Enhancement of the Gain and Stability in a Discrete Dynode Electron Multiplier Through Differential Voltage Distribution Among Dynodes

We proposed an effective strategy involving a differential distribution of voltages among dynodes to significantly enhance the gain and stability of discrete dynode electron multipliers (DEMs) under continuous electron bombardment. The effects of the differential voltage distribution on the DEM performance were systematically investigated through experiments and numerical simulations. The differential voltage distribution of 7:7:7:7:7:5:5:5:5 enables the DEM to achieve a gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.4\times 10^{{4}}$ </tex-math></inline-formula>, representing a substantial increase by 2.1 times at an operating voltage of 1200 V, and the operating voltage at a gain of 106 to be reduced to 1949 V with a decrease of 186 V in comparison to the traditional uniform voltage distribution of 1:1:1:1:1:1:1:1:1. The gain enhancement is closely related to the increased average secondary electron emission (SEE) coefficients of dynodes D2-D6 and the improved electron collection efficiencies of dynodes D3 and D6. Additionally, the differential voltage also reduced the gain decay rate to 16.7%/mC, reflecting a decrease of 14.8% due to the suppression of SEE degradations in dynodes D7-D9, which can be attributed to their lower average SEE coefficients. Overall, the proposed strategy of differential voltage distribution, characterized by higher voltages among earlier dynodes and lower voltages among latter dynodes, presents a novel and universal approach for optimizing the structure of electron multipliers, addressing the need for highly sensitive and reliable detection of ultraweak or even single charged particles.