Secondary-Electron Yield on Copper-Beryllium forH+,H2+,H3+,H0,H20, andH30

Abstract

Experimental secondary-electron yields for ${\mathrm{H}}^{+}$, $\mathrm{H}_2^{}{}_{}{}^{+}$, and $\mathrm{H}_3^{}{}_{}{}^{+}$ incident on copper-beryllium at 60° increase continuously from about 3 at 2 keV to 5.9 at 55 keV for ${\mathrm{H}}^{+}$; to 8.5 at 55 keV for $\mathrm{H}_2^{}{}_{}{}^{+}$; and to 10.8 at 55 keV for $\mathrm{H}_3^{}{}_{}{}^{+}$. At an angle of incidence 0°-72° corresponding values are about 1.7 times larger. Thus the yield increases approximately as $sec\theta$. The ratio of yield ${\delta }_0$ for neutral particles (obtained by charge transfer) to yield ${\delta }_1$ for ions was determined by a calorimetric measurement of the incident beam power. Neutrals yield more electrons than ions, and the ratio is only slightly dependent on energy. At 25 keV, the ratio $\frac{{\delta }_0}{{\delta }_1}$ is 1.14 for ${\mathrm{H}}^{+}$, 1.26 for $\mathrm{H}_2^{}{}_{}{}^{+}$, and 1.41 for $\mathrm{H}_3^{}{}_{}{}^{+}$. The secondary-electron and positive-ion energy spectra were measured for both neutrals and ions. The two types of particles gave the same spectra. The atomic stopping cross section for protons on copper was extrapolated down to 2 keV.