I had fun with plasmas in the air a few years ago. I had made a simple LC circuit with an end plate. Near the plate, I injected current into the air from a tip connected to a very high voltage DC source.
The system oscillated, the oscillation could be produced up to a frequency of about 2MHz, with a voltage > 10 KV, which could then be lowered to about 8 KV once the oscillation was triggered. It is clear that there was a negative resistance in the plasma, this is known, but as in all cases when this happens, it is a dynamic resistance (so no hope of OU, you have to polarize it, therefore to provide energy).
Here the high voltage is AC. AC can also ionize the air on the hot side of the resonant circuit if the voltage is sufficient. There is no longer a fixed current to maintain the bias around which the dynamic resistance is negative. The resistance of the circuit will depend on the applied voltage, but we will probably have the negative resistance still appearing fleetingly when the AC voltage is around that point. If the AC is at low frequency, a few tens to hundreds of KHz, oscillations at higher frequencies or distortions of the signal may therefore occur for short times around the point of negative resistance at each period of the AC
It becomes very difficult to characterize the input and output powers without tools in the RF domain capable to measure arbitrary signals. An oscilloscope with math functions would be the solution, but because of the strong ambient field, it is necessary to know how to connect it without magnetic or capacitive inductions polluting the signal of the probe, using for example double screened coaxial cables instead of probes, shielded connections... which is not within the reach of the first person, without RF experience. Don Smith had neither the technical means nor the skills to do this. For those who would like to test the system, and thus be able to make correct measurements, I can only agree with Vidura: "Better would be a DC input measurement with appropriate filters", and output too!
If the voltage is not sufficient to obtain an ionization, then we do not really see why the elementary setups seen above would produce anything abnormal that the engineers who have been using them for decades, would not have seen.
---------------------------
"Open your mind, but not like a trash bin"
|