Best place to start is with the Wiki. Lab-Tesla authenticated the graphics shown on this page.
https://en.wikipedia.org/wiki/Teleforce
In the above diagram the figure on the left shows a modified Van de Graaff generator. Normally the Van de Graaff generator uses a rubber belt to transfer a positive charge to the top of the tower where it accumulates. The process exploits the triboelectric effect. In the Tesla particle beam weapon a high voltage DC power supply is used to spray the positive charge into a stream of dry gas at callout 12, and the negative terminal is connected to callout 13. This dry gas is conducted through a loop of hollow ceramic insulators connected together with air tight seals. The gas loop is powered by the Tesla pump, driven by the Tesla turbine shown in callout 5.