The discussion revolves around the nature of fields exerted by argon plasma, particularly focusing on whether these fields are electric or magnetic, and their potential effects on electric machinery placed within the plasma. Participants explore various scenarios involving the interaction of solid objects with argon plasma, including the implications of charging, etching, and potential damage to machinery.
Participants express differing views on the nature of fields in argon plasma and the potential for damage to machinery, indicating that multiple competing perspectives exist. The discussion on achieving specific pressures in plasma remains unresolved, with no consensus on the feasibility of reaching 1000 psi.
Limitations include assumptions about the ionization state of the plasma, the complexity of calculating pressures and densities, and the dependence on specific experimental conditions that are not fully defined.
Khashishi said:A solid object immersed in a plasma will become negatively charged, due to the formation of a Langmuir sheath.
http://farside.ph.utexas.edu/teaching/plasma/Plasmahtml/node41.html
This negative charge will accelerate argon ions into the surface of the object, causing some etching on the surface.
If it's a weak plasma (low ionization fraction) at low temperature for a short time, then the damage might be negligible, or maybe just cosmetic. For a strong high temperature plasma, it will melt or sputter the materials it comes in contact with, and eventually destroy it.
also another thing, is there a way to protect the solid object immersed in plasma? Insulators coating or anything?Khashishi said:A solid object immersed in a plasma will become negatively charged, due to the formation of a Langmuir sheath.
http://farside.ph.utexas.edu/teaching/plasma/Plasmahtml/node41.html
This negative charge will accelerate argon ions into the surface of the object, causing some etching on the surface.
If it's a weak plasma (low ionization fraction) at low temperature for a short time, then the damage might be negligible, or maybe just cosmetic. For a strong high temperature plasma, it will melt or sputter the materials it comes in contact with, and eventually destroy it.
another issue i wish that you could help me with is that i need to calculate the amount of argon gas and the electric current so that when argon gas is transformed to plasma by electric current it exerts pressure X. How do i calculate the amount of gas needed and the amount of electric current needed to exert pressure X assuming it's in a certain container with volume of 10,000 litres. what is the formula itself?Khashishi said:You can cover your things with some sacrificial foil. How long that lasts depends on the parameters of the plasma. Magnetic fields can redirect the plasma so you could use magnets to protect certain parts of your equipment
thank you so much!Khashishi said:Well,
PV = nkT
where n is the density of particles in the plasma. If it's mostly neutral, then n would be the density of argon. I imagine your system is fairly low ionization fraction, so the pressure is probably close to the neutral pressure. But what do I know about your system
'If ionization is significant, then the density would be the sum of the electron density, ion density (of each ionization stage), and neutral density. The electrons and ions and neutrals probably have different temperatures, so you would add them.
##P = P_{ion} + P_{electron} + P_{neutral}##
where ##P_{ion} V = n_{ion} k T_{ion}##, etc...
It's kind of difficult to get quantitatively accurate values for the temperatures and densities of each ionization state. You can try looking at the description of the MIST code
R.A.Hulse, Nucl. Tech./Fus. 3, 259 (1983)
It's for fusion-like temperatures, which I imagine is much hotter than what you are working with, but maybe it could help you understand the equations.