A compact design for velocity-map imaging of energetic electrons and ions

We present a compact design for a velocity-map imaging spectrometer for energetic electrons and ions. The standard geometry by Eppink and Parker [Rev. Sci. Instrum. 68, 3477 (1997)] is augmented by just two extended electrodes so as to realize an additional einzel lens. In this way, for a maximum electrode voltage of 7 kV, we experimentally demonstrate imaging of electrons with energies up to 65 eV. Simulations show that energy acceptances less than or similar to 270 and less than or similar to 1200 eV with an energy resolution Delta E/E less than or similar to 5% are achievable for electrode voltages <= 20 kV when using diameters of the position-sensitive detector of 42 and 78 mm, respectively. Published by AIP Publishing.