Reply To: 50 years… hmm

[Lerner]

I did answer your question, but evidently not clealry enough. There is no 200 torr limit. You must decrease the lenght of the anode, here labled z, when you increase the pressure, because the sheath rund more slowly, so it have moved a shorter distance by the time the pulse peaks. Roughly density goes up as the square of the length goes down. So, since you can’t make the anodes much shorter than 7 cm on this machine, this sets a rough upper limit on the pressure. But you can play around beyond 200 torr. Ultrahihg pressures are out for the reasons stated here and in the last message. With too high presure, you devote all your energy to ionization–there is none left over for the motion of the sheath.