Abstract: 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 ?R0 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 ?R, which is different from ?R0 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 ? ? 0 e 2 ? ( ? R 2 - ? R ? ? 0 2 ) .

Abstract: An rf probe is placed within a plasma and an rf signal from a network analyzer for a given dc bias voltage Vp is applied The frequency applied by the network analyzer, ?, is less than the plasma frequency, ?pe, and therefore is not in the resonant absorption range (?=?pe) used to determine electron density in typical rf impedance probe operation. Bias voltages at the applied frequency are applied to the probe in a series of voltage steps in a range which includes the plasma potential. At each bias step, a value of Re(Zac), the real part of the plasma's complex impedance, is returned by the analyzer. A local minimum in the real part of the impedance Re(Zac) occurs where the applied bias voltage Vp equals the plasma potential ?p. The plasma potential ?p can be found by taking the first derivative of Re(Zac) with respect to Vp, ? ( Re ? ( Z a ? ? c ) ? V p , and finding the value of Vp at which ? ( Re ? ( Z a ? ? c ) ? V p = 0 within error tolerances.

Abstract: 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 ?R0 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 ?R, which is different from ?R0 because of the dielectric constant ? of the plasma. The difference in resonance frequencies can be used to determine plasma density ne, when n e = m e ? ? 0 e 2 ? ( ? R 2 - ? R ? ? 0 2 ) .

Abstract: An rf probe is placed within a plasma and an rf signal from a network analyzer for a given dc bias voltage Vp is applied The frequency applied by the network analyzer, ?, is less than the plasma frequency, ?pe, and therefore is not in the resonant absorption range (?=?pe) used to determine electron density in typical rf impedance probe operation. Bias voltages at the applied frequency are applied to the probe in a series of voltage steps in a range which includes the plasma potential. At each bias step, a value of Re(Zac), the real part of the plasma's complex impedance, is returned by the analyzer. A local minimum in the real part of the impedance Re(Zac) occurs where the applied bias voltage Vp equals the plasma potential ?p. The plasma potential ?p can be found by taking the first derivative of Re(Zac) with respect to Vp, ? ( Re ? ( Z a ? ? c ) ? V p , and finding the value of Vp at which ? ( Re ? ( Z a ? ? c ) ? V p = 0 within error tolerances.