The ignitor is an OSRAM St 111 (4 thru 80w) fluorescent starter. It glows for 2 seconds until the Na10FL lights up. The spectrum of the Na10FL lamp at startup is that of mercury, thus the FL designation(?) (Need to record with my spectrograph to confirm if it's Hg). It quickly becomes overpowered by the sodium doublet..but the lamp remains feeble..the spectrum resembles the LPS spectrum but there is a faint continuum throughout which is bright at the violet-blue. That's the reason the lamp is enclosed inside a dichroic coated shield; the interference pattern created by the coating of the shield allows only the sodium doublet to pass.