Kinetic Energy of Trapped Ions Cooled by Buffer Gas

The average kinetic energy of ⁴⁰Ca⁺ ions is measured by the method of evaporating ions in an rf ion trap. The kinetic energy of the ion ⁴⁰Ca⁺ varies from 0.5 eV to 0.2 eV with changing buffer gas pressure from 10^-7 mbar to 10^-5 mbar. The Brownian motion model is also introduced to calculate the average kinetic energy of the trapped ions.