The performance of a new Inertial Electrostatic Confinement (IEC) fusion device using a cylindrical anode and two different cathode geometries, spherical and cylindrical, was compared to an existing IEC device with two different sized configurations of spherical anodes and cathodes. Experimental data was generated at -30 to -150 kilovolts, 30 milliamps steady-state, and 0.3 Pascal of Deuterium (D) and/or Helium-3 (3He). The best neutron rate achieved by the new device in a D environment was 2.7 × 107 neutrons per second at 145 kV and 35 mA. In a D-3He environment, the best proton rate achieved was 2.0 × 107 protons per second at 130 kV and 30 mA. Both the D-D neutron rate and the D-3He proton rate were approximately 40% lower than the larger volume existing IEC device.