{HEAD ~ magnetic screens} with magnetic means provide {TAIL ~ a magnetic field} that has a minimum value, close to zero, at an anode area, in such away that a magnetic field increases along a discharge channel and at a distance of about ½ of a discharge channels length its maximum values of magnetic field become Br≧0.6 Br,max 
provide
{ HEAD ~ magnetic screens } with magnetic means provide { TAIL ~ a magnetic field } that has a minimum value , close to zero , at an anode area , in such away that a magnetic field increases along a discharge channel and at a distance of about ½ of a discharge channels length its maximum values of magnetic field become Br≧0.6 Br , max
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH