Ion-motion broadening of the<i>Δn=0</i>,<i>n=2</i>transitions of C v in a carbon laser-produced plasma

Abstract

We measured the line profiles of the \ensuremath{\Delta}n=0,n=2 lines of C v produced when a ruby laser was focused (\ensuremath{\ge}${10}^{12}$ W/${\mathrm{cm}}^{2}$) onto a polyethylene target. Line profiles were measured at 3 mm from the target surface where the electron density is of the order of ${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ as inferred from a folded wave-front shearing interferometric technique and the line profile of the 3434-A\r{} line of C vi. After fitting the data to profiles calculated considering the different Stark and Doppler contributions to the line, we found that the calculated profile for the 3526-A\r{} line of C v is considerably narrower than the experimental result and this discrepancy is common to all the \ensuremath{\Delta}n=0,n=2 lines. Judging from the fact that the ratio of the experimental widths of the different lines is proportional to the respective ratio of wavelengths this effect should be related to the ion motion. The presence of hydrodynamic turbulence causing the profile to have a large effective Doppler temperature approximately equal to 600 eV may explain this result.