Electrode Design for a Cavallo High Voltage Multiplier in a Cryogenic nEDM Experiment

Marie A. Blatnik; Steven M. Clayton; Bradley W. Filippone; Takeyasu M. Ito; Nguyen S. Phan; Christopher M. O'Shaughnessy; John C. Ramsey

arXiv · 2604.10313

Electrode Design for a Cavallo High Voltage Multiplier in a Cryogenic nEDM Experiment

Marie A. Blatnik·Steven M. Clayton·Bradley W. Filippone·Takeyasu M. Ito·Nguyen S. Phan·Christopher M. O'Shaughnessy·John C. Ramsey

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Abstract

The Cavallo multiplier [http://archive.org/details/b28771035_0003] is an electrostatic inductance machine that can generate low-noise high voltages electrically isolated from its voltage input, making it ideally suited for precision experiments. Its in-situ production makes it especially useful in cryogenic experiments, where the use of traditional feedthroughs is challenging due to thermal, electrical, magnetic, and physical size considerations. One such experiment is a cryogenic measurement of the neutron electric dipole moment (nEDM) [arXiv:1908.09937,arXiv:2512.14975], which requires several hundred kilovolts on a measurement cell electrode in 0.4 K liquid helium (LHe). A Cavallo multiplier can generate this voltage by stepping up a smaller input (e.g., 50 kV) from a feedthrough. We designed Cavallo electrodes using finite element analysis to provide high voltage gain and low probability of electrical breakdown in the experimental apparatus. The final geometry achieves a gain of 18, providing a target of 650 kV with peak electric fields of 116 kV/cm distributed over small areas to limit breakdown risk.

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Marie A. Blatnik, Steven M. Clayton, Bradley W. Filippone, Takeyasu M. Ito, Nguyen S. Phan, Christopher M. O'Shaughnessy, John C. Ramsey. 2026-04-11. Electrode Design for a Cavallo High Voltage Multiplier in a Cryogenic nEDM Experiment. https://arxiv.org/abs/2604.10313

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