Pulsed-periodic discharge in cesium as an effective source of light

Abstract

The spectrum of visible radiation from an inhomogeneous cesium-plasma column is evaluated in the approximation of locally thermodynamically equilibrium plasma. The plasma parameters correspond to a pulsed-periodic low-power discharge at pressures of 0.1–1.0 atm and the axial temperature T=5500 K. Under these conditions, the visible spectrum of the cesium plasma changes from discrete (line) to continuous as the pressure varies from 0.1 to 1.0 atm. This is associated largely with an increase in the intensity of the 6P and 5D recombination continua and an appreciable shift of the thresholds of the continua toward larger wavelengths (by ≈100 nm for 6P and by ≈150 nm for 5D) when the plasma density rises to ≈4×1017 cm−3. In this case, the optical thickness of the plasma column approaches unity and the average luminous flux per unit length of the arc column is close to 6500 lm/cm at the column radius R=2 mm and a duty ratio of 0.1.