English: Power spectral density of bremsstrahlung emission due to electron-ion collisions in a plasma [1]. As described on that page, the power is evaluated in the quantum limit (${\displaystyle T_{e}>Z^{2}27.2}$ eV). The solid blue curve is the full formula involving the exponential integral, while the dashed red curve is the approximate logarithmic form for ${\displaystyle \hbar \omega \ll T_{e}}$. We take ${\displaystyle \hbar \omega _{p}/T_{e}=0.1}$.