Absorption measurements on a low-pressure inductively coupled argon/mercury discharge for lighting purposes: 2. Electron density and temperature

Typical values for the electron density and temperature in the Philips QL lamp are obtained from the radially resolved measurements of the gas temperature profile and the density of the lowest argon metastable state, as presented in a previous paper (Jonkers J et al 1997 J. Phys. D: Appl. Phys. 30 1928-33). The results agree very well with the electron density and temperature as found by solving the electron particle and energy balance equations. For increasing argon filling pressure a lower electron temperature and a higher electron density are found, which are due to an increased residence time of the charged particles. It is also shown that in the QL lamp serious depletion of mercury occurs.