LC resonance probe for determining local plasma density

摘要

An apparatus and method for determining plasma parameters such as plasma electron density ne. The probe apparatus includes an LC resonance probe comprising an inductive element and a capacitive element connected in series. The capacitive element of the probe can be in the form of a parallel plate capacitor, a cylindrical capacitor, a spherical capacitor, or any other suitable capacitor. The configuration of the probe apparatus gives it a characteristic resonance frequency ωR0 which can be determined by a circuit analysis device. When the capacitive element of the probe apparatus is placed in a plasma, the probe exhibits a new resonance frequency ωR, which is different from ωR0 because of the dielectric constant ∈ of the plasma. The difference in resonance frequencies can be used to determine plasma density ne, where n e = m e ⁢ ɛ 0 e 2 ⁢ ( ω R 2 - ω R ⁢ ⁢ 0 2 ) .