Date of Award

Spring 2006

Document Type

Restricted Thesis

Terms of Use

© 2006 Jerome Fung. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Physics & Astronomy Department

First Advisor

Michael R. Brown

Abstract

The Swarthmore Spheromak Experiment (SSX) studies magnetic reconnect ion by merging co- and counterhelicity spheromaks. Typical plasma parameters include electron density ne ~ 10¹⁵ cm⁻³, temperature Ti + Te ~ 30 eV, and magnetic fields |B| ~ 0.1 T. This thesis documents the construction of a new high-resolution ion Doppler spectroscopy (IDS) diagnostic. The SSX IDS system features a 1.33 m Czerny-Turner spectrometer with a 316 grooves/mm echelle grating and a 32-channel photomultiplier tube array. On any shot, we can observe any of 10 different chords through the plasma with submicrosecond time resolution and an instrument temperature ~ 3 eV. Current studies have focused on the evolution of the carbon III 229.687 nm line which we observe at 25th order, with dispersion 0.0085 nm/mm using 3.7x magnifying exit optics. We have determined the time dependence of flow velocities and ion temperatures in the plasma. We have also performed Abel inversions to determine radial profiles of the plasma emissivity. In addition, we have observed near-Alfvènic bi-directional flows due to reconnection. These results, as well as a possible model for the flows based on shear, are presented.

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