Abstract
This thesis describes an experimental study of a field-reversed compact torus configuration which is generated and sustained by a rotating magnetic field. Earlier studies of this so-called `rotamak` concept used rotating magnetic fields of limited duration ({approx}15 {mu}s). The rotating magnetic field is produced by feeding RF currents, dephased by 90 deg., through two orthogonal Helmholtz coils which are wound around the outside of a spherical Pyrex vacuum vessel. Line generators are used to supply the RF current pulses. Experiments are performed using an argon plasma. From measurements of the driven toroidal current, two rotamak operating modes are identified. Detailed poloidal flux contour measurements prove that these modes are associated with either a closed magnetic field line, compact torus configuration or an open magnetic field line, mirror-like structure. In the compact torus configuration the driven toroidal current is shown to vary linearly with the magnitude of the externally applied equilibrium field. For the same initial conditions of filling pressure and externally applied equilibrium field, the plasma discharges are highly reproducible. The magnetic structures of the discharges are studied in detail for three such sets of initial conditions. In particular, poloidal flux contours are derived for each of the three conditions.
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Citation Formats
Durance, G.
The magnetic field structure of Rotamak discharges.
Australia: N. p.,
1983.
Web.
Durance, G.
The magnetic field structure of Rotamak discharges.
Australia.
Durance, G.
1983.
"The magnetic field structure of Rotamak discharges."
Australia.
@misc{etde_10154410,
title = {The magnetic field structure of Rotamak discharges}
author = {Durance, G}
abstractNote = {This thesis describes an experimental study of a field-reversed compact torus configuration which is generated and sustained by a rotating magnetic field. Earlier studies of this so-called `rotamak` concept used rotating magnetic fields of limited duration ({approx}15 {mu}s). The rotating magnetic field is produced by feeding RF currents, dephased by 90 deg., through two orthogonal Helmholtz coils which are wound around the outside of a spherical Pyrex vacuum vessel. Line generators are used to supply the RF current pulses. Experiments are performed using an argon plasma. From measurements of the driven toroidal current, two rotamak operating modes are identified. Detailed poloidal flux contour measurements prove that these modes are associated with either a closed magnetic field line, compact torus configuration or an open magnetic field line, mirror-like structure. In the compact torus configuration the driven toroidal current is shown to vary linearly with the magnitude of the externally applied equilibrium field. For the same initial conditions of filling pressure and externally applied equilibrium field, the plasma discharges are highly reproducible. The magnetic structures of the discharges are studied in detail for three such sets of initial conditions. In particular, poloidal flux contours are derived for each of the three conditions. Although no toroidal magnetic field is externally imposed in these experiments, under certain conditions a toroidal field is observed to be present. The toroidal field is in opposite directions in the upper and lower halves of the minor cross section. Measurements of the input power into the plasma show that this power is largely determined by the characteristics of the line-generators. The variation of this input power with time can explain all the features observed in the plasma discharges. The effects of a conducting `shell` around the vacuum vessel are also investigated. 97 refs., 72 figs., ills.}
place = {Australia}
year = {1983}
month = {Oct}
}
title = {The magnetic field structure of Rotamak discharges}
author = {Durance, G}
abstractNote = {This thesis describes an experimental study of a field-reversed compact torus configuration which is generated and sustained by a rotating magnetic field. Earlier studies of this so-called `rotamak` concept used rotating magnetic fields of limited duration ({approx}15 {mu}s). The rotating magnetic field is produced by feeding RF currents, dephased by 90 deg., through two orthogonal Helmholtz coils which are wound around the outside of a spherical Pyrex vacuum vessel. Line generators are used to supply the RF current pulses. Experiments are performed using an argon plasma. From measurements of the driven toroidal current, two rotamak operating modes are identified. Detailed poloidal flux contour measurements prove that these modes are associated with either a closed magnetic field line, compact torus configuration or an open magnetic field line, mirror-like structure. In the compact torus configuration the driven toroidal current is shown to vary linearly with the magnitude of the externally applied equilibrium field. For the same initial conditions of filling pressure and externally applied equilibrium field, the plasma discharges are highly reproducible. The magnetic structures of the discharges are studied in detail for three such sets of initial conditions. In particular, poloidal flux contours are derived for each of the three conditions. Although no toroidal magnetic field is externally imposed in these experiments, under certain conditions a toroidal field is observed to be present. The toroidal field is in opposite directions in the upper and lower halves of the minor cross section. Measurements of the input power into the plasma show that this power is largely determined by the characteristics of the line-generators. The variation of this input power with time can explain all the features observed in the plasma discharges. The effects of a conducting `shell` around the vacuum vessel are also investigated. 97 refs., 72 figs., ills.}
place = {Australia}
year = {1983}
month = {Oct}
}