In article , Ed Huntress
wrote:

On Fri, 24 Oct 2014 13:33:50 -0700 (PDT), wrote:

On Friday, October 24, 2014 11:26:51 AM UTC-4, Ed Huntress wrote:
On Fri, 24 Oct 2014 07:55:45 -0700 (PDT),
wrote:

On Friday, October 24, 2014 8:15:52 AM UTC-4, Ed Huntress wrote:
On Fri, 24 Oct 2014 04:42:29 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Martin Eastburn fired this volley in
:

That is 1000 times if those are the correct values of 10^11 vs 10^14.
That is a wide band difference.


It doesn't much matter how wide the difference is.

Lacking a tuned tank, any arc (AC or DC or HF modulated) is a
"broadband
emitter", radiating RF all the way from SLF (audio) frequencies clear
up
to ultra-short wavelength UV. (and maybe beyond).

Some welders have chokes and various tank circuits (generally in the
form
of low-pass filters) to help prevent emission through the body of the
unit, but the welding leads always act as antennae.

Of course, any electrical apparatus has "tuning peaks" that tend to
absorb or radiate certain frequencies preferentially over others.
Manufacturers try to make their units suppress radiation in the ranges
where radio communications is done -- with varying degrees of success.


It's generally recommended that people with electrical cardiac or
neurological assistance devices avoid close proximity to arc welders
of
any kind.

Lloyd

Lloyd, the radiation from welding arcs is nowhere near "broadband."

Which welding arc? When welding which material, substance or element?
Different types of energy are emitted per materials used. Arcs form
inside microwave ovens (due to conductivity, etc)

Wel

If you have evidence of welding arcs producing significant microwave
radiation, please let us know.

Gee, I'd have never thought you'd get all "college boy" on us, Ed. Here
goes:
"The microwave emission from a plasma in a magnetic field is calculated
theoretically using Kirchhoff's radiation law for cases when characteristic
waves do not couple within the plasma. "
-- http://journals.aps.org/pr/abstract/...ysRev.122.719\

The paper, "Incoherent Microwave Radiation from a Plasma in a Magnetic
Field," is primarily about plasmas in waveguides. But you could derive
the output of a welding machine from the equations, and you apparently
have, since you've cited the paper as evidence that welding produces a
lot of microwave energy. As you put it, "...remember, the act of
welding is emitting microwaves. So you are cooking yourself while you
are welding."

So, you must have worked it out. What did you come up with? Does it
agree with the spectral graph that the American Welding Society and
others have determined experimentally? If not, why not?

Here's that graph, as a reminder. Scroll about halfway down the page:

http://www.ehime-iinet.or.jp/ehime_e...bun/ronbun.htm

Let us know what they got wrong.


"A welding arc is a plasma maintained between oppositely charged electrodes. "
-- http://ntrs.nasa.gov/archive/nasa/ca...0040139717.pdf

Yes it is. Now what?


Something is being missed here. There are three kinds of radiation
from an arc welder:

1. Thermal (black-body) optical radiation, simply because the metal is
white hot.

2. Optical line radiation due to electrically ionized atoms.

3. Radio-frequency radiation due to electrical resonances in the
welding circuit. http://en.wikipedia.org/wiki/Arc_converter


UV comes from 1 and 2, while open-air microwave cooking comes from 3.


Joe Gwinn