Design of an FPGA based TDC readout electronics for prototype Mars ion and neutral Particle analyzer

Abstract

In order to understand the escape of the Martian atmosphere, study the interaction between the solar wind and the Martian atmosphere, and research the acceleration mechanism of neutral particles near the Martian shock, the characteristics of particles in Mars plasma will be explored. A Mars ion and neutral particle analyzer prototype having three functions: Energy analysis, direction analysis and composition analysis, has been developed. A mass spectrometer using Time-of-Flight (TOF) structure based on ultra-thin carbon film, which can obtain a high resolution, has been used to implement composition analysis. Because temperature varies greatly on Mars, in order to distinguish TOF of different particles, the TOF system requires a time resolution of less than 600 ps within the temperature range of-40℃ to +60℃. In this paper, a prototype electronics mainly including a time-to-digital converter (TDC) implemented in Field Programmable Gate Array (FPGA) for mass spectrometer is described. For anti-irradiation considerations, the TDC architecture is implemented in a flash FPGA, and adopted Triple Module Redundancy (TMR) to mitigate Single-Event-Upset (SEU). Online correction is adopted to ensure that TDC can work accurately in the large temperature range. Rom-temperature's test results show that a time resolution of 539ps with a 239 ps RMS was obtained. Thermal tests suggested that the prototype electronics operates well in a temperature range from-40℃ to +60℃ with an RMS less than 305.5 ps.