Collisional ionization ofCq+byHe2+and its applications in the inertial controlled fusion diagnostics

Abstract

The ionization process in collisions of ${\mathrm{He}}^{2+}$ with ${\mathrm{C}}^{q+}$ $(q=0--5)$ is investigated using a continuum-distorted-wave eikonal-initial-state approximation. Total and single- and double-differential cross sections for $1s$ and $2s$ electrons are calculated for projectile energies from $30\phantom{\rule{0.3em}{0ex}}\mathrm{keV}∕\mathrm{u}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}10\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{u}$. From the double-differential cross sections at an electron-ejection angle of $\ensuremath{\theta}=0\ifmmode^\circ\else\textdegree\fi{}$, the variation of ionization mechanisms with $q$ has been studied and their dependences on the projectile energies and the electron subshells are also discussed. It is found that in the whole energy range considered, the absolute values of soft collision (SC) and binary encounter (BE) peaks decrease with increasing $q$. For the lower incident energies, the electron capture to the projectile continuum (ECC) peak, as well as SC and BE peaks, decreases with increasing $q$. For the higher incident energies $(>1\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{u})$, the absolute value of the ECC peak increases with increasing $q$, so that the crossings of cross sections appear for ${\mathrm{C}}^{q+}$ with different $q$. This can be explained by the matching of velocities between the projectile and the initially bound active electron in the target. Finally, by comparing the ionization rate coefficients for $K$-shell electrons of ${\mathrm{C}}^{q+}$ by ion and electron impacts in an environment of inertial controlled fusion (ICF), the possibility to diagnose the ${\mathrm{He}}^{2+}$ distribution in ICF by the characteristic $K\ensuremath{\alpha}$ spectrum of ${\mathrm{C}}^{q+}$ is investigated.