Abstract: In response to the demand for small-diameter pulsed neutron logging in petroleum exploration, this study investigates the pulsed operational characteristics of a Penning ion source with an anode diameter smaller than 10 mm. The focus is on how the distribution of magnetic induction strength and the structure of the discharge gap affect the pulse amplitude-time characteristics of the small-diameter Penning ion source. The results show that by increasing the magnetic induction strength of the anticathode gap to a level comparable to that of the cathode gap, the pulse current amplitude can be raised above 1 mA, and the delay time can be reduced to less than 20 μs. The discharge enhancement brings about the phenomena of unstable pulse discharge and amplitude jumps, which are significantly affected by the fine tuning of the cathode gap and the anticathode gap. With a cathode gap of 1.0 mm and an anticathode gap of 2.0 mm, the ion source can achieve favorable current amplitude, delay time, and voltage range for stable discharge. Within a pressure range of 7.0×10⁻² Pa to 2.0×10⁻¹ Pa, the ion source can deliver current amplitudes between 1 mA and 3.5 mA, with delay times maintained below 20 μs, and a minimum delay time of 5 μs.