HFSSTC-Increase Current in primary/Reducing Switching Loss

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Joaquin Valdez 1

Joined Apr 11, 2018
7
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Hello, I have been build this high frequency solid state tesla coil for a while now and have tried quite a few different circuit with some success but ultimately I have fry a lot mosfets in the process, so far this is best I have came up with but I have a few problems.

1. Alot of these hfsstc that I have seen have a very hot orange arc and act more like a flame then the traditional blue/purple long arcs of a normal tesla coil its some time just called a (Plasma flame) there is not a lot of info about why the arc is like this all I could find is that its a combination of a high frequency general above 4Mhz, power density of the arc, Low amount of secondary windings, but the output of my circuit produces the flame like arc but it is still blue/purple color I suspect if I could increase current in the primary I could get the arc to change into that orange color. I have tried to reduce L2 but this did not change the color of my arc but increased the amount of heat produced by the IRFP460.

2. I had hopes of trying to make this design portable and I wanted the circuit to be as efficient as possible hence the use of a slayer exciter like input, but I don't use these kinds of rf circuit often and wanted to know if there are any methods I could use to reduce switch loss in mosfets .

3. When testing the circuit on a breadboard I notice if I added decoupling capacitor(a few 470n film caps) the circuit would not start up my guess is that instability in the power rail is what gets the circuit started but how could I modify this so the circuit starts up reliably.

4. Most the circuits I could find exploit a mosfets gate capacitance to oscillate I have had some success with this circuit but tuning takes forever, I dont get a great output, it produces a lot of heat, and it absolute destroys mosfets but is their any difference between my and these self oscillating circuit which could be affecting my arc color. vvvvvvvvvvv
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AlbertHall

Joined Jun 4, 2014
9,882
Both the MOSFETs in the top diagram are shown with drain and source swapped. They are both N channel and have the drain connected to ground and the source powered from a positive voltage.
 
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