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Department Library

1999

Scott E. Perry (Honors Thesis, March 1999, Advisor: Neil Rasband )

Abstract

1993

Christian Y. Cardall (Honors Thesis, July 1993, Advisor: Neil Rasband )

Abstract

1990

Yao Hui Xu (PhD Dissertation, April 1990, Advisor: Neil Rasband )

Abstract

After a brief review of the history and the recent developments of oscillating Field Current Drive (OFCD), a gamma profile for the modified Bessel function model is suggested and a 0-D simulation equation based on helicity balance is derived. Implications of the relaxation effect for the experimental results of OFCD are considered. Based on the nonlinear relation between the injected helicity and the driven toroidal current, current saturation effects are investigated for various field models. A method for using OFCD as a tool to study plasma properties is discussed, and as an example the resistivity profile is considered. The sensitivity of this method to model assumptions is examined.

1982

Darrell Lee Peterson (PhD Dissertation, August 1982, Advisor: Neil Rasband )

Abstract

The subjects of equilibrium and dynamic stability to ideal local modes in the MHD model are addressed for the BYU Topolotron. A computer code designed to correctly produce the Topolotron features of limit cycles and two channels of toroidal current within the plasma solves the Grad-Shafranov equation of plasma equilibrium using an inner-outer iteration technique. A variety of diffuse-boundary MHD equilibria have been computed for an axisymmetric idealization of the BYU Topolotron. A numerical instability to up-down asymmetry was found and has suggested a possible similar dynamic instability.The stability of the computed equilibria with respect to ideal local MHD stability, in particular the ballooning instability, has bene examined with a computer code adapted to apply to the Topolotron equilibria. It has been found that equilibria stable to local modes exist and a comparison with Tokamak equilibria indicates that the Topolotron equilibria have comparable stability. The results from the stability code have suggested modifications to the device that will improve the likelihood of producing a stable plasma.

1974

Richard G. Hier (Masters Thesis, January 1974, Advisor: Neil Rasband )

Abstract

The absorption of gravitational radiation energy by mechanical systems is investigated herein. The present state of the art is briefly reviewed, and the growing inadequacy of the calculation of the cross section for absorption of gravity waves by the resonant modes of the cylinder using the one-dimensional rod approximation is discussed. The general method for the computation of cross sections when given the detector eigensolutions is displayed; and, using the solution of the one-dimensional rod approximation, cross sections are calculated as a referent. The approximate Pochhammer-Chree solutions are then proffered as a possible temporary alternative to the enormously more difficult exact solutions for the purpose of obtaining better cross section values. Presented here in full form are the results of a detailed numerical study of cross sections in the various types of longitudinal axisymmetic modes of the Pochhammer-Chree approximation. Significant gains over the previous approximation are indicated, including a much greater capacity for spectrum sampling, increases in sensitivity are certain frequencies, and some interesting possibilities for new ways of looking at cylinder response.