Abstract: An ion balance monitor for simultaneous monitoring of the positive and negative ion production rates, and therefore ion concentration, by measurement of currents resulting from the presence of airborne ions as created for example by an air (gas) ionizer. Additionally it examines the ion balance by comparing the aforementioned currents. Information acquired in this way can be used in real time monitoring of the ionizer. Ion balance and production rate of ions of both polarities can be recorded by the ion monitor, regardless of the type of the ionizer. The ion monitor can provide a feedback signal needed to keep an ionizer system in balance.

Abstract: A non-contacting electrostatic voltmeter (ESVM) technique and apparatus having a spacing-independent dynamic response characteristic. Using the disclosed technique, an ESVM apparatus is capable of detecting and measuring electrostatic voltages and/or fields over wide variations of sensing probe to measured surface spacing with little or no variation in the dynamic response (speed and waveform) of the reported electrostatic voltage being measured. Disclosed is a feedback circuit that provides the spacing independence of the speed of response of an electrostatic voltmeter. In particular, the method and apparatus of the invention provides an AC-type auxiliary feedback loop that provides a means for a DC-feedback electrostatic voltmeter to maintain a fixed gain and thus stable response of the DC loop over a broad range of distances between the sensing electrode and measured surface.

Abstract: An ion balance monitor for simultaneous monitoring of the positive and negative ion production rates, and therefore ion concentration, by measurement of currents resulting from the presence of airborne ions as created for example by an air (gas) ionizer. Additionally it examines the ion balance by comparing the aforementioned currents. Information acquired in this way can be used in real time monitoring of the ionizer. Ion balance and production rate of ions of both polarities can be recorded by the ion monitor, regardless of the type of the ionizer. The ion monitor can provide a feedback signal needed to keep an ionizer system in balance.

Abstract: A sensor for an electrostatic detector including an elongated vibratory element supported at a mechanical node at one end in the manner of a cantilever beam, a sensitive electrode on the vibratory element near the other end and adapted to be disposed toward an electrical charge, field or potential being measured, and a driver transducer on the vibratory element for vibrating the element in a direction to vary the capacitive coupling between the electrode and the electrical charge, field or potential being measured. An amplifier and the sensitive electrode are combined in an assembly on the vibratory element thereby providing a low impedance amplifier output which in turn allows a narrow spacing around the vibratory element to prevent entry of contaminants. The vibratory element can be provided with a structure which allows measurements with various spatial resolution characteristics.

Abstract: A sensor for an electrostatic detector including an elongated vibratory element supported at a mechanical node at one end in the manner of a cantilever beam, a sensitive electrode on the vibratory element near the other end and adapted to be disposed toward an electrical charge, field or potential being measured, and a driver transducer on the vibratory element for vibrating the element in a direction to vary the capacitive coupling between the electrode and the electrical charge, field or potential being measured. The driver transducer is at a location along the beam and is operated at a vibratory frequency such that a virtual mechanical node appears along the beam. This, in turn, reduces vibration at the mechanical attachment node so that the degree of stiffness of the mechanical node does not affect the operating frequency and/or the displacement at the free end of the cantilever.

Abstract: A sensor for an electrostatic detector comprising an elongated vibratory element supported at a mechanical node at one end in the manner of a cantilever beam, a sensitive electrode on the vibratory element near the other end and adapted to be disposed toward an electrical charge, field or potential being measured, and a driver transducer on the vibratory element for vibrating the element in a direction to vary the capacitive coupling between the electrode and the electrical charge, field or potential being measured. The driver transducer is at a location along the beam and is operated at a vibratory frequency such that a virtual mechanical node appears along the beam. This, in turn, prevents vibration of the mechanical node so that the degree of stiffness of the mechanical node does not affect the operating frequency and/or the displacement at the free end of the cantilever.

Abstract: A sensor for an electrostatic detector comprising an elongated vibratory element supported at a mechanical node at one end in the manner of a cantilever beam, a sensitive electrode on the vibratory element near the other end and adapted to be disposed toward an electrical charge, field or potential being measured, and a driver transducer on the vibratory element for vibrating the element in a direction to vary the capacitive coupling between the electrode and the electrical charge, field or potential being measured. The driver transducer is at a location along the beam and is operated at a vibratory frequency such that a virtual mechanical node appears along the beam. This, in turn, reduces vibration at the mechanical attachment node so that the degree of stiffness of the mechanical node does not affect the operating frequency and/or the displacement at the free end of the cantilever.