Spherical topload SGTC

vasil, Tue Dec 22 2009, 04:51PM

OK, I have a few more no duty days (Chrismas time...), so I finished this project. It is a spherical topload SGTC (nothing special), but designed to obtain spontaneously the "swirling streamer effect".

The whole system is here:



It has a 800 turns, 36 cm secondary, on 11 cm diameter PVC pipe and a big sphere covered with alu foil, big enough to overload the system to achieve the max potential before spark formation.

The tank is here:



A few details:

-20 nF @ 20 kV MMC



- two 7 kV @ 25 mA little NSTs in parallel, for 7 kV @ 50 mA



-a safety gap with two 470 pF @ 30 kV doorknobs as filter caps:



-a multiple gap with a 40 W air fan. It needs a screw and a spring to be added later for fine variation of the gaps distance, but I didn't have the patience to finish it:



-the primary (taped at 5-th turn) and a cable switch, very good when taking pics/movies:



The result is here:

MOVIE 1

For the same settings of the SGTC (power input, gap distance, coupling, etc) we can influience the streamer formation just using different diameters spherical toploads. The method is using a smaller diameter sphere not connected with the main topload sphere, in a manner identical with the additional sphere on the electrodes of the electrostatic machines, to influience the spark formation. The idea is schematized here:



-the smaller sphere not connected to the main sphere, on an insulator cilinder:



The swirling streamer formation (unfortunately I can not get it permanently):

MOVIE 2

The project needs only fine adjustements.

Now I can finaly focus on the GMI90 VTTC project.