I've already made all the stages and it was powerful enough to lit 18W fluorescent bulb, but I failed to make the plasma flame. I've burned so many MOSFETs, it was so exhausting,I was about to give up. And then I got idea. Why don't i reverse engineer a device I have. This way I could be sure where is the problem. Using the ideas and techniques I wrote on my previous post I made my own DIY output coil. Voila! It worked 

Few important things one can learn here. Device unloaded frequency and coil self frequency can differ even in one mega Hertz and it will be ok. 200KHz is what you see. Most interesting fact is that final output is not frequency where it's getting lower oscilloscope reading but where it gets higher. 

Just to make sure we are on the same page here, 200KHz equal to reducing one or two turns in 30mm diameter coil. Reducing the output wire by centimeter also increases the output frequency by 100KHz. Adding metallic discharge nut/bolt may reduce by 500KHz. Pulling the wire up will reduce frequency. 

As you see there is a lot of ways to change frequency of output coil, one thing certain once you fix the frequency make sure nothing moves.

Another thing is to add output termination otherwise copper wire will burn once power is high enough, be aware...

Now it's time for connecting all together, Oh la la, nothing is working! What happened? It looks like my main circuit is on 200Volt instead of 1KV! What why? Oh! I forgot I used some old MOSFETs from unknown source some of them are bad and vary greatly in specs. I don't believe I felt twice on same mistake. 

Bought another bunch of IRFP260N MOSFETs, fingers crossed!

Stay tuned! 😁