Focal Length for E-M Lens

BACKGROUND

This was the mid-semester project completed for my first-year second term Integrated Course Block (ICB) class at Olin. 
ICB is Olin's innovative and constantly evolving introduction to vector calculus and E+M physics that emphasizes numerical simulation, rigorous analysis, and communication of technical ideas.

COLLABORATORS

Marc Sweetgall, Olin College '10

ABSTRACT

Often used in electron microscopy, an electromagnetic lens utilizes the magnetic field generated by a coil of current-carrying wire to focus a beam of electrons onto a desired point. In this work, we propose a simple model of an electromagnetic lens, apply the optical concept of focal length to the electromagnetic domain, and propose two distinct methods for calculating focal length using a numerical simulation of the lens. We then use the results of systematic experimentation with the simulation to determine how the focal length of a given model lens depends mathematically upon the lens’ geometry, the applied current, and the velocity of the electron beam.

FULL TEXT

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Mike Hughes,
Jan 13, 2009, 11:17 AM
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