electric sector

The electric sector is a device constructed of curved,  parallel metal plates that creates an electrostatic field  perpendicular to the ion path. The sector (or analyzer) selects  and focuses ions of the same kinetic energy. The electric  sector does not separate ions according to mass or charge,  and therefore is always used in conjunction with a magnetic  analyzer, often in a double-focusing mass spectrometer. The  electric sector is also sometimes called an electrostatic sector  or electrostatic analyzer.