Patent ID: 8190366

Claim:
A method for determining an electron density n e of a plasma, comprising: placing a probe into the plasma, the probe comprising a capacitive element connected in series to an inductive element and having a characteristic resonance frequency ω R0 , the probe being connected to a voltage source configured to provide a variable frequency AC voltage to the probe; determining a resonance frequency ω R of the probe within the plasma; and calculating plasma electron density n e at a processor configured to receive and analyze data representative of the probe's characteristic resonance frequency ω R0 , the returned resonance frequency ω R , an electron charge −e, a vacuum permittivity ∈ 0 , and an electron mass m e , where n e = m e ⁢ ɛ 0 e 2 ⁢ ( ω R 2 - ω R ⁢ ⁢ 0 2 ) .