Observation of Electron Drift in an Electrostatic Particle Accelerator and a CST

Researchers: Jonathan LaPoint, Niklas Austermann, Sam Winn

Our experiment aims to model the electron drift patterns through use of a physical e/m apparatus as well as a CST simulation of the same accelerator. The e/m apparatus, consisting of two coils opposite the tube each with an electrical current as well as two plates, one positive and one negative, propels electrons from the electron gun to the electromagnetic field present in the tube. Ionization with the argon gas inside of the tube produces a dim yet visible blue effect that is essential in tracing the path of the electron. Nevertheless, the experiment aims to further explore how alterations made to the electromagnetic field, caused by changes in the orientation of the surrounding coils, could change the electron’s path and drift.

Methodology (for the first part of the experiment)

The voltage of the particle accelerator’s power supply was set to 6.0 V with the current set to 1.5 A (DC is set to 250 volts). The base of the particle accelerator was modified using 3D printed pieces (design pictured below) in order to maximize the potential tilt of the Helmholtz coils to ± 15.0° in either direction. The 3D-printed turning mechanism, used to fix the coils to rotating bases secured to the secondary wooden base via a swivel, was attached to each coil. 

Then, 25% of the top plate was cut off and attached separately to the main top plate. The main top plate was reinserted into the apparatus with a tilt of approximately 45°, and the cut off section of the top plate was reinserted horizontally, centered and parallel to the tube. The apparatus was then turned on, and the BxB electron drift was observed.

With the CST simulation, we will attempt to model the tilt of the coils, and the separation of the top plate. We will observe whether our observed field results align with the results predicted by the simulation.

Figure I: The setup of the e/m apparatus described above, with the separated top plate and tilted coils. The top plate is fixed to the coils with duct tape but this is subject to change. At the moment, 3-D printed parts are the most feasible solution to securely fix the top plates.

Figure II: Results of the BxB electron drift from the setup depicted above. This image 

Figure III: We created a PVC frame to drape a black curtain over our apparatus, in order to obtain better photos. 

Figure IV: This was our photography setup prior to the addition of a PVC pipe framework. Sam is under the cloth, using a slow shutter app to get better lighted photos of the electron beam.