Electricity: measuring and testing – Determining nonelectric properties by measuring electric...
Patent
1995-06-07
1998-06-02
Karlsen, Ernest F.
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
324239, 324464, G10N 2700, G01R 3300
Patent
active
057605734
ABSTRACT:
A plasma density monitor is described for determining the ion current of a plasma flowing through a conduit (14). The monitor comprises a plate (18) having a face and an orifice extending from the face through the plate. The internal surface of the orifice conforms with the internal surface of the conduit when the face is adjacent the conduit. The monitor also comprises a detector circuit (22) for sensing the ion current collected by the internal surface of the plate (18). Another embodiment monitors plasma density by determining electrical conductivity in the afterglow of a microwave induced plasma. A resonant LC circuit (50, C3) has a multi-turn coil (C3) surrounding the conduit, an RF oscillator circuit (54, 56) for driving the LC circuit, and a circuit (64, 66, 68, 70, 72, 76) for measuring the decay time of the LC circuit. Plasma flowing through the conduit alters the resistivity of the coil and the time constant of the LC circuit proportional to the electrical conductivity of the flowing plasma.
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Huang Steve Show-Wu
Paranjpe Ajit Pramod
Brady III Wade James
Donaldson Richard L.
Franz Warren L.
Karlsen Ernest F.
Texas Instruments Incorporated
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