This study proposes an improved high-voltage fast impulse generator based on an inductive energy storage system with a 4 kV static induction thyristor. Nanosecond-scale impulses with pulse widths below 100 ns and a peak voltage of up to 15 kV can be generated by modifying the high-voltage transformer in the circuit and tuning the circuit capacitor. The resulting device is highly stable and can perform continuously if the discharge parameters are chosen within the recommended range. A plasma jet was operated using the generator at low temperature (below 37 °C). Together with its high stability and potential for continuous operation, the proposed generator offers promise for use in biomedical and agricultural applications. Furthermore, the nanosecond-scale high-voltage impulses produced by the generator enable it to achieve an electron density in the plasma one order of magnitude higher than the commercially available radio frequency plasma jet analog. We also show how to reduce the total cost of the generator.