I know way too much about the propagation of plasma in fluorescent lighting. When you first hit a fluorescent tube with high voltage you need some cosmic radiation to rip off the first barium ion off the cathode which causes a tiny little lightning strike of plasma that skitters across the inner surface of the tube. Once it makes its way across the length of the tube to the anode you now have a conductive path. This path then grows tremendously until it envelopes the whole cross section starting from the anode and works it’s way back to the cathode until the whole tube is filled with wonderful plasma that makes light when it excites the phosphor coating.