Mass Driver

A mass driver (マスドライバー) is an electromagnetic catapult which is used to accelerate and launch payloads at high speeds.

Principles
A mass driver is a catapult launch system, primarily consisting of a path which payloads travel down, powerful electromagnets positioned down along that path and a magnetizable holder containing a payload. The rows of electromagnets are used to accelerate the payload down the path, which then continues travelling after leaving the path on the momentum it has acquired.

Toaru Majutsu to Kagaku no Ensemble
A mass driver in an Academy City cooperative institution in Australia is used to send a biopod to Academy City, with the city attempting to shoot it down using Debris Storm.