Current Density Probes

Our current density probes come in a nude-style and a collimated-style. These probes determine absolute levels of 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.

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Theory of Operation

Nude-Style Probe

A 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.

Collimated-Style Probe

Our collimated-style probe has a reduced entrance area, admitting particles through a hole of known diameter. As with the nude probe, the collimator and collector are biased 10 to 100 V negative of ground to measure ion current.

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.