Abstract: [Background] The 7.62cm (3-inch) photomultiplier tube (PMT) is an important component of the Jiangmen Underground Neutrino Observatory (JUNO) giant detector, which will work as an independent detection system for the physics measurements, and will calibrate as well as crosscheck the 50.8cm (20-inch) PMT detection system. It is required that the single-channel current supply of each 7.62cm PMT high voltage does not exceed 10 μA.[Purpose] This study aims to reduce the performance requirements of the high-voltage power supply system and improve the reliability of the system.[Methods] The effects of different high-voltage currents on the detection performance of the 7.62cm PMT are studied by experiments. Three kinds of high voltage current dividers were used to test the performance of an HZC XP72B20 7.62cm PMT sample (serial number 70069), including gain, energy resolution, peak to valley ratio and non-linearity of the anode output signal.[Results] The change of the divider current has negligible impact on these probing performances.[Conclusions] This result provides an important experimental reference for the use of small divider current in the JUNO detector for the 7.62cm PMT.

Key words: Photomultiplier tube, Divider current, Single photoelectron spectrum, Nonlinearity