Senior Honors Thesis

Railguns promise to make space travel and weapons systems much more efficient for the future. I conducted a project to skim the surface of railgun physics and design. I first started by constructing a small railgun as a proof-of-concept. I then delved deeper into the physics of operation by measuring and modeling the magnetic field associated with the operation of the device. The model railgun had all of the basic components of much larger, more complicated devices. It consisted of a pair of rails, a bank of powerful capacitors, a charging circuit, and an AC power source. When the capacitors were charged to 60 volts, I estimated the force on the projectile to be Newtons. Unfortunately, this was not enough force to overcome friction forces as well as tertiary " welding " of the projectile to the rails. In order to understand the basic physics principles behind the operation of the railgun, I measured the magnetic field produced by the rails. The field produced by a single rail was very non-uniform, revealing weaknesses in my initial rail design. I then conducted the same experiment, but with a solid wire. This produced the expected magnetic field, which was relatively small on the ends, with the maximum in the center of the length of wire. This taught me that a solid wire produces a desirable magnetic field, rather than my initial design that had many air-filled voids within the rails. With the knowledge gleaned from this immersion into railgun physics, I will be able to better design similar devices in the future with a greater understanding of magnetic field production. Figure 1: Diagram of railgun principle of operation (Harris, 2005). ________________________________ 8 Figure 2: The railgun model. The VariAC and polypipe launch tube are to the left of the device itself. ___ 13 Figure 3: Railgun charge/discharge circuit