Toroid thruster design close up. This shape has the advantage of reducing electric field distortions at corners by utilising a toroid shape for the collector. The wire is fixed above the toroid supported at 8 positions. The toroid shape was formed by a modelling balloon with aluminium foil strips wound upon the surface. Thruster weight is 10g, payload is 11g. Radius is 16cm, balloon length 1m, balloon cross sectional diameter approx. 3cm. Wire to toroid upper surface distance = 5.5cm, Voltage = 55kV, Current = 0.7mA
In another version, the balloon was sprayed with graphite spray instead of aluminium foil, and this drastically reduced the device weight from 10g to less than 2g, with the same payload capacity, resulting in the best payload to thruster weight (>x4) ever achieved!.