Electron impact heated atomic hydrogen oven

Abstract

The design, construction, and performance of an electron impact heated hydrogen dissociation oven for use in producing an atomic hydrogen gas target for ion–atom collision experiments are described. This novel design utilizes an electron beam focused by a spherical lens system to heat the oven to temperatures in excess of 2400 K. High dissociation fractions are found with cell pressures ≥5 mTorr. The compact design allows placement of an electron spectrometer close to the interaction region (length ∼1.5 cm), as well as direct measurement of the oven temperature by means of an optical pyrometer. The electron beam produces magnetic fields ∼40 mG ∼1 cm from the center of the interaction region. These low magnetic fields offer distinct advantages compared to low-voltage, high-current oven designs when observing relatively low-energy electrons ejected in ion–atom collisions.

Electron capture to the continuum from atomic hydrogen

“…All available experimental data to date has been with non-hydrogenic targets [6,7], which prevented direct comparison of experiment and theory since the most nearly tractable theoretical formulations consider hydrogenic targets. However, an ECC spectrum has now been obtained for 12 MeV C 6+ incident on atomic hydrogen inside a dissociation over heated by electron impact [8,9]. (1)[9,14,18].…”