A light source 14 wherein said helical portion turns through {TAIL ~ an angle} of {HEAD ~ at least about 720°} 
A light source 14 wherein said helical portion turns through { TAIL ~ an angle } of { HEAD ~ at least about 720 ° }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD