Total Ionization in Nitrogen by Heavy Ions of Energies 25 to 50 keV

Abstract

The total ionization produced by ions stopped in nitrogen gas has been measured in the energy range 25-50 keV. The measurements were made using an ion accelerator for producing the incident particles and a cylindrical ionization chamber with a differentially pumped open window. The following ions were studied: ${\mathrm{H}}^{+}$, ${\mathrm{He}}^{+}$, ${\mathrm{C}}^{+}$, ${\mathrm{N}}^{+}$, ${\mathrm{O}}^{+}$, and ${\mathrm{Ar}}^{+}$. The average energy loss per ion pair, $W$, ranges from 34.6 eV for 25-keV protons to 115.2 eV for 25-keV argon ions. A calculation indicates that a large part of the variation of $W$ with initial ion energy and atomic species may be attributed to the variation of the energy ultimately going into the kinetic energy of the atoms of the gas.