Electron beam ion trap

[1] The positive ions produced in the region where the atoms intercept the electron beam are tightly confined in their motion by the strong attraction exerted by the negative charge of the electron beam.

Therefore, they orbit around the electron beam, crossing it frequently and giving rise to further collisions and ionization.

[2] The strong charge needed for radial confinement of the ions requires large electron beam currents of tens up to hundreds of milliampere.

To avoid charge reduction of ions by collisions with neutral atoms from which they can capture electrons, the vacuum in the apparatus is usually maintained at UHV levels, with typical pressure values of only 10−12 torr, (~10−10 pascal).

EBITs are used to investigate the fundamental properties of highly charged ions e. g. by photon spectroscopy in particular in the context of relativistic atomic structure theory and quantum electrodynamics (QED).

Schematics of an electron beam ion trap. Red: electron source filament, blue: electron beam, black: electrodes , green: magnet. The thin line represents the electric potential along the axis.