AbstractThe University of Illinois inertial electrostatic confinement (IEC) device provides 107 2.5-MeV D–D neutrons per second (n s−1), when operated with a steady-state deuterium discharge at 70 kV (G.H. Miley et al., Inertial electrostatic confinement neutron/proton source, in: M. Haines, A. Knight (Eds.), 3rd Int. Conf. Dense Z-pinches, AIP Conf. Proc. 299, AIP Press, New York, 1994, pp. 675–689). Being compact and lightweight, the IEC potentially represents an attractive portable neutron source for activation analysis applications (R.A. Anderl et al., Development of an IEC neutron source for NDE, 16th IEEE/NPSS Symp. Fusion Engineering, IEEE, Piscataway, NJ, 1996, pp. 1482–1485). The plasma discharge in the IEC is unique, using a spherical grid in a spherical vacuum vessel with the discharge formed between the grid and the vessel wall, while the cathode grid also serves to extract high-energy ions. Two key features of the IEC discharge physics are discussed: (1) the formation of ion `microchannels' that carry the main ion flow through grid openings; and (2) the potential well structure formed in the dense central core.