Equilibrium Charge Distribution of Energetic Nitrogen Ions

Abstract

The equilibrium charge distribution of nitrogen ions in Formvar was measured as a function of the nitrogen energy from 6 to 26 Mev. The fringing magnetic field of the cyclotron was used to separate the charge groups resulting from the passage of the nitrogen ion beam through Formvar foils of sufficient thickness to insure an equilibrium charge distribution. Over the energy range investigated, the ionic charge is distributed primarily between four, five, six, and seven electron charges. The percentage of completely stripped ions varies from 42 percent at 26 Mev to 6 percent at 11 Mev. The ratio of the electron loss to capture cross section between ${\mathrm{N}}^{7+}$ and ${\mathrm{N}}^{6+}$ as well as between ${\mathrm{N}}^{6+}$ and ${\mathrm{N}}^{5+}$ is proportional to $V^{4.0}$, whereas between ${\mathrm{N}}^{5+}$ and ${\mathrm{N}}^{4+}$ the ratio is proportional to $V^{2.9}$. This ratio is unity for ${\mathrm{N}}^{6+}$ and ${\mathrm{N}}^{7+}$ at approximately 28.2 Mev, and for ${\mathrm{N}}^{5+}$ and ${\mathrm{N}}^{6+}$ at 13.3 Mev.