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Measurements have been made of the current circulating through a plasma and an adjacent electrically isolated conductor containing an electron‐emitting surface region. This ‘‘unipolar’’ current (so called since it requires only a single electrode) was measured in a dc mercury–argon positive column plasma (7 mTorr Hg, 3 Torr Ar, 1.8 cm radius, 400 mA). The unipolar conductor consists of metal disks located at the boundary of the plasma; these disks include indirectly heated dispenser cathodes which act as the electron‐emitting regions, providing external control of the emission level. The disks can be connected externally in various combinations to form a conductor of variable distribution and area or they can be used as independent electrostatic probes. Measured unipolar currents are in good agreement with values predicted from individual experimental probe V‐I characteristics for the disk emitters and collectors, demonstrating that the unipolar current circulation process can be interpreted in terms of electrostatic probe characteristics.