The causes of oscillations or pulsations of terminal voltage and dis charge current in fluorescent lamp were investigated.
Essentially, the oscillations are regular relaxation oscillations expected from the stability conditions of general discharge forms.
The one oscillation is due to periodical variation of anode fall, its frequency is from few hundreds cycles to few kilo-cycles, at special condition to about sixty thousand s cycles. It is called anode oscillation.(fig.1) The other oscillation occurs at the tran sient state of alternating current discharge, its frequency is generally high, to few hundreds kilo-cycles. It is a sort of intermittent discharge locally occurring, called cathode oscillation.(fig. 8). Between two oscillations direct relation does not exist, but plasma properties, stationary and transient, are important to each oscillation and relate them in this sense.
The origins of radio noise generated from fluorescent lamp are almost two above-mentioned oscillations directly or indirectly and proper design can stop the generation of these oscillations.

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The transient voltage induced for starting a fluorescent lamp depends on the performance characteristics of a starter which can be represented by its glow resistance.
Since the glow resistance varies with the current, showing the negative characteristics, the FL circuit in which a starter operates, is generally non linear.
But our experiments proved that the instantaneous values of the transient voltage calculated under the assumption of the glow resistance being constant, are approximately in agreement with the actually measured values on oscillograms, within such a short time as 0.3-0.4 milli seconds after contact separation of a starter.
For this reason, the crest value of the transient voltage expected to occur within the above mentioned period, can be calculated with the glow resistance measured on a starter.
In this case, it is to be considered that the glow resistance of a starter on successive operation is quite variable and therefore the crest value of the transient is also not fixed at every measuring, but hase a range of voltage level variation.
It is well known that the wave form of the transient is whether aperiodic damped or oscillatory damped, depending on the magnitudes of the glow resistance and the parallel condenser capacitance.
The experimental results were obtained that the former is in case of the glow switch and the latter the thermal switch and the transient induced by the thermal switch is much larger than by the glow switch.

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