Propagation of ionization waves during ignition of fluorescent lamps

The propagation of the first ionization wave in a compact fluorescent lamp ( T4 tube with standard electrodes) during ignition was investigated for various initial dc-voltages ( both polarities measured against ground) and gas compositions ( with and without mercury). In addition the effect of the presence of a fluorescent powder coating was studied. The propagation velocity of the initial wave was measured by an assembly of photomultipliers installed along the tube, which detected the light emitted by the wave head. The propagation was found to be faster for positive than for negative polarity. This effect is explained involving processes in the electrode region as well as in the wave head. Waves propagate faster in the presence of a fluorescent powder coating than without it and gases of lighter mass show a faster propagation than gases with higher mass.