Intensity of a source of atomic hydrogen based on a hot capillary

A source of atomic hydrogen incorporating a hot capillary was fabricated and investigated. The absolute and angularly resolved intensity of atomic hydrogen is derived from three experimentally determined quantities: (1) the flow rate of the hydrogen feed gas, (2) the degree of dissociation, and (3) the angular distribution of the emitted hydrogen atoms. The measurement of quantities (1) and (2) is reported here, quantity (3) has been investigated previously. The intensity of atomic hydrogen depends on the temperature of the capillary and the gas flow rate. At a temperature of 2600 K and a flow rate of 8 x 10(-3)mbar l/s the center-line intensity is about 4 x 10(17)atoms/sr s. This is about four times the center-line intensity from a thin-walled aperture subjected to the same total flux. The enhancement is due to beam formation by the capillary and is even more pronounced at lower flow rates. (C) 2000 American Institute of Physics. [S0021-8979(00)03404-6].