Mechanism for negative‐ion production in the surface‐plasma negative‐hydrogen‐ion source

摘要: The system parameters and surface adsorption conditions of the surface‐plasma negative‐hydrogen‐ion source are reviewed. A mechanism is developed for production negative ions by incident energetic hydrogen atoms backscattering from a cesiated tungsten surface. active electronic level during course collision approximated as sum electron affinity cesium hydride molecular ion image potential. model predicts negative‐ion formation atomic collisions with all alkali‐coated surfaces alkalis sodium through cesium. In case lithium, does not apply due to breakdown potential approximation close Negative‐ion also expected occur positive which backscatter substrate neutrals. energy thresholds established.