De Simone, Gabriel A. (2018) Haces moleculares supersónicos en procesos de separación isotópica. / Supersonic molecular beams in isotope separation processes. Trabajo Especial Física, Universidad Nacional de Cuyo, Instituto Balseiro.
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Resumen en español
Dada su importancia en algunos métodos de separación isotópica asistida por láser, se estudió el proceso de formación de clusters en la expansión de un sistema de moléculas del tipo XF_6 (SF_6 y UF_6). Abordando el estudio del sistema desde la mecánica clásica y dada la importancia que en los procesos de separación tiene el estado vibracional de las moléculas, se propuso un mejor potencial intramolecular que los encontrados en la bibliografía. Este se ajustó a partir de las frecuencias de vibración experimentales de las moléculas. Se empleó dinámica molecular para validar el modelo y estudiar procesos fuera del equilibrio termodinámico. Se estudió la formación de clusters en la expansión libre de un gas de SF6. Se encontró que, al final de la expansión, sobrevive una proporción estable de clusters, que aumenta con la presión. Se vio que los clusters tendrían a formarse en las regiones con menor temperatura y mayor densidad. Con sistemas de 8 mil y 64 mil moléculas se obtuvieron resultados indistinguibles; solo se modificó la duración de los tiempos de relajación y la incerteza estadística de las determinaciones. Si bien la teoría cinética de gases no incluye la formación de clusters, los resultados obtenidos para las distribuciones de velocidades coincidían con los esperados a partir de esta teoría.
Resumen en inglés
Given its importance in some laser isotope separation methods, we studied cluster formation processes during the expansion of a XF_6 (SF_6 and UF_6) like molecule system. Using a classical mechanics approach and given the relevance of the molecular vibrational state in these separation processes, we present an improved intramolecular potential function compared to those found in previous works. We obtained the potential parameters from measured molecule vibration frequencies. In order to test the force field and to study non-equilibrium processes, we employed Molecular Dynamics. We studied cluster formation during the free expasion of gaseous SF6. At the end of the expansion, we found that an amount of stable clusters had survived, which increased with pressure. We noticed that cluster formation was promoted in regions with lower temperature and higher density. Working with 8 thousand and 64 thousand molecule systems, we obtained identical results; only relaxation times and statistical uncertainty changed. Although clusters are not described in the frame of kinetic theory of gases, the obtained speed distributions agreed with those predicted by this theory.
| Tipo de objeto: | Tesis (Trabajo Especial Física) |
|---|---|
| Palabras Clave: | Expansion; Expansión; Isotope separation; Separación isotópica; Beams; Haces; [Laser] |
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| Materias: | Física > Física molecular Física > Óptica Física > Física atómica |
| Divisiones: | Gcia. de área de Investigación y aplicaciones no nucleares > Gcia. LASIE > Subgcia. de aplicaciones de tecnología láser |
| Código ID: | 761 |
| Depositado Por: | Tamara Cárcamo |
| Depositado En: | 10 Jul 2019 14:21 |
| Última Modificación: | 10 Jul 2019 14:21 |
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