{TAIL ~ Two electrodes} {HEAD ~ each} having an electrode tip at a mutual distance EA are arranged inside the discharge vessel 
{ TAIL ~ Two electrodes } { HEAD ~ each } having an electrode tip at a mutual distance EA are arranged inside the discharge vessel
TAIL TAIL TAIL TAIL TAIL TAIL HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH