Source - Gordon England
A plasma is an electrically conductive gas containing charged particles. When atoms of a gas are excited to high energy levels, the atoms loose hold of some of their electrons and become ionised producing a plasma containing electrically charged particles - ions and electrons.


The plasma generated for plasma spraying usually incorporates one or a mixture of the following gases:

Argon
Helium
Nitrogen
Hydrogen

Plasma flames for thermal spraying can produce temperatures around 7,000 to 20,000K far above the melting temperature (and vapour temperature) of any known material. The extreme temperature of the plasma is not the only reason for the effective heating properties. If for example helium gas is heated to around 13,000K without a plasma forming, it would have insufficient energy for normal plasma spraying. Nitrogen on the other hand heated to 10,000K going through dissociation and ionisation forming a plasma is an effective heating media for thermal spraying, being able to supply about six times more energy than an equal volume of helium at 13,000K. The plasma is able to supply large amounts of energy due to the energy changes associated with dissociating molecular gases to atomic gases and ionisation which occur with little change in temperature.


N2 + E = 2N
Diatomic molecule of nitrogen + energy gives 2 free atoms of nitrogen
2N + E = 2N+ + 2e-
2 free atoms of nitrogen + energy gives 2 nitrogen ions and 2 electrons

The reverse process provides most of the energy for heating the spray material without a dramatic drop in temperature:


2N+ + 2e- = 2N + E
2N = N2 + E

Nitrogen and hydrogen are diatomic gases (two atoms to every molecule). These plasmas have higher energy contents for a given temperature than the atomic gases of argon and helium because of the energy associated with dissociation of molecules.


Argon and Helium are monatomic gases (the atoms don't combine to form molecules) These plasmas are relatively lower in energy content and higher in temperature than the plasmas from diatomic gases.


Nitrogen is a general purpose primary gas used alone or with hydrogen secondary gas.

Nitrogen also benefits from being the cheapest plasma gas. Nitrogen tends to be inert to most spray material except materials like titanium.


Argon is probably the most favoured primary plasma gas and is usually used with a secondary plasma gas (hydrogen, helium and nitrogen) to increase its energy. Argon is the easiest of these gases to form a plasma and tends to be less aggressive towards electrode and nozzle hardware. Most plasmas are started up using pure argon. Argon is a noble gas and is completely inert to all spray materials.


Hydrogen is mainly used as a secondary gas, it dramatically effects heat transfer properties and acts as anti-oxidant. Small amounts of hydrogen added to the other plasma gases dramatically alters the plasma characteristics and energy levels and is thus used as one control for setting plasma voltage and energy.

Originally posted by Red Golem
Mad Man
YOu said the air force has gone public that they have been interested in an anti matter bomb. Do you have the link or any more info on this?

Originally posted by ben91069
Jesus Christ, NetStorm. I am extremely disturbed by that article. Primarily, it says nothing of the potential for this technology other than a gigantic killing device. They say spending billions to corral this antimatter so they can build a bomb? WTF? Is this really what the best minds in politics and science have to offer is a wonderful, clinical method of killing a city without nuclear fallout? By god I hope they blow themselves up and let society take care of itself. I hope these particle accelerators are located right beneath DC and they screw up and destroy themselves. I just want a light bulb that will last more than 1000 hours.

Originally posted by ben91069
Although I know the civil benefits of this would be realized eventually, I cannot believe that it isn't being developed first for the military. The A-bomb was built first before they ever built a reactor, wasn't it.......

Originally posted by sardion2000
No I do not think so. I seem to remember a polish or german husband and wife team who were the ones to dicover fission in a crude reactor without any shielding. Suffice it to say they both died a short time later.

Another problem is the means by which one might contain the antimatter and then capture the energy once it reacts with matter. Containing antimatter is no small feat since it must be stored in something which is not made of matter. Currently electric and magnetic fields are used, though it is not clear how one would use this sort of containment device on any more than a few atoms or particles.

Originally posted by ben91069
This anti-matter thing has got me thinking. I am just smart enough to build houses and fix cars, but I am no physicist. I heard a theory about electricity not actually being generated in a conventional sense by generators, but the actual energy comes from the aether or I guess from the empty space that we cannot account for. In other words, the electro-mechanical action of producing current flow in a wire is half the phenomenon - the actual energy comes from the aether and the physcial current flow is the observable part of this. Is this, if anyone knows, connected to anti-matter?