Plasma shift of the He iiPαline

We have measured the shift of the He i i 4685.7-Å line at electron density ranging from 2.5×${10}^{17}$ to 18.8×${10}^{17}$ ${\mathrm{cm}}^{\mathrm{-}3}$ and electron temperature between 8 and 10.5 eV. The plasma was produced in a Z-pinch discharge. Systematic red shifts linear in density are observed. The experimental results are in agreement with the best-fit curve of earlier results by Pittman and Fleurier obtained at lower electron densities and temperatures.