Volume Production of High Negative Hydrogen Ion Density in Low-Voltage Cesium-Hydrogen Discharge

The work is dedicated to the theoretical and experimental investigation of the intensive H- volume-plasma generation in cesium-hydrog en discharge. A low-voltage (LV) mode of the discharge, a LV arc with a heated cathode, is studied. Theory of the discharge was created. It was shown theoretically that very high - H concentration ( - H N ~ 10 13 cm-3) may be achieved in the discharge plasma. A comparison between the discharge theory and the experiments was fulfilled. The main plasma parameters were measured by probe method. The - H concentration in plasma was determined from the experimentally measured absorption of laser radiation due to the photodetachment of electrons from - H ions. The existence of a very high - H concentration (~ 1013 cm-3) in plasma was proved experimentally. Theoretical modeling shows that, with a high electron emission from the cathode ( 10 A/cm2), the maximum - H density is located in plasma near the anode. It allows extraction of narrow and bright - H beam through a small opening in the anode.