On Jun 24, 2007, at 3:50 PM, Michel Jullian wrote:
I had some trouble coming to terms with this observation myself
when I first experimented with corona discharges, but emitter
current is equal to plate current at all times, not just on
average, even though the ions take ages (milliseconds) to cross the
gap. Try it if you don't believe me.
But we may not have corona discharges here.
A more experienced friend gave me the answer to this apparent
paradox: the plate charge is equal and opposite to the sum of the
charges on the emitter and in the air.
False. This is true only on average for drops. This is assuming
steady state current flow, which drops do not provide. They impart
an AC signal and that signal couples in part directly to ground, and
thus puts the emitter AC signal through R4 in that circuit loop.
When the drops arrive, more of their charge is induced on the plates
(vs direct to ground), and that puts an AC signal on the plate and
thus through the R1 or R3 loops. If the drops have exploded in the
process then the AC signal on the plates would be diminished.
In terms of circuit theory, as far as the ground connection is
concerned, the PS + T1 + discharge device is a dead end (open
circuit), so no current flows through it (the whole thing could be
disconnected from ground and would still operate identically), it
just sets a voltage reference. So if you apply KCL http://
en.wikipedia.org/wiki/Kirchhoff%27s_circuit_laws the current in R2
is equal to the current in R1 (at all times).
OK, so it appears you want to utterly dismiss the possibility of
drops or filaments, and the effect of the coupling of an AC signal to
other paths through ground, or through a conducting filament. You
seem to want to consider only DC steady state. Within those confines
a ring-pass-through set-up should still be interesting. Bill did say
he had successfully done that.
---------------
| |
Emitter V |
. |
|
. |
|
Ring O . O |
| o-----C1----o AC Signal (Optional)
. | |
| |
Plates ___ ___ | T1=== AC
| | | |
| | R4 |
| V3 o | P
| | | |
| R3 | |
| | | |
-o-R1-o--G---R2-o-
| | |
o o o
V1 G V2
Fig. 2 - Circuit diagram for ring pass-through drop/thread
detection
Fig. 2 is again a diagram of the ring pass through concept. It shows
that there is at least one alternate current path through the ring
and thus R4 to ground. This takes fixed font Courier to view.
In the case of ions, at some ratio of distances, but still
maintaining the stream through the ring to the plates as Bill did, I
would expect a significant amount of the ions go to the ring and not
to the plates (but not so for a true conductive filament). From a
corona R4 would take a significant proportion of the current R1+R3+R4
= R2. Further, of those charges that make it to the plates, I would
not expect a sharp change in current from R3 to R1 as the emitter and
ring are passed from left to right over the plates, but would for a
filament.
Regards,
Horace Heffner
