In sci-fi works, electromagnetic guns often appear as future weapons.
電磁砲の原理は、ローレンツ力を利用して弾丸を加速させることだ。
The principle of a railgun is to accelerate a projectile using Lorentz force.
Compound of 電磁 (electromagnetic) and 砲 (gun, cannon). A modern technical term, likely a calque from English 'electromagnetic gun'.