The TPC detector of PandaX-III Neutrinoless Double Beta Decay experiment

The PandaX-III experiment uses a high pressure xenon gas TPC (Time Projection Chamber) to search for the NLDBD~(Neutrinoless Double Beta Decay) of $^{136}$Xe. The Microbulk Micromegas will be used for charge amplification and readout in order to record both the energy and track of an event with high energy resolution and spatial resolution. In the first phase of the experiment, we are building a detector which contains 140 kg 90\% $^{136}$Xe enriched gas operated at 10 bar. The detector will be installed in a dry shielding system at CJPL-II ( China Jin-Ping underground Laboratory II). In this paper, we wil report the design of the PandaX-III detector, including the shielding of the experiment and the components of the TPC: the high pressure vessel, the readout plane and the electric field cage.