Experimental investigations on moving striations in a 50 Hz ac fluorescent lamp

Experimental investigations on moving striations in a low frequency ac fluorescent lamp are carried out. Preliminary experimental results reveal that moving striations in the lamp do not originate in the cathode region; rather, they have a close relationship to the cold spot temperature of the tube. Photos from high-speed CCD camera and measurement with monochromator indicate that striations only appear on the rising edge of the light signal from the lamp. Relatively high density of metastable Ar density and correlated step-wise ionization are hereby considered to be the possible reasons for the appearance of striated instabilities