A. S. Kupriyanov

Negative hydrogen ion production in the hollow cathode Penning surface‐plasma source

A small hollow cathode Penning surface‐plasma source (SPS) was developed and studied. The H− yield was proportional to the emission apertures area and increased over a wide range of discharge current. The H− yield, with an intensity of up to 0.95 A and an emission current density of up to 3.6 A/cm2, was obtained in a pulsed mode. With the discharge current of 20 A and a pulse duration of 60 s, an H− yield with current of 0.1 A was obtained. The H− emission current density had approximately the same value for various diameters (0.5–7 mm) and thicknesses (0.3–4.0 mm) of cylindrical emission holes, if the thickness of hole walls did not exceed the hole diameter. The H− yield extracted through the thick conical emission holes had a value 25% higher than that for a thin cylindrical hole with the same permeable diameter. Dependencies of the H− yield versus magnetic field and hydrogen feed were different from that of the standard Penning SPS. The optimal cesium coverage of the electrodes was stable for both high...

Long‐pulsed surface‐plasma sources with geometrical focusing

We describe models for the long‐pulsed surface‐plasma multiaperture quasi steady‐state with a hydrogen negative ion output of up to 1 A, with an emission current density of 2 A/cm2, and with an average current density in a beam of 60 mA/cm2. The gas efficiency for the production of H− beams was 12–17%. The experimental and the simulated efficiencies of the negative ion production of pure hydrogen and cesiated surface‐plasma sources with geometrical focusing are compared.

Surface‐plasma sources with an intense cathode and anode productions of negative ions

Two types of the surface‐plasma sources of negative hydrogen ions developed at Budker Institute of Nuclear Physics are discussed. The source characteristics and the mechanism of negative ion production are presented. It is shown that several channels of plasma particle surface conversion and desorption are responsible for an intense negative ion production in these sources. The results of a detailed study of the quasistationary honeycomb and its comparison with the data for hollow‐cathode Penning sources are presented.

High-current surface-plasma negative-ion sources with geometrical focusing

Long‐pulsed surface plasma multiaperture models with hydrogen negative‐ions output of up to 1 A and with an average current density of 60 mA/cm2 are described. The experimental and simulated negative‐ion production efficiencies of pure hydrogen and cesiated surface‐plasma sources with geometrical focusing are compared.

MULTIBEAM HONEYCOMB SURFACE-PLASMA SOURCE WITH PLASMA INJECTION FROM HOLLOW CATHODES

The small model of scaled honeycomb surface-plasma source for intense multibeam H−(D−) ion production was studied. The increased sizes of the honeycomb cells (to 3×3 cm2) and of discharge layer thickness (to 1.5 cm) were tested. The plasma injection from the hollow hydrogen–cesium cathodes was used for a high-current semiplanotron discharge uniform operation at a low gas pressure. An optimal hydrogen pressure was about 1 Pa at maximal negative ion production. Extraction of H− ions from four emission apertures of 4×10 mm size each produces four elementary H− beams with intensity up to 100 mA each. No essential isotopic effect was found—the intensity of D− beams had about the same value (when discharge was operated in deuterium).

Multiampere negative ion source development at Novosibirsk (invited)

Results on multiampere negative ion (NI) sources with a surface‐plasma mechanism of negative ion production are presented. Several types of surface‐plasma sources (SPS)—Honeycomb semiplanotrons and hollow‐cathode Penning source—are reviewed. The data on SPS H−(D−) production with average NI current density in the beam up to 0.1 A/cm2 is presented. The properties of high‐current glow hydrogen–cesium discharge that produces a large‐area, thin layer of plasma and provides the necessary components for intense negative ion emission and collecting (low work function coverage, electric and magnetic field distribution across the plasma, current composition to NI emitter) are analyzed. Data on efficiency and contribution of different channels of surface‐plasma NI production are presented.

Hollow cathode Penning SPS with anode H− production

We fabricate a new small hollow−cathode Penning SPS with a multiaperture extraction for the anode N1 production study. It was found, that the anode surface conversion of superthermal and fast hydrogen atoms into H− ions is effectively realized in the Penning SPS in the case of an increased, cesiated anode surface. (AIP)