Re: SSTC theory

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Antonio,

On 25 Jun 2004, at 20:32, Tesla list wrote:

 > Original poster: "Antonio Carlos M. de Queiroz" <acmdq-at-uol-dot-com.br>
 >
 > Tesla list wrote:
 >  >
 >  > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 >
 >  > I don't think I was ever convinced that streamer loading was a >
 >  culprit. The typical operation mode is to ring the secondary up until
 >  > it lets go and one usually designs the secondary to not let go
 >  until > the bulk of primary energy has reached it (at which point
 >  there is > little left in the primary to transfer). In my opinion,
 >  recent > attempts to use matching theory are valid only if one wants
 >  to feed a > continuous arc in CW operation. I seriously doubt its
 >  validity when > applied to either classic disruptive coils or the
 >  ISSTC which is > pretty much the same thing when examining the
 >  operation of the > secondary in such coils. Past experience with my
 >  disruptive coils > often (if not always) showed better results with
 >  the primary tuned to > what would have been the LSB generated with
 >  the tunings equal. This > was referred to in the past as "offset
 >  tuning" and has appeared in > early papers on TCs. I forget which
 >  ones but I have seen voltage vs > tuning graphs in some of them. I
 >  still have those papers buried in a > mountain at home.
 >
 > Really, considering that:
 > 1) The load is seriously nonlinear, and only effectively appears after
 > breakout. 2) Most systems are not operated continuously, but in short
 > bursts, maybe just short enough to build up enough energy in the
 > secondary system for breakout. Something that shall be looked in the
 > design is then what happens while the output voltage is rising, in a
 > condition of, ideally, no load. The ideal would be to always present a
 > resistive impedance to the driver while in this condition. But this is
 > precisely what happens if the load is removed from the "matching
 > theory" design. The input current is always in phase with the input
 > voltage while the output voltage is rising. If the energy is not
 > spent, after some cycles, the output voltage reaches a maximum (of
 > about two times the designed output voltage) and starts to fall. While
 > it is falling the input current is in opposite phase to the input
 > voltage, returning energy to the power supply. I will see if I can
 > work out the details of the curious waveforms that appear, and see if
 > they are naturally in this way, or are forced to this way by the
 > matched design, that appears to work well in this aspect too.
 >
 > Antonio Carlos M. de Queiroz

I think matching to the base of an unloaded resonator is a most
fruitful approach in a number of respects:

- noting that a capacitor that is running down in a traditional
disruptive system still continues to pump the secondary until it is
empty (given ideal k for this to happen), I see no reason why a drive
system operating in what is effectively CW mode should ever suffer
the phase reversal inherent in the traditional endpoint of energy
transfer.
- the way appears to be open for machines to be built to generate
enormous voltages in the MV range with very high storage energies to
boot with a rather modest drive system (Greg?)
- the ISSTC is a system where shooting for a *high* secondary Q
really comes into its own.
- by carefully shaping a breakout point, one can tailor a given
secondary to let go before it destroys itself. In fact one can
progressively shape it to restrain further and further as confidence
rises. A bit like opening up the gap in fact.

I expect the matching to be not-too-critical given the self-adjusting
drive frequency together with the transformation of MOhms to a few
tens of Ohms by Zo^2.

Again, none of this is really that new. Sloan's CW system worked in
much the same way.

Malcolm