On Fri, 05 Sep 2008 15:41:15 -0400, Jon Mcleod
wrote:
The novocure dude is talking about 2 V/cm, and the prof here is talking
about 1V/cm. I don't need to duplicate this experiment, I need to
immerse a T-Bone into a 1V/cm, 100kHz e-field. I appreciate your help
so much, but I don't understand where 550,000V/m is coming from???

Hi Jon,

Take 550V (the average of their amplifier's 300-800V capacity) and
place it across 1mm. How many volts per meter?

Consider the claim and specification of 1V/cm. How many volts per
meter?

How many volts will you need to obtain 1V/cm across a T-Bone steak
measuring 20 centimeters?

If you can solve one, you can solve them all.

Where did the missing voltage go? This is a simple series impedance
relationship that is linear with distance. To obtain 1V/cm from the
author's source demands that there is considerable impedance isolating
the sample from the excitation probes. This could be accomplished if
there were a huge air gap between the first excitation probe and the
cells' culture, and perhaps a corresponding huge air gap on the other
side of the cell culture towards the second excitation probe. The
ratio of impedances would be 550,000/10. The sum of both air gaps'
impedance would have to exceed the cell culture's impedance by this
ratio.

This is possible, but the report is obscure to that possibility. The
introduction of field measurement probes would be exceedingly
disturbing to the balance of impedances too. The diameters of those
probes consume half the gap within which the cell culture resides, and
lay in exceedingly close proximity to the excitation probes! The
probes themselves present more mass and area than the cell culture.

The claims are specific, but all the evidence points to the authors
having convinced themselves of a very problematic measurement. They
are, afterall, no more versed in the art of antenna math and finite
element modeling than you are. They got numbers to be sure, and
performed what every student would recognize as "plug-n-chug."

However, you are more interested in the results than the claims. Your
assignment, as I understand it, is to investigate what results follow
from your own variation of their work. Unless you are trying to also
validate the correlations to fields, which I seriously doubt you could
do, and would be suspect through direct attachment (as it does not
conform to the original); then I would suggest you think smaller gap
(not a T-Bone), up the voltage (as offered), and measure bacterial
activity.

Or, in your own terms:
What I ACTUALLY NEED to do is generate a 100kHz electric field, at
1v/cm, across a T-Bone steak, to measure whether it retards or
accelerates decomposition over time. The hypothesis is that the e-field
retards growth of certain bacteria inside the meat.
Set your function generator for a 1 volt output, separate two probes
by 1 centimeter, place 0.99 centimeters of steak between. I will hope
your grade isn't scored in competition to others puting their effort
into more voltage across smaller gaps.

73's
Richard Clark, KB7QHC