another thought on symmetry and fillament formation. limiting the places that fillament formation can take place can lead to stronger and well placed fillaments. along with formation, supplying a rail for fillament travel could help in keeping a fillament attatched to the cathode before rundown.
one or two points to start a fillament using a small flyback transformer supplementary circuit to ensure a well formed streamer and then hit it with the big hammer cap bank………….symmetry.
