J

Abstract

The effects of gap width on the transmission coefficient of vacuum-ultraviolet light through submicrometer-period, freestanding transmission gratings are reported. Results from computations and an analytical waveguide model are shown to be consistent with experimental measurements. These results show that thin gratings with narrow gaps and thick gratings with wide gaps are equally effective at eliminating 121.6-nm radiation. The thin gratings with the narrow gaps have the advantage of better attenuation of shorter-wavelength radiation than the thick gratings with the larger gaps.

Published
1998
Full Text
View/download PDF

98. Extreme-ultraviolet polarization and filtering with gold transmission gratings.

Author

Scime EE, Anderson EH, McComas DJ, and Schattenburg ML

Abstract

The polarization and transmission characteristics of freestanding gold transmission gratings, with 200-nm periods, for extreme-ultraviolet (EUV) radiation (1 < 200 nm) have been measured. We find that EUV transmission through the gratings is dominated by the waveguide characteristics of the gratings and that polarization efficiencies of 90% for wavelengths of 121.6 nm are achievable. Both the EUV polarization and transmission properties are in good agreement with a complete vector, numerical solution of Maxwell's equations. The fraction of open area to total area of the grating has been measured using a 10-keV proton beam and was found to be in good agreement with the microscopic slit and wire dimensions that were obtained by scanning electron microscopy. The use of these gratings for particle measurements in the presence of intense EUV radiation is briefly discussed.

Published
1995
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results