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Re: 50%
Tesla List wrote:
> From: "Fred W. Bach, TRIUMF Operations" <music-at-triumf.ca>
> >From hullr-at-whitlock-dot-comMon Oct 28 21:48:14 1996
> >In theory, We should never be more than 50% efficient in energy transfer
> >from one capacitor to another! i.e. the Cprimary to the Csecondary
> >Usually the resonator load capacitance plus Ion cloud loading. This
> >assumes 100% coupling and zero other losses! If fact, we are much lower
> >than that with the finest system in operation.
> >
> >50% of the capacitively stored energy always disappears in circuit loses
> >(resistive and magnetic) even with direct wired connections. There is a
> >lot of additional wasteful garbage going on in between the primary and
> >secondary capacitors.
> >
> >Richard Hull, TCBOR
>
> What are you talikng about? Some specific circuit I presume. Your
> post lacks quoted text and the second paragraph is rather general,
> so I take some exception.
>
> For instance,
>
> If I take a 0.1ufd cap charged at 10KV and another identical one
> but uncharged, and I connect them together (as you said, "direct
> wired connections"), even with a small resisitor in series, I will
> get a final voltage of very close to 5kV, will I not? This is
> nearly 50% of the energy in the first capacitor transferred to the
> second with very little losses to the circuit.
<snip>
Actually, No. Richard is correct, insofar as 50% of the capacitively
stored energy always disappears in circuit losses (resistive and magnetic)
when _direct_wired_connections_ are used to connect the second capacitor.
The cap charged to 5kV in the above example holds only _25%_ of the initial
energy, not 50% (CV squared and and all that).
However, the 50% efficency value is by no means an upper limit, if one is
allowed to use components other than direct wires. A switch in series with
an inductor between the two caps will do the job quite nicely:
When the switch is closed the current starts at zero, peaks at V/ SQRT(L/C),
then returns to zero in a nice smooth haversine. When the current crosses
zero the second time open the switch, and Voila! Perfect energy transfer!
I guess that the message here is "Never say never."
-GL