The recommended components you should get are ceramic capacitors and 1M 1 watt resistors. The ceramic capacitors are best suited for this project, because they are cheap, readily available, and they are good for in pulse discharge circuits. Polypropylene pulse-rated capacitor would also work well, but are more expensive, and harder to find with high voltage ratings. The resistors should be about 1M and 1 watt type, the normal 1/4 watt resistors are very unsuitable, if used, it will cause arcing and the resistors will burn out and damage the marx generator, so use the 1 watt metal glazed or carbon film resistors is suitable.
If in doubt, try building just a couple of stages first to see how well the parts you use will work before you buy more...
But I will tell you what I used...
- Ten 1nF, 4Kv ceramic capacitors
- Twenty 1M, 2 watt, 500v carbon film resistors (I brought the 2 watt resistors because they are somewhat cheaper then the 1 watt resistors!)
- Two 4.7M, 1 watt, 3.5Kv metal glazed resistor for the Rb.
You can use capacitors with larger values to get fatter, louder sparks, but take longer to recharge! You can often run capacitors in excess of their rated voltage, but obviously this increased the risk of failure!
And don't forget, the size of sparks at the output gap will depend on the input voltage and number of stages...
I got all my components from Farnell. Here is a list of things you will need to get if you are going to buy the components from Farnell.
1nF 4Kv ceramic capacitors
1M 2 watt 500v carbon film resistors
4.7M 1 watt 3.5Kv metal glazed resistor