WOW AM I CONFUSED NOW.  We have a small coil 5"x22 powered by a 15kv 60ma 
NST.  using 0.012uf cap.  Our current spark gap is 18 sections of cu pipe 
with a total gap of 0.300"  this gives us nice 4 foots streamers off a 16" 
corona ball.  Well we never are satisfied with what we have so had to try 
something new.  replaced the spark gap with a hydrogen thyratron, thinking it 
would be quieter and improve the Q so all would be better.  Well .... the 
thyratron would not hold off the voltage as expected and freely anode fired 
without any trigger applied. Used a thyratron rated for 16kv and only had 
input powerstat at about 3kv.   but that is not the question.. the question 
is why did the coil get big arcs up and down the secondary while the tube was 
anode firing?????
any ideas would be greatly accepted..
Phred and Inspector Mike