Investigation of the lifetime of the upper laser level of Ar II $4р^2D_{5/2}$ based on the spontaneous emission in a coupled transition

The change in the lifetime of the upper laser level $4р^2D_{5/2}$ in the plasma of an argon laser is investigated using the spontaneous emission in a transition coupled with the laser transition. With a rise in the concentration of electrons from $10^{13}$ to $10^{14}$ cm$^{-3}$ the lifetime of the level is reduced from 10 to 4 nsec, which may be totally associated with the rise in the number of electron collisions.