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Re: Thermionic emission, was Nylon nuts and bolts
Original poster: "" <tesla@xxxxxxxxxxxxxx>
Well, Scott is a very knowledgable person and he may be right in correcting me,
probably is. Here is a simple google explanation:
thermionic emission (thûrm'īŏn`ĭk), emission of electrons
electron, elementary particle carrying a unit charge of negative electricity.
Ordinary electric current is the flow of electrons through a wire conductor
(see electricity ). The electron is one of the basic constituents of matter. An
atom consists of a small, dense, positively charged nucleus surrounded by
electrons that whirl about it in orbits, forming a cloud of charge.
..... Click the link for more information. or ions ion, atom or group of atoms
having a net electric charge . Positive and Negative Electric Charges
A neutral atom or group of atoms becomes an ion
by gaining or losing one or more
electrons or protons. Since the electron and
proton have equal but opposite unit
charges, the charge of an ion is always expressed as a whole number of unit
charges and is either positive or negative.
..... Click the link for more information. by substances that are highly
heated, the charged particles being called thermions. The number of thermions
emitted increases rapidly as the temperature of the substance rises. The heated
material may be in the form of a metal filament or of some compound that coats
and is heated by the filament. If the heated body carries a positive or
negative charge, the thermions will be of the same charge. At temperatures
below red heat (see black body black body, in physics, an ideal black substance
that absorbs all and reflects none of the radiant energy falling on it.
Lampblack, or powdered carbon, which reflects less than 2% of the radiation
falling on it, approximates an ideal black body. Since a black body is a
perfect absorber of radiant energy, by the laws of thermodynamics it must also
be a perfect emitter of radiation.
..... Click the link for more information. ),
thermionic emission from uncharged
bodies is chiefly positive; at higher temperatures it is negative. The effect
was discovered by Thomas A. Edison in 1883 when he was working on filaments for
the electric light. Thermionic emission's most important practical application
in electronics is in the electron tube electron tube, device consisting of a
sealed enclosure in which electrons flow between electrodes separated either by
a vacuum (in a vacuum tube) or by an ionized gas at low pressure (in a gas
tube). The two principal electrodes of an electron tube are the cathode and the
anode or plate.
..... Click the link for more information. , since it is the mechanism by which
electrons are emitted from the cathode.
Quoting Tesla list <tesla@xxxxxxxxxx>:
> Original poster: "Scott Hanson" <huil888@xxxxxxxxxxxx>
> Possibly some misunderstanding here .......thermionic emission has
> nothing to do with "heat shedding".
> Perhaps you are thinking of the "emissivity" of a surface?
> Thermionic emission is thermally-induced emission of electrons, the
> most familiar usage being in the cathode of vacuum tubes of various
> types (CRTs, magnetrons, diodes/triodes/tetrodes/pentodes, etc). The
> heated cathode is the internal source of electrons that enables a
> flow of current through the tube, or in the case of CRTs the creation
> of an electron beam to "write" on the phosphor-coated screen and
> create a visible image.
> In thoriated tungsten TIG welding electrodes, the thorium oxide is a
> source of alpha particles, which helps generate consistent
> arc-starting characteristics and helps stabilize the arc once
> started. Again, nothing to do with heat shedding.
> Scott Hanson
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Tuesday, July 18, 2006 3:23 PM
> Subject: Re: Nylon nuts and bolts
> >Original poster: "" <tesla@xxxxxxxxxxxxxx>>
> ....sort of like using 2% Thoriated Tungsten for the rotary spark gap. I
> know that the thoria increases the thermionic
> >emissions (heat shedding) but if that bad boy is spinning at around 3600
> >rpm, it's cooling itself!
> >John F. Cooper III