Hi guys, this is my first post here. I hope I'm in the right section.
I've made a slayer exciter with a 22kohm resistor, a 2n2222 transistor, using a 9v battery. My secondary is 0.25 mm and 10 cm in lenght. My primary is 4 turns.
I wanted to obtain some sparks, and I added a 47k instead of 22k. And a pair of 2n2222. I'm planning to use 2 9v if this will work.
Here is a pic of my circuit.

And another one:

If you have any suggestion, please let me know thanks!

 

You are making the same mistake many doing this do, randomly wiring things together, using long jumper wires between the parts. All of those long jumper wires have an effect on the circuit. Many other people come here asking the same type question on the same circuit, most of them using bread boards with long wire between the components. The circuit was developed using those components closely connected, when you add long wires it throws the circuit parameters off. Random length wires have capacitance and inductance to them, that wasn't in the original circuit.

 

Put it on veroboard, shorter leads and use a better battery, like Nicads or Lithiumi-on

 

I am not sure but it looks like you have the base winding connected backwards. The collector should connect to the coil with few windings. Also cannot tell from the photo but it looks like you may have the emitters swapped with the collectors or you do not have a Darlington. Can you show us or point us to the schematic you were following?

 

Where is the diode??? This is a typical Slayer Ckt using a LED for the diode. It is difficult with a battery and the battery must be fresh and fully charged to work. At best you will get a tiny blue corona at the tip of the secondary coil.