On one side of Thor's top toroid a stainless steel sphere has been mounted (diameter 25 mm) in order to provide a preferred spot for the discharges. The target is made with a vertical aluminum pipe, which has its top end bended horizontally for about 200 mm. The pipe is mounted on a pedestal and grounded. An insulator is mounted on the pipe bended end and a 60 mm diameter copper ball terminates the target. The resulting copper ball height from ground is the same than Thor's stainless steel little ball.
A thick shielded cable runs inside of the aluminum pipe. Its central conductor is connected to the copper ball and its shield is connected to ground at the pipe bottom. The central conductor runs through a Pearson current probe and is then connected to ground. The Pearson probe (mod. 110A, 20 MHz, 0.1 V/A) is located inside a grounded steel box and connected to a digital storage scope by a shielded cable, grounded at both ends.
The toroid voltage is measured by my liquid resistive divider providing a dividing ratio of 135400:1.
