Novel compact electrostatic ion-current detector using a self-collection method for secondary-electron suppression

For the purpose of observations of the absolute values of ion-end-loss currents for plasma confinement studies in open-field plasma devices, a compact-sized electrostatic ion-current detector is proposed on the basis of a self-collection principle for suppressing the effects of secondary-electron emission from a metal collector. For employing this specific method, it is worth noting that no further additional magnetic systems except ambient open-ended magnetic fields are required for the proposed detector structure. This characteristic property provides a compactness of the total detector system and availability for its use in a plasma confinement device without disturbing plasma-confining magnetic fields. The detector consists of a set of parallel metal plates with respect to lines of ambient magnetic forces of a plasma device for analyzing incident ion currents along with a grid for shielding the collector against strays due to the metal-plate biasing. Availability of the detector is clearly demonstrated in the GAMMA 10 plasma experiments