A Floating Electrostatic Sheath in a Thermally Produced Plasma

Measurements are reported of the plasma density in a highly ionized, thermally produced plasma. A floating electrostatic sheath theory is presented, which predicts that the plasma density is enhanced by several orders of magnitude over the level which would be predicted in the absence of such a sheath. There is agreement between the measured variation of the plasma density as a function of temperature and the predicted behaviour.