ELECTRON CURRENT TO A CYLINDRICAL PROBE IN A MOVING HIGH-PRESSURE PLASMA

A theoretical expression has been developed for the electron current w hich flows to a positively biased cylindrical probe immersed in a movi ng, high pressure plasma. Experimental results obtained with an atmosp heric pressure plasma show good agreement with the theory and are simi lar to those obtained recently by other experimenters. Essentially, th e theory states that under given conditions, namely, where the sheath convection mode is dominant, the electron current to a negatively bias ed probe is approximately equal to the ion current that would flow to a negatively biased probe multiplied by a factor equal to the ratio of the electron and ion mobilities. A separate measurement of the thickn ess of the electron sheath is also found to be in good agreement with the theory. Because of the much higher magnitude of the electron curre nt to a probe (versus the ion current), electron current measurement c an provide far more accurate data in many circumstances.