How do electric fields accelerate ions in a mass spectrometer?

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Figure 1: An electron bombardment ion source in cross section. An electron beam is drawn from the filament and accelerated across the region in which the ions are formed and toward the electron trap. An electric field produced by the repeller forces the ion beam from the source through the exit slit. — mass spectrometry Figure 1: *An electron bombardment ion source in cross section.* An electron beam is drawn from the filament and accelerated across the region in which the ions are formed and toward the electron trap. An electric field produced by the repeller forces the ion beam from the source through the exit slit.

In a mass spectrometer, ions are accelerated into the mass analyzer by a system of electrostatic slits. This process utilizes electric fields to create a voltage drop, denoted as V, which imparts kinetic energy to the ions.12

When ions of charge z are accelerated through this voltage drop, they gain a kinetic energy equal to zV. This acceleration ensures that the ions enter the mass analyzer with a specific kinetic energy, which is a fundamental step in many types of mass spectrometry, such as magnetic sector analysis, where it allows for the separation of ions based on their mass-to-charge ratios.21