Our everyday experience of aged and defective fluorescent tubes or bulbs informs us that they may
flicker and emit a clicking sound while struggling to light up. In this article, the physical
mechanisms controlling the initial illumination of a functioning fluorescent tube are investigated
using a simple and affordable experimental setup. Thermionic emission from the electrodes of the
tube controls the startup of fluorescent tubes. The origin of the faulty startup of aged fluorescent
tubes is discussed and flickering regimes using functional tubes are artificially produced using a
dedicated setup that decreases electron emission by the thermionic effect in a controlled manner.
The physical parameters controlling the occurrence of flickering light are discussed, and their
temporal statistics are reported.