Low-energy electron transmission through dielectric capillaries

Transmission of electrons with energies from 2 to 10 keV through glass polycapillaries, tubes, and cones was experimentally studied. The dependence of the transmittance on the electron energy, beam current, capillary diameter, and irradiation time was measured. The electron transmittance through polycapillaries decreases with the beam current and measurement time. The results of measurements of the electron and X-ray spectrum at the quartz tube output suggest that a fraction of electrons incident on the wall charge it and ionize wall atoms; other electrons pass through the channel without collision with the wall, since their energy is almost unchanged. It follows from the measurement results that the electron transmission through capillaries is controlled by the potential at the inner channel surface induced by the charge injected during irradiation.