By subjecting a tungsten core wire in the electro deposit solution containing {HEAD ~ the ternary carbonate} of 2.0 μm particles to cataphoresis, filament cathodes on each of which an oxide is coated in {TAIL ~ a thickness} of 0.5, 1, 2, 3, 4, 5, 6, 7, or 8 μm are fabricated 
By subjecting a tungsten core wire in the electro deposit solution containing { HEAD ~ the ternary carbonate } of 2.0 μm particles to cataphoresis , filament cathodes on each of which an oxide is coated in { TAIL ~ a thickness } of 0.5 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , or 8 μm are fabricated
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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