We made a nagative glow lamp (having no positive column), measured the plasma characteristics of that lamp, and found that the characteristics of this plasma depend only on the distance from the cathode, and that there seems to be two groups of electrons in the negative glow.
We therefore made the following hypotheses.
(1) There are two groups of electrons in this plasma, here called first electrons and second electrons. The first electrons are emitted from the cathode and accelerated by the electric force of the ion sheath. They collide with nothing in the ion sheath, and their energy in the plasma is determined by the cathode fall voltage. The second electrons are the electrons created by two ways. One way is as a result of the inelastic collisions of the first electrons and neutral atoms. Another way is as a result of the ionization between other second electons and excited atoms. And they disappear by ambipolar diffusion.
(2) In this plasma there is not the accelerating electric field, which exists in the positive column, but there is the electric field produced by diffusion. The second electrons are given their energy by the collision of electrons, not by the electric field. And the energy of the second electrons is constant in any place of lamp.
we calculated the continuity of the electron density, the continuity of the current, and the continuity of the energy, and we got results that agreed with the measurement results.
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