This study explores the impact of anode diameter, keeper-to-cathode distance, orifice diameter, and keeper thickness on the discharge characteristics of the open-end emitter heaterless hollow cathode. The study finds that the cathode's keeper orifice diameter positively correlates with discharge voltage, attributed to temperature and plasma drift resistance effects. The discharge voltage at 5 sccm and 4 A condition decreased by 4.9 V when the keeper orifice diameter was reduced by 2 mm. The keeper-to-cathode distance also plays a crucial role; shorter distances result in lower discharge voltage oscillations due to reduced ionization-like instabilities in the cathode plume. At 5 sccm and 4 A, the voltage oscillation decreased by 0.6 V when the keeper-to-cathode distance decreased by 4.8 mm. In high discharge current regimes, the thickness of the keeper orifice requires a higher voltage to sustain the discharge. At 5 sccm and 3 A, the discharge voltage with a 4.8 mm keeper thickness was marginally higher by 0.2 V compared to a 2 mm thickness, while at 6 A, this difference increased to 3.5 V. The findings offer insights into optimizing open-end emitter heaterless hollow cathode designs and lay the groundwork for future studies on cathode plume characteristics.