THE PLASMA SHEATH BOUNDARY WITH FAST MONOENERGETIC ELECTRONS

The behaviour of the plasma-sheath boundary in the presence of monoenergetic electrons is examined theoretically. A Tonks-Langmuir type model is used to investigate the nature of the quasineutral solution for a plasma containing a Maxwellian bulk electron distribution along with an independent source of high-energy monoenergetic electrons. Results indicate that the presence of fast monoenergetic electrons leads to a larger variation of the space potential across the plasma. In addition, it is found that quasineutrality does not break down when the density of monoenergetic electrons in the remote plasma exceeds a critical value (28.5% of the bulk plasma density). © 1990 IOP Publishing Ltd.