Abstract
23P levels in a helium discharge are depleted by absorption of a pulsed laser beam tuned to the 43D-23P transition. The relaxation towards their equilibrium population is analysed from the time variation of the transmitted part of a CW laser beam probing the 23P population at 5875 AA (33D-23P transition). This relaxation is ascribed to the radiative and collisional cascades starting from the 43D and 43F levels.