Magnetohydrodynamic Modelling of Supersonic Jets and Colliding Blast Waves for Laboratory Astrophysics Investigation
Author(s)
Marocchino, Alberto
Type
Thesis
Abstract
The thesis is related to laboratory astrophysics, and investigates with this technique,
the launching mechanism for young stellar object jets and the interaction
of two supernovae remnant in the Sedov-Taylor regime. Recent experiments performed
at Imperial College on the pulsed-power magpie facility have successfully
shown the formation of magnetically driven radiatively cooled plasmas jets formed
from radial wire arrays, which are relevant to studying the launching mechanisms
of astrophysical jets [A. Ciardi, et al. Phys. Plasmas 14, p056501 (2007)]. The
experiments have been now extended to study episodic mass ejection ( 25 ns [F.
A. Suzuki-Vidal, et al. 49th Annual Meeting of the Division of Plasma Physics,
UO4.00007 (2007)]) and the interaction of jets and magnetic bubbles with an ambient
gas. The dynamics of the interaction is investigated through three-dimensional
resistive magneto-hydrodynamic simulations using the code gorgon [A. Ciardi, et
al. Phys. Plasmas 14, p056501 (2007) – J.P. Chittenden, et al. Plasma Phys. Control.
Fusion 46 B457 (2004)]. In particular ablation of the cathode is investigated
numerically to explain the periodicity and subsequent formation of multiple bubbles.
Comparison with experiments is offered to validate the results. The complex
structure of the magnetic field is investigated, the conservation of the magnetic flux
is explained and the consequent confinement offered to the central jet. Furthermore
the interaction of the plasma outflows with an ambient gas is investigated. The formation
of shocks in the ambient gas, as well as the formation of three-dimensional
Mach stems is analyzed. In addition, recent experiment at Imperial College performed
by the QOLS group, by laser-heating a medium of atomic clusters [R. A.
Smith, et al. 2007 Plasma Phys. Control. Fusion 49 B117-B124 (2007)], shows the capability to create plasmas with sufficiently high energy densities to launch strong
shocks. Interactions between high-Mach number shock waves are believed to be
responsible for many of the complex, turbulent structures seen in astrophysical objects
including supernova remnants. The experiment of two colliding Sedov-Taylor
regime blast-waves is modelled. Detailed 3D numerical modeling is performed in
order to study the importance of thermal conduction, rarefaction waves, refractive
shock waves and complex three-dimensional mach stem formation. The simulated
data are benchmark against a three-dimensional tomography image (newly developed
experimental technique). The collision of two blast-waves should reproduce
the non uniform interstellar medium where supernovas normally expand.
the launching mechanism for young stellar object jets and the interaction
of two supernovae remnant in the Sedov-Taylor regime. Recent experiments performed
at Imperial College on the pulsed-power magpie facility have successfully
shown the formation of magnetically driven radiatively cooled plasmas jets formed
from radial wire arrays, which are relevant to studying the launching mechanisms
of astrophysical jets [A. Ciardi, et al. Phys. Plasmas 14, p056501 (2007)]. The
experiments have been now extended to study episodic mass ejection ( 25 ns [F.
A. Suzuki-Vidal, et al. 49th Annual Meeting of the Division of Plasma Physics,
UO4.00007 (2007)]) and the interaction of jets and magnetic bubbles with an ambient
gas. The dynamics of the interaction is investigated through three-dimensional
resistive magneto-hydrodynamic simulations using the code gorgon [A. Ciardi, et
al. Phys. Plasmas 14, p056501 (2007) – J.P. Chittenden, et al. Plasma Phys. Control.
Fusion 46 B457 (2004)]. In particular ablation of the cathode is investigated
numerically to explain the periodicity and subsequent formation of multiple bubbles.
Comparison with experiments is offered to validate the results. The complex
structure of the magnetic field is investigated, the conservation of the magnetic flux
is explained and the consequent confinement offered to the central jet. Furthermore
the interaction of the plasma outflows with an ambient gas is investigated. The formation
of shocks in the ambient gas, as well as the formation of three-dimensional
Mach stems is analyzed. In addition, recent experiment at Imperial College performed
by the QOLS group, by laser-heating a medium of atomic clusters [R. A.
Smith, et al. 2007 Plasma Phys. Control. Fusion 49 B117-B124 (2007)], shows the capability to create plasmas with sufficiently high energy densities to launch strong
shocks. Interactions between high-Mach number shock waves are believed to be
responsible for many of the complex, turbulent structures seen in astrophysical objects
including supernova remnants. The experiment of two colliding Sedov-Taylor
regime blast-waves is modelled. Detailed 3D numerical modeling is performed in
order to study the importance of thermal conduction, rarefaction waves, refractive
shock waves and complex three-dimensional mach stem formation. The simulated
data are benchmark against a three-dimensional tomography image (newly developed
experimental technique). The collision of two blast-waves should reproduce
the non uniform interstellar medium where supernovas normally expand.
Date Issued
2009-02
Date Awarded
2009
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Creator
Marocchino, Alberto
Publisher Department
Department of Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)