Current Density Probes

Our current density probes come in planar-styles and aperture-styles. These probes usually determine absolute levels of ion current density. Our probes feature small dimensions, simple construction, and easy setup. Plasma Controls can provide custom cables, feed-thrus, and measurement equipment to meet specific needs.

Theory of Operation

Planar-Style Probes

A planar current density probe of stainless-steel construction.
A planar probe of low-sputter-yield graphite construction, featuring a low-noise rear triaxial connector.
A planar, or "nude," style probe has an open-faced collector of known area, closely surrounded by a guard ring. The collector and guard ring are typically biased 10 to 100 V negative of ground to repel electrons and measure ion current in an ion saturation regime.

Aperture-Style Probes

Our aperture, or "collimated," style probe has a reduced entrance area, admitting particles through a hole of known diameter in a thin plate. As with the planar probe, the collimator and collector are biased 10 to 100 V negative of ground to measure ion current. In some cases, the collector can be biased positive to reject charge exchange ion content.

Example Measurement

The image at right shows a current density probe placed downstream of a Hall-effect electric propulsion thruster. The probe is mounted on a translation stage, and is collecting current density data from the thruster's plume.

Example Measurement

The image at right shows a nude-style current density probe just downstream of a small 3-cm beam diameter ion source. The probe is mounted on a translation stage, and is measuring the beam's divergence.