High-intensity lithium beam for Zeeman spectroscopy

The Zeeman splitting of neutral lithium introduced to a hot plasma as a beam may be used to determine both the magnitude and direction of the local magnetic field. Dye lasers can improve the sensitivity of the method, either by resonance fluorescence or by intracavity absorption. A limit on the applicability of this diagnostic is set by the lithium density in the plasma. A high density, 80-kV lithium beam has been developed to access plasmas of larger dimension and/or higher densities, or to permit measurements with better time resolution than with previous beams. The beam utilizes a high density lithium ion source. Diagnostics include 2-D ion beam profiling, Faraday cup, magnetic analyzer, and a ‘‘pepperpot’’ probe for measurements of beam intensity, composition, and divergence. Beam currents can exceed 10 mA in a ≤2-cm-diameter beam with a divergence of several milliradians.