High Quality Content by WIKIPEDIA articles! A quadrupole ion trap or quadrupole ion storage trap (QUISTOR) exists in both linear and 3D (Paul Trap, QIT) varieties and refers to an ion trap that uses constant DC and radio frequency (RF) oscillating AC electric fields to trap ions. It is commonly used as a component of a mass spectrometer. The invention of the 3D quadrupole ion trap itself is attributed to Wolfgang Paul who shared the Nobel Prize in Physics in 1989 for this work.