This thesis describes physics research carried out at the Columbia Neutral Torus (CNT) stellarator after its adaptation from a non-neutral plasma experiment to a device relevant to magnetic fusion energy research. Results are presented in the areas of plasma heating and related topics (microwave-assisted plasma start-up, overdense heating, inversion of stellarator images), as well as to stellarator stability and related topics (high β, error fields). This thesis also describes the engineering improvements which enabled the said adaptation of CNT. The first step of that process involved the installation of a low-power, pulsed 2.45 GHz magnetron. In those initial experiments it was found that the simultaneous use of microwave start-up and of an emissive hot cathode resulted in non-linearly increased electron densities, implying a synergy between the two start-up methods. Then, a 10 kW, 2.45 GHz heating system was commissioned including a custom-designed transmission line and launch antenna. Highly overdense plasmas (a factor of 4 above the cutoff density) were obtained with this system, both for O-mode and X-mode polarization. The analysis of Langmuir probe profiles of density and temperature required the accurate mapping of the minor radius in the plasma, which motivated a study of CNT error fields. This resulted in a new numerical method for inferring coil misalignments from flux surface measurements. The improved knowledge of the actual magnetic field geometry of CNT permitted to develop and successfully apply an inversion technique to experimental plasma images. This technique (“onion peeling”) reconstructs radial emissivity profiles, and can be considered a 3D generalization of Abel inversion. Finally, simulations of high-β plasma equilibria in different CNT magnetic configurations indicate that (1) ballooning stability limits should be accessible at volume-averaged β as low as 0.9% and (2) ballooning-stable β values as high as 3.0% should be attainable with heating powers as low as 40-100 kW and 1-3 MW respectively, according to stellarator energy confinement scaling laws.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 176 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis--Utrecht. / Vita. Errata slip inserted. Includes bibliographical references (p. 87-89).

Not available / text

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains vi, 206 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Thesis--Utrecht. / Vita. Errata slip inserted. Includes bibliographical references (p. 87-89).

Thesis (Ph.D.)--University of California, Berkeley, 1961. / "Controlled Thermonuclear Processes, UC-20" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 68).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1994. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 233-244).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 247-250).