Mass Spectrometer Filaments

In a mass spectrometer, the filament serves as a key component within the ionization source, facilitating the generation of ions from sample molecules through techniques such as electron impact ionization (EI) or chemical ionization (CI). Typically composed of materials like tungsten due to its high melting point and efficient electron emission when heated, the filament operates by emitting electrons via thermionic emission when heated to a high temperature. In EI, these electrons are accelerated towards sample molecules, inducing ionization through collisions, while in CI, they collide with reagent gas molecules to form ions, which then react with the sample to cause ionization. Precise temperature control of the filament is crucial to maintaining optimal ionization conditions, ensuring efficient ion generation without filament degradation.