A simple, easily maintained air spark gap of ∼7 nH inductance was developed to switch 0.24 C stored charge at 20 kV in an LC circuit having a period of ∼4 &mgr;sec. A similar 3 nH spark gap with an auxiliary triggering circuit was used to clamp the magnetic flux within the load near the voltage minimum. Voltages up to 30 kV and currents to 5×105A have been handled. Acoustic noise was minimized by completely enclosing the arc, and forced air venting removed corrosive gases and helped control the temperature to improve reproducibility.