a multipulse starting aid for a high - intensity discharge lamp includes a spiral line , a bi - directional solid - state switch , or a spark gap , coupled to one of the ends of the spiral line , a resistance in association with the spiral line to provide an rc time constant . the time constant rc is so adjusted that , upon receiving the alternating current voltage from the appropriate source , a waveform of voltage is presented across the pair of terminals of the lamp , together with the series of pulses at the peak of each half cycle of the waveform . thereby enhancing the lamp startability .