Patent ID: 7696758
Filing Date: 2010-04-13
Classification: H05H

Abstract:
1. A plasma diagnostic apparatus including a probe unit inserted into a plasma or disposed at a boundary of a plasma, the apparatus comprising: a signal supplying unit having a signal supplying source; a current detecting/voltage converting unit for applying a periodic voltage signal applied from the signal supplying unit to the probe unit, detecting the magnitude of the current flowing through the probe unit, and converting the detected current into a voltage; and a by-frequency measurement unit for receiving the voltage output from the current detecting/voltage converting unit as an input and computing the magnitude of individual frequency components of the current flowing through the probe unit; wherein an ion density (ni) of the plasma is computed from the computed individual frequency components of the current by following Equation: where Te is an electron temperature, Vsh is the magnitude of the sheath voltage between a probe unit and a plasma, A is a probe area, and ikw is a magnitude of kth harmonic frequency of the current flowing through a probe unit.