  Photomultiplier tubes (PMTs) with large-area cathodes are increasingly being
used in cosmic-ray experiments to enhance detection efficiency. The optical
modules (OMs) of the High-Energy Underwater Neutrino Telescope (HUNT) have
employed a brand new N6205 20-inch microchannel plate photomultiplier tube
(MCP-PMT) developed by the North Night Vision Science & Technology (Nanjing)
Research Institute Co. Ltd. (NNVT). In order to make the 20-inch PMT fit into
the 23-inch diameter pressure-resistant glass sphere, NNVT improved the
internal structure of PMT and shortened the height of PMT by more than 10~cm.
The first batch of these PMTs has been delivered for preliminary research work.
This paper describes a specific PMT testing platform built for the first batch
of 15 MCP-PMTs, and some performance parameters of PMT, such as peak-to-valley
ratio, TTS and nonliniearity, are measured. The measurement results show that
the new PMT still has good performance and can meet the requirements of HUNT
project.
