Been a bit anxious to know how you've been doing with this great project. Excellent news and progress Stefano! The Plasma Flame looks perfect and if it's quiet and tubes running as indicated, that is wonderful. Was that flame at 1KHz? Your makeshift cage also seems to be pretty effective. Are you still planning on running it horizontally into your horn? How are the ozone levels with this plasma size?
Small advice about raising the input voltage to max data sheet. Typically you would want to run it at about 80-90% to stay out of distortion range and not generating too many harmonics. A test at max is fine but running should be below.
A little confused by this...is the flame not completely silent now? What frequency are you running at now? Not sure a few MHz will make that much difference for all that work.- try higher mhz working frequency, different coils and cap (flame is fully silent)
Very happy for you and the progress you've made...a long way over a 18 pages and a years work!!
Till The next installment, ~PJ