Bipolar ionic current probe unit and method for measuring positive and negative current densities by means of the same probe unit

Claim 1

A bipolar ionic current probe unit comprising: a tri-electrode probe, which includes a narrow elongated central electrode insulatively disposed on an imaginary surface of a small shape having a plane of symmetry along a line of intersection between said imaginary surface and said plane of symmetry, and a pair of measuring electrodes insulatively disposed on said imaginary surface portions on the opposite sides of said central electrode in a symmetric manner with respect to said line of intersection so as to cover substantially the entire imaginary surface portions on the opposite sides with a small fixed gap clearance spaced from said central electrode; a hollow metallic support post for insulatively supporting said tri-electrode probe; and a measuring system which includes individual electric conductors respectively connected to said said central electrode and said measuring electrodes and extending through the hollow space in said hollow metallic support post as insulated from said hollow metallic support post and from each other, means for measuring minute electric currents with one end connected to said individual electric conductors and the other end connected through a common electric conductor to said hollow metallic support post, and a variable D.C. voltage source connected between said common electric conductor and a reference potential point.

Claim 3

A method for simultaneously and individually measuring positive and negative ionic current densities within an electric field where both positive and negative ions coexist by mean of a bipolar ionic current probe unit comprising a tri-electrode probe, which includes a narrow elongated central electrode insulatively disposed on an imaginary surface of a small shape having a plane of symmetry along a line of intersection between said imaginary surface and said plane of symmetry and a pair of measuring electrodes insulatively disposed on said imaginary surface portions on the opposite sides of said central electrode in a symmetric manner with respect to said line of intersection so as to cover substantially the entire imaginary surface portions on the opposite sides with a small fixed gap clearance spaced from said central electrode, a hollow metallic support post for insulatively supporting said tri-electrode probe, and a measuring system, which includes individual electric conductors respectively connected to said central electrode and said measuring electrodes and extending through the hollow space in said hollow metallic support post as insulated from the hollow metallic support post and from each other, means for measuring minute electric currents with one end connected to said individual electric conductors and the other end connected through a common electric conductor to said hollow metallic support post, and a variable D.C. voltage source connected between said common electric conductor and a reference potential point; consisting of the steps of: positioning said tri-electrode probe at a measuring point within said electric field as oriented in such direction that said plane of symmetry is directed in perpendicular to the direction of said electric field with one of said measuring electrode opposed to a source of negative ions and the other measuring electrode opposed to a source of positive ions; varying the voltage of said variable D.C. voltage source to change the potentials of the central electrode and the measuring electrodes in said tri-electrode probe as well as said hollow metallic support post until said minute electric current measuring means detects substantially zero current flowing through the individual electric conductor connected to said central electrode; then measuring the minute electric currents flowing through the individual electric conductors connected to said respective measuring electrodes; and deriving the positive and negative ionic current densities, respectively, on the basis of the measured values of said minute electric currents flowing through the individual electric conductors connected to said respective measuring electrodes.

Claim 4

A method for simultaneously and individually measuring positive and negative ionic current densities within an electric field where both positive and negative ions coexist by mean of a bipolar ionic current probe unit comprising a tri-electrode probe, which includes a narrow elongated central electrode insulatively disposed on an imaginary surface of a small shape having a plane of symmetry along a line of intersection between said imaginary surface and said plane of symmetry and a pair of measuring electrodes insulatively disposed on said imaginary surface portions on the opposite sides of said central electrode in a symmetric manner with respect to said line of intersection so as to cover substantially the entire imaginary surface portions on the opposite sides with a small fixed gap clearance spaced from said central electrode, a hollow metallic support post for insulatively supporting said tri-electrode probe, and a measuring system, which includes individual electric conductors respectively connected to said central electrode and said measuring electrodes and extending through the hollow space in said hollow metallic support post as insulated from the hollow metallic support post and from each other, means for measuring minute electric currents with one end connected to said individual electric conductors and the other end connected through a common electric conductor to said hollow metallic support post, and a variable D.C. voltage source connected between said common electric conductor and a reference potential point; consisting of the steps of: positioning said tri-electrode probe at a measuring point within said electric field as oriented in such direction that said plane of symmetry is directed in perpendicular to the direction of said electric field with one of said measuring electrode opposed to a source of negative ions and the other measuring electrode opposed to a source of positive ions; varying the voltage of said variable D.C. voltage source to change the potentials of the central electrode and the measuring electrodes in said tri-electrode probe as well as said hollow metallic support post until said minute electric current measuring means detects substantially zero current flowing through the individual electric conductor connected to said central electrode; then measuring the minute electric currents flowing through the individual electric conductors connected to said respective measuring electrodes; and deriving the positive and negative ionic current densities, respectively, on the basis of the measured values of said minute electric currents flowing through the individual electric conductors connected to said respective measuring electrodes.