Effect of Electron Beam on Velocities of Uranium Atomic Beams Produced by Electron Beam Heating

Velocities of uranium atomic beams produced by two types of electron beams, a bent beam and a straight beam, were measured by a laser Doppler-shift technique. The atomic beams were accelerated to 1100 m/s and 900 m/s by free expansion near the evaporation surface with the bent beam and the straight beam, respectively. The higher velocity for the bent-beam evaporator was explained as follows. The evaporated atoms are excited or ionized more efficiently by the electron beam than for the straight-beam evaporator. The excitation and ionization energies contribute to the acceleration of the atomic beam. The attained velocities for the two types of electron beams were roughly estimated using the excitation and ionization energies derived from the electronic stopping power of uranium.