degausser; demagnetizer
A device that removes unwanted magnetism from objects, such as CRT monitors, magnetic tapes, or tools.
For old CRT televisions, a degausser is sometimes used to fix color unevenness.
I erased the data on the magnetic tape by running it through a demagnetizer.
Compound of 消磁 (demagnetization) and 器 (device). The exact historical derivation is uncertain, but the term is a straightforward technical coinage.