End-boundary sheath potential, Langmuir waves, electron and ion energy distribution in the low pressure DC powered Non-ambipolar Electron Plasma

The non-ambipolar electron plasma (NEP) is heated by electron beam extracted from the electron-source Ar plasma through a dielectric injector by an accelerator located inside NEP. NEP pressure is in the 1-3mTorr range of N$_{2}$ and its accelerator voltage varied from $V_{A}=+$80 to $V_{A}=+$600V. The non-ambipolar beam-current injected into NEP is in the range of 10s Acm$^{-2}$ and it heats NEP through beam-plasma instabilities. Its EED$f$ has a Maxwellian bulk followed by a broad energy-continuum connecting to the most energetic group with energies above the beam-energy. The remnant of the injected electron-beam power terminates at the NEP end-boundary floating-surface setting up sheath potentials from $V_{S}=$80 to $V_{S}=$580V in response to the applied values of $V_{A}$. The floating-surface is bombarded by a space-charge neutral plasma-beam whose IED$f$ is near mono-energetic. When the injected electron-beam power is adequately damped by NEP, its end-boundary floating-surface $V_{S}$ can be linearly controlled at almost 1:1 ratio by $V_{A}$. NEP does not have an electron-free sheath; its ``sheath'' is a widen presheath that consists of a thermal presheath followed by an ``anisotropic'' presheath, leading up to the end-boundary floating-surface. Its ion-current of the plasma-beam is much higher than what a conventional thermal presheath can supply. If the NEP parameters cannot damp the electron beam power sufficiently, $V_{S}$ will collapse and becomes irresponsive to $V_{A}$.