The continuous absorption coefficients for the bound-free and free-free transitions of H and H<sup>-</sup> as well as the total absorption coefficients are given for hydrogen plasmas of 1, 10, 30, 100, and 300 atmos pressure and temperatures of 10 080, 12 600, and 16 800°K in the wavelength range from 2000 to 40 000 A. In order to calculate the free-free transitions of H- the tables of Chandrasekhar and Breen have been extended to include θ=0.4 and θ=0.3. The results of these calculations, namely the free-free absorption coefficients for H- per neutral hydrogen atom in the ground state and unit electron pressure, are given for θ=0.4 and θ=0.3. Finally, from the total absorption coefficients, the continuous emission from a 1-cm thick layer of the hydrogen plasmas under consideration has been derived. It is shown that for certain temperatures and pressures the continuous emission becomes so strong that the blackbody intensity of the corresponding temperature is reached for all wavelengths under consideration. This makes the plasma, in particular, useful for photolysis work and absorption spectroscopy.
FRITHJOF MASTRUP, "Continuous Emission of Hydrogen Plasmas," J. Opt. Soc. Am. 50, 32-35 (1960)