The absorption coefficients of 1.15- and 3.39-μm radiation for a homogeneous H-He plasma have been measured in the temperature range $14\times {10}^3<~T<~20\times {10}^3°$K and electron density range $8\times {10}^{16}<~n_e<~5\times {10}^{17}$ ${\mathrm{cm}}^{-3\mathrm{}}$, where the major absorption mechanisms are electron-ion inverse bremsstrahlung and neutral-atom photoionization. The measured values compare well with those obtained from theoretical calculations for a gas in thermodynamic equilibrium.

• Received 31 January 1972

DOI:https://doi.org/10.1103/PhysRevLett.28.1435