WTD: electric field mill, maybe a Boltek

[Don Taylor]

Looking for an electric field mill, a little instrument that measures
the electric field in the air above it. Boltek makes these. Others
would be considered. Other field measurement instruments might do.

Also looking for a magenetometer/gaussmeter for long term geomagnetic
field measurements.

thanks

 

[Jim Adney]

On Fri, 10 Jun 2005 03:44:35 -0500 Don Taylor <dont@agora.rdrop.com>
wrote:

Looking for an electric field mill, a little instrument that measures
the electric field in the air above it. Boltek makes these. Others
would be considered. Other field measurement instruments might do.

Also known as generating voltmeters. They are used in electrostatic
particle accelerators to measure the DC terminal potential.

What kinds of fields/gradients are you looking at?

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Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
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[Don Taylor]

Jim Adney <jadney@vwtype3.org> writes:

On Fri, 10 Jun 2005 03:44:35 -0500 Don Taylor <dont@agora.rdrop.com> wrote:
Looking for an electric field mill, a little instrument that measures
the electric field in the air above it. Boltek makes these. Others
would be considered. Other field measurement instruments might do.

Also known as generating voltmeters. They are used in electrostatic
particle accelerators to measure the DC terminal potential.

What kinds of fields/gradients are you looking at?

The sort of stuff associated with weather, day to day and the
occasional thunderstorm, perhaps 100 to 1000 volts/meter.

There are a variety of web pages describing how you can try to
build one of these yourself. Scientific American, Amateur Scientist,
published one in 1999 I think and there are others out there.
(but with my mechanical skills I think that trying to build
something to spin one metal garbage can inside of another and
in close proximity and at 7000 rpm would earn me a spot on the
"World's Stupidest Person" television show somewhere)

I'm also looking for a magnetometer for geomagnetic field variation
measurement.

Anyone know of a source of either of these, perhaps used?

Thanks

 

[Fred McKenzie]

In article <lZadnR_DCoi4ETffRVn-2g@scnresearch.com>, dont@agora.rdrop.com wrote:

Jim Adney <jadney@vwtype3.org> writes:
What kinds of fields/gradients are you looking at?

The sort of stuff associated with weather, day to day and the
occasional thunderstorm, perhaps 100 to 1000 volts/meter.

I'm also looking for a magnetometer for geomagnetic field variation
measurement.

Anyone know of a source of either of these, perhaps used?

Don-

Because of the threat of damage to launch vehicles, field mills have been
used extensively for lightning research and prediction at the Kennedy
Space Center. If they didn't invent them, they probably improved them.

There is a chance you can find some old ones that were replaced or
upgraded. Check out http://surplus.ksc.nasa.gov/. They are responsible
for disposing of all kinds of scientific and industrial equipment that is
surplus to the Space Program.

If you can find reports published by some of the researchers, there may be
e-Mail addresses you can contact for more information. Someone working
there might be more aware of when equipment is to be replaced or
upgraded. If you are associated with a university research program, it
might be possible for them to transfer surplus property directly instead
of auctioning it off.

Fred

 

[Fred Abse]

On Fri, 10 Jun 2005 03:44:35 -0500, Don Taylor wrote:

Looking for an electric field mill, a little instrument that measures the
electric field in the air above it.

The space above it, actually. Air isn't needed.

Boltek makes these. Others would be

considered. Other field measurement instruments might do.

Take a look at New Mexico Tech Langmuir Lab website. Their EE department
build them. Plenty of detail, including circuits. They're not difficult to
make, if you have machining facilities (or even if you don't, and don't
mind a bit of crudity). Calibration is a breeze.

One day, I shall do one. Probably after the Schumann resonance antenna

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)

 

[Jim Adney]

On Sat, 11 Jun 2005 02:00:53 -0500 Don Taylor <dont@agora.rdrop.com>
wrote:

Jim Adney <jadney@vwtype3.org> writes:

What kinds of fields/gradients are you looking at?

The sort of stuff associated with weather, day to day and the
occasional thunderstorm, perhaps 100 to 1000 volts/meter.

Okay, that's a lot lower field than one sees in particle accelerators,
so you'd need larger rotors and/or faster rotors.

There are a variety of web pages describing how you can try to
build one of these yourself. Scientific American, Amateur Scientist,
published one in 1999 I think and there are others out there.
(but with my mechanical skills I think that trying to build
something to spin one metal garbage can inside of another and
in close proximity and at 7000 rpm would earn me a spot on the
"World's Stupidest Person" television show somewhere)

;-)

Okay, I see your problem. The ones we used were only about 2-6"
diameter and ran at 1800 or 3600 rpm, but this was for fields somewhat
above 1MV/m.

-
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Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
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