Hi sorry I need to order soon I did some research and found that if the resistor is not on for more than 5 sec at a time the load can fluctuate a bit. I found 2 resistors one is 15kv and 4watts and one is 20kv and 2.5 watts. Is it better to one closer to the voltage or the wattage? Thanks.

 

R = V^2 / W
For 20kV to dissipate 2.5W the resistor would be 160MΩ so if the resistor is greater than or equal to that then the resistor will be OK.
for 15kV to dissipate 4W the resistor would be 56.25MΩ so if the resistor is greater than or equal to that then the resistor will be OK.

 

R = V^2 / W
For 20kV to dissipate 2.5W the resistor would be 160MΩ so if the resistor is greater than or equal to that then the resistor will be OK.
for 15kV to dissipate 4W the resistor would be 56.25MΩ so if the resistor is greater than or equal to that then the resistor will be OK.

Thanks I think I understand. The 20kV resistor I found is rated at 1000MΩ so I am guessing it will be OK running the 5W I am putting through it.
Hopefully it isn't overkill and will still spark.
http://uk.farnell.com/ohmite/sm108031007fe/resistor-20kv-1-gig-1/dp/1550788

 

i think not need to diod help at all..