Method for determining absolute plasma parameters

A method for the determination of absolute plasma parameters of unsymmetrical radio frequency (RF) low-pressure plasmas which comprises:

• a) generating an alternating electric field of radio frequency in a plasma reactor by exciting an RF electrode at a driving radio frequency between about 10 MHz and 100 MHz, to create an oscillating discharge current, the discharge current having at least one resonant frequency, the oscillation of the discharge current modified by the electric field resulting from a non-linear space charge sheath adjacent the RF electrode, the oscillation therefore having a Fourier spectrum with peaks at the driving radio frequency and at each resonant frequency of the discharge current;
• b) measuring the radio frequency discharge current generated in said plasma reactor at a portion of said plasma reactor acting as an earth electrode and convening the measured current into electric voltage in the form of analog signals;
• c) converting the analog signals of b) into distal signals;
• and
• d) evaluating the plasma parameters from the digital signals of c) by means of a mathematical algorithm.