Modelling Of Protostellar Jets Using Intense Lasers

Using telescopes such as the Hubble Space Telescope, astronomers observe parsec-scale plasma jets emerging from Young Stellar Objects and colliding with the interstellar medium, generating shock structures. A set of mathematically rigorous scaling transformations exists allowing dynamic scaled models of radiative, yet otherwise ideal, hydrodynamic flows to be created in the laboratory. In this thesis two experiments are presented in which plasma jets were produced using high-intensity lasers. In the first of these, the effects on jet collimation of radiative emission and the presence of a gaseous ambient medium were studied, with a view to learning about the effects of these factors on YSO jets by studying their scaled laboratory counterparts. The second experiment was designed to be similar to the first in order to investigate applying the scaling relations to scaling between laboratory experiments. Previous work in this area has shown that jets made in vacuo from materials with a higher mean atomic number form narrower, better-collimated jets (e.g. Shigemori 2000). Also, for jets propagating into a gas, shock structures similar to those seen in simulations of the interaction of a YSO jet with the interstellar medium have been observed (e.g. Nicolai 2008). In this thesis, both of these results are replicated, and the collimation work extended with a study of the collimation of jets in 50 mb He gas. The energies of the laser pulses used in the first experiment were over an order of magnitude lower than those used in previous studies of cylindrically-symmetric jets. This gives the replication and development of previous work added significance, showing that the same physics can be used to describe the behaviour of a plasma on a smaller energy scale and demonstrating that jet modelling experiments can potentially be done using university-scale laser facilities.

Name dc:type.qualificationname

Ph.D

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of York

Year dc:date.issued

2010

Author dc:creator

• Waugh, Jonathan Nicholas

Advisor dc:contributor.advisor

• Woolsey, Nigel C.

Identifier

uk.bl.ethos.534941

OAI identifier oai:identifier

oai:etheses.whiterose.ac.uk:1468