From: "Malcolm Watts"
Date: Mon, 18 Jun 2001 09:04:30 +1200
Subject: [TSSP] Some Considerations
Hello Paul, all,
I pondered your note on where we are at and what
needs to be done and have considered two points.
#1 - Top Volt msmt. The real ugly sister. There seems to be two
possible routes, both of which can be verified as to their
disturbance of the resonator. It is clear that any msmt must be
"central" to the resonator axis to avoid distorting the electric
fields around it.
(a) A probe running up through the centre. This might consist of a
*very* high resistance with a division resistor at the base to ground
(bottom end of the coil). It would probably have to be shielded with
a thick layer of insulation around the shield and compensated for
inherent shunt capacitance.
(b) A similar probe running vertically from the top of the coil with
instrumentation above it or an electrically isolated feed from its
top.
Both of these may be checked for disturbance by F and Q msmts before
and after. I don't see why doing such checks at low levels would be a
problem as long as there is no corona n the probe at normal running
voltages.
#2 - Top voltage vs breakout. We are all well aware that in normal
repetitive running of a TC there is little correspondence between top
voltage and streamer length. Therefore, any such relationship would
have to be done in single shot mode to a grounded point in my
opinion. FWIW, this is how I usually gauge the performance of a
resonator and/or system before proper firing. This *must* be done
while monitoring e-fields on the scope as more than a single transfer
implies additional power lost in the primary so the effectiveness can
be gauged by discounting discharges which result in multiple beats.
This should prove reliable as an indicator of normal running voltage
since we know that the low duty cycle of a repetitive TC does not
allow "bangs" to build on one another.
I welcome comment and discussion on all of these points. We simply
have to find a way of performing these measurements.
Regards,
malcolm
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.