Energy distribution of electrons under axial motion in a quadrupole Penning trap

Abstract

We present results of the energy distribution function of trapped electrons through a measurement of their axial oscillation in a quadrupole Penning trap. Electrons emitted from a thoriated tungsten filament with a range of energies (3–5 eV) are trapped in a low magnetic field quadrupole Penning trap. Subsequent to storage the trapped electrons are detected through monitoring their axial oscillations by an electronic tank circuit that is weakly coupled to the trap, by resonant energy transfer to the electrons. The technique, developed using LabVIEW, enables a direct measurement of the energy distribution function of the electrons in the trap. We obtain a normal distribution of energy, with a maximum that coincides with the potential applied on the electron filament, indicating that the energy distribution of electrons in the trap reflects the energy distribution of the thermionically emitted electrons from the filament.