Mark IV Objectives

Low-energy coilguns of 1 to 10 joules are safe and easy to study. However, they are not impressive or even very useful, and they do not provide information about the typical operating regions where saturation and eddy currents become important.

Objectives

What happens to efficiency when we scale up from 6J to almost 200J? Does the addition of external iron improve efficiency compared to the typical, dismal 1 - 2% efficiency of air core coilguns?

The coilgun presented in this notebook is a medium-power demonstrator, intended for tabletop presentations to high school physics classes. This means it can have

• power from a wall socket – battery power is not important.
• visible components and construction – but some care must be made for safety and reliability.
• it should not easily expose dangerous voltages, but the “visible components” requirement may result in some exposed wiring.
• for simplicity, the technology is a single-stage switched-reluctance coilgun driven by capacitive discharge, similar to the Mark III coilgun.

We hope to get energy conversion efficiency of 2% or more, and speeds of 50 – 200 fps, using thin projectiles such as finishing nails.