Effect of a pulsed power supply on the ultra violet radiation and electrical characteristics of low pressure mercury discharge

This work deals with the application of a pulsed power supply for pile driving of a low pressure mercury discharge (LPD). The influence of the pulsed current power supply on the electrical properties and the spectral radiant flux emitted by a germicidal UV lamp has been investigated, both experimentally and theoretically. A Self Consistent Col- lisional-Radiative model SCCR is described to understand the behavior of the plasma characteristics operated in a pulsed mode. This model includes elastic and inelastic processes as well as ambipolar diffusion. The output gives the whole macroscopic plasma properties such as the electric field strength, the electron temperature, the energy transfers of the various collision processes and the radiation output. To evaluate the energy emitted in the UV bandwidth, a photometric system composed of an integrating cylinder, UV radiometer, a spectrograph and a CCD camera is mounted. This study provides a framework for the design of a pulsed current power supply which features single or multiple pulses superimposed on a low-frequency square wave. Reasonable agreement has been obtained between the experimental data and the results of calculations which take the above processes into account.