1,352 research outputs found
Galactic Wind in the Nearby Starburst Galaxy NGC 253 Observed with the Kyoto3DII Fabry-Perot Mode
We have observed the central region of the nearby starburst galaxy NGC 253
with the Kyoto Tridimensional Spectrograph II (Kyoto3DII) Fabry-Perot mode in
order to investigate the properties of its galactic wind. Since this galaxy has
a large inclination, it is easy to observe its galactic wind. We produced the
Ha, [N II]6583, and [S II]6716,6731 images, as well as those line ratio maps.
The [N II]/Ha ratio in the galactic wind region is larger than those in H II
regions in the galactic disk. The [N II]/Ha ratio in the southeastern filament,
a part of the galactic wind, is the largest and reaches about 1.5. These large
[N II]/Ha ratios are explained by shock ionization/excitation. Using the [S
II]/Ha ratio map, we spatially separate the galactic wind region from the
starburst region. The kinetic energy of the galactic wind can be sufficiently
supplied by supernovae in a starburst region in the galactic center. The shape
of the galactic wind and the line ratio maps are non-axisymmetric about the
galactic minor axis, which is also seen in M82. In the [N II]6583/[S
II]6716,6731 map, the positions with large ratios coincide with the positions
of star clusters found in the Hubble Space Telescope (HST) observation. This
means that intense star formation causes strong nitrogen enrichment in these
regions. Our unique data of the line ratio maps including [S II] lines have
demonstrated their effectiveness for clearly distinguishing between shocked gas
regions and starburst regions, determining the extent of galactic wind and its
mass and kinetic energy, and discovering regions with enhanced nitrogen
abundance.Comment: 22 pages, 5 figures, 1 table, accepted for publication in Ap
Equilibrium and relaxation of particulate charge in fluorocarbon plasmas
Charging of micron-size particulates, often appearing in fluorocarbon plasma etching experiments, is considered. It is shown that in inductively coupled and microwave slot-excited plasmas of C4F8 and Ar gas mixtures, the equilibrium particle charge and charge relaxation processes are controlled by a combination of microscopic electron, atomic (Ar+ and F+), and molecular ion (CF3+, CF2+, and CF+) currents. The impact of molecular ion currents on the particulate charging and charge relaxation processes is analyzed. It is revealed that in low-power (<0.5 kW) microwave slot-excited plasmas, the impact of the combined molecular ion current to the total positive microscopic current on the particle can be as high as 40%. The particulate charge relaxation rate in fluorocarbon plasmas appears to exceed 108 s−1, which is almost one order of magnitude higher than that from purely argon plasmas. This can be attributed to the impact of positive currents of fluorocarbon molecular ions, as well as to the electron density fluctuations with particle charge, associated with electron capture and release by the particulates
Investigation of the ion dose non-uniformity caused by sheath-lens focusing effect on silicon wafers
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