| dc.contributor.author |
Petrović, Z. Lj. |
|
| dc.contributor.author |
Stojanović, V. |
|
| dc.contributor.author |
Nikitović, Ž. |
|
| dc.contributor.editor |
Popović, Luka Č. |
|
| dc.date.accessioned |
2011-01-10T11:50:01Z |
|
| dc.date.available |
2011-01-10T11:50:01Z |
|
| dc.date.issued |
2007 |
|
| dc.identifier.isbn |
978-86-80019-17-8 |
en_US |
| dc.identifier.uri |
http://hdl.handle.net/123456789/1460 |
|
| dc.description.provenance |
Submitted by Slavisha Milisavljevic (slavisha) on 2011-01-10T11:50:01Z
No. of bitstreams: 1
I12.pdf: 609692 bytes, checksum: b55ebd3723fbe56e5a74edf7ef541992 (MD5) |
en |
| dc.description.provenance |
Made available in DSpace on 2011-01-10T11:50:01Z (GMT). No. of bitstreams: 1
I12.pdf: 609692 bytes, checksum: b55ebd3723fbe56e5a74edf7ef541992 (MD5)
Previous issue date: 2007 |
en |
| dc.language.iso |
en |
en_US |
| dc.publisher |
Nenad Milovanović & Milan S. Dimitrijević, Astronomical Observatory, Belgrade |
en_US |
| dc.title |
ELECTRON, ION AND ATOM COLLISIONS LEADING TO ANOMALOUS DOPPLER BROADENING IN HYDROGEN AND HYDROGEN RARE GAS MIXTURES |
en_US |
| mf.subject.keywords |
The first interpretations of unusually high Doppler broadening of hydrogen lines in nonequilibrium
plasmas were based on possible dissociative processes, recombination and
excitation (Capelli et al. 1985). The experiments, especially the experiments performed in
Dc fields revealed a large asymmetric component with energies often exceeding the energy
available from the repulsive potentials of the dissociating molecules (Barbeau and Jolly
1990; Konjević and Kuraica 1992). The explanation of such results was sought and found
on the basis of high E/N swarm experiments (Petrović et al. 1992; Petrović and Phelps
1991) which show a large degree of excitation by fast neutrals formed in charge transfer
collisions with fast ions. At high E/N, which can be only achieved under breakdown
conditions to the left of the Paschen minimum, the mean free paths are sufficiently high to
allow large energy gain by ions. In addition it is possible to have reflection and
neutralization of ions with reflection as fast neutrals, which leads to different components
in blue and red wings of the Doppler profile (Petrović et al. 1992).
Some alternative explanations of anomalous Doppler profiles were offered in the
literature (Mills et al. 2002), but all reliable measurements performed so far (Jovićević et al.
2004; Tatarova et al. 2007) do not require more than a combination of dissociative
excitation (with a perhaps possible recombination as well playing some role) and
acceleration in high fields leading to heavy particle (predominantly fast neutral) excitation.
On the other hand, high E/N swarm DC experiment (Townsend regime discharge)
may be modeled directly and exactly as it does not require self consistent calculation of the
electric field and is thus open to a simple Monte Carlo simulation that may include
complexity at the level of representation of collisional events. In this paper we show revised
results of modeling of Doppler profiles by using a well tested Monte Carlo procedure and
revised models of heavy particle collisions. In particular we study the importance of fast
H2 and fast H particles, the effect of different models of angular distribution of particles
scattered of the surface and of the molecules and we study the role of the energy losses due
to vibrational excitation. |
|
| mf.document.pages |
38 |
en_US |
| mf.contributor.editor-in-chief |
Dimitrijević, S. Milan |
|