Demonstration of 255-kV high-voltage generation with a Cavallo multiplier system

Abstract

Many cryogenic precision measurements require large electric fields in environments where conventional high-voltage feedthroughs are impractical. To address this, we developed a Cavallo electrostatic multiplier designed for in situ high-voltage generation under such conditions. Here, we report a room-temperature demonstration of this device. Using a mechanically translated transfer electrode and a custom rotary field mill for noncontact voltage measurement, the system reached output voltages up to approximately $255~\mathrm{kV}$ from a $25~\mathrm{kV}$ DC-biased input voltage in approximately $600~\mathrm{Torr}$ of SF$_6$. The charging curves are quantitatively described by a capacitance-based model once realistic electrode misalignment is included. Voltage-hold measurements show picoampere-scale leakage currents on long time scales, whereas operation near the maximum voltage is limited by transient discharge processes associated with electrode surface condition and local field enhancement, rather than by the intrinsic dielectric strength of the gas. These results demonstrate the Cavallo multiplier as a viable low-current, in situ high-voltage source and indicate that electrode surface preparation, alignment tolerances, and insulation performance are the principal requirements for reliable operation in future cryogenic implementations.