Date of this Version
Lederer, J. Electron Beam Dispersion Compensator Using a Wien Filter. Undergraduate Honors Thesis. University of Nebraska-Lincoln. March 2021.
When an electron beam travels through space, it spreads out over time which impedes the ability to work with short electron pulses in the lab. A Wien filter is a device consisting of perpendicular electric and magnetic fields which filters charged particles based on their velocities. For a specific velocity, the two forces from the two fields in the filter cancel each other out letting charges with that velocity travel straight through the filter. Charges moving at other speeds are deflected as they have a net force applied to them from the filter. If a particle is deflected from the center line of the Wien filter, the charge will change its velocity due to the work done on it from the filter’s electric field. This can have the effect of focusing charges of different initial velocities at a focus point, and has the property that charges of different initial velocities take the same amount of time to reach the focus some distance away from the entrance of the filter. This project concerns the design of a Wien filter which will be designed, built, and tested to act as a dispersion compensator. The goal of this project is to show that the filter will lessen the natural spread of an electron pulse as it travels through space when compared to a pulse that is not acted on by the Wien filter.