Shift of the He II Pαline in high density plasmas

The authors have measured the shift of the line He II 468.57 nm at electron densities ranging from 1 to 6*10 23 m -3 at 4 eV. A value of 0.0155 nm at 10 23 m -3 was measured. A linear variation with the density is observed. Three different effects supposed to be responsible for the shift are reviewed. Comparison of the authors' results with theory is precluded by the large uncertainty concerning the plasma polarisation shift. Good agreement is observed with previous measurements.