In a preferred embodiment, {HEAD ~ a plurality} of woven wire mesh screens are stacked in {TAIL ~ layers} to form the radiation shield, with wires in adjacent layers being offset from one another such that the radiation shield is substantially opaque to infrared radiation while permitting the passage of the alkali metal vapor 
In a preferred embodiment , { HEAD ~ a plurality } of woven wire mesh screens are stacked in { TAIL ~ layers } to form the radiation shield , with wires in adjacent layers being offset from one another such that the radiation shield is substantially opaque to infrared radiation while permitting the passage of the alkali metal vapor
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH