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Volume charge density measuring system

  • US 5,945,831 A
  • Filed: 06/10/1997
  • Issued: 08/31/1999
  • Est. Priority Date: 06/10/1997
  • Status: Expired due to Fees
First Claim
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1. A capacitive sensor for testing a material sample, comprising:

  • an outer conductor having an elongated, substantially tubular shape with a longitudinal axis and first and second ends, and made of an electrically conductive material;

    an inner conductor having an elongated, substantially tubular shape with a longitudinal axis and first and second ends, and made of an electrically conductive material;

    a chamber electrically insulated from said inner and outer conductors having an elongated, substantially tubular shape with a longitudinal axis and first and second ends, said chamber disposed between said inner and outer conductors and coaxially aligned with said inner and outer conductors;

    said outer conductor having an opening in communication with said chamber, said outer conductor defining a shield against penetration by an electric field, said shield completely enclosing said chamber but for said opening in said outer conductor; and

    a valve attached to said opening and having a movable sealing member made of conductive material electrically coupled to said outer conductor, said sealing member selectably movable to open and close said opening.

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