New answers tagged

1

Breakdown depends on an 'Avalanche' taking place: positive ions formed by electrons being knocked out of molecules, and negative ions formed by the knocked-out electrons sticking to neutral molecules, are accelerated by the electric field. If they gain enough KE before colliding with other molecules they will cause more ions to be formed. These will also be ...


0

The overall charge on a conducting sphere does not create an electric field inside the sphere, this is something many beginners ask about. But a plasma is by definition ionized. Electron mobility is higher than the ion mobility, and so the outer region of the plasma will accumulate a small positive charge while the inner surface of the sphere picks up a ...


1

Why does the transverse Alfven mode not undergo wave steepening and hence resulting in shock waves? Because it is a transverse oscillation. Nonlinear steepening happens in longitudinal oscillations. As long as the Alfven mode remains transverse, it cannot steepen. Look at your Equation 6.5.18. If you apply the variational principle to the right-hand side,...


1

I used to design and test RF impedance matching units for plasma generation. The matching unit is essentially a resonant LC network, tuned to the RF frequency and delivering an output impedance to match that of the plasma chamber; the resonant frequency and output impedance are interdependent. As you note, the chamber impedance changes dramatically on ...


1

One way to do a crude match is to have a dropping resistor in series with the RF so that when the plasma ignites and its resistance drops, the resistor "catches" the load and limits the current. The reason I suggest this is that although fully automatic impedance matchers are in use for ham radio transmitters, it takes several seconds for the ...


0

First of all, without something to contain it, any cloud would quickly disperse in seconds due to the thermal speed of the atoms. And if you put it in an actual container, you would block either any ionizing photons or particles or both. So realistically, you really need gravity to contain the cloud if you want to have it ionized. Now as for the dominant ...


1

I often hear about a beam of particles on top of a background population in plasma physics. What does exactly beam mean? Many astrophysical plasmas are, at best, weakly collisional. This means that two populations can stream past each other with few or no collisions. In such a scenario, it is appropriate to define the different populations within each ...


0

I did some more thinking and digging: I think the Saha equation is not necessarily the right way to answer this question, as it requires the gas be in thermal equilibrium, which may or may not be the case in a space environment. A better back-of-the-envelope method might be to try to follow the recombination rate = ionizing photon rate method that is often ...


Top 50 recent answers are included