The Planck's character and temperature of visible radiation of a pulse-periodic discharge in cesium vapor

The radiation spectrum of pulse-periodic discharge in cesium vapor has been simulated in the framework of a two-temperature multifluid radiative gasdynamic model. It is established that, at a broad range of vapor pressures, the discharge spectrum exhibits a Planck character in a significant part of the visible spectral interval, which accounts for the high quality of color rendering in the discharge radiation. The relation between color temperature $T_c$ and electron temperature $T_0$ on the discharge axis is determined by radial optical thickness $\tau_R$ of the plasma column: $T_{c}\approx T_{0}$ at $\tau_{R}\approx$ 1, $T_{c}<T_{0}$ at $\tau_{R}<$ 1, and $T_{c}>T_{0}$ at $\tau_{R}>$ 1. As the vapor pressure increases from 83 to 1087 Torr, color rendering index $R_a$ of the discharge radiation changes from 95 to 98 and the color temperature grows from 3600 to 5200 K.