Readout electronics of a prototype spectrometer for measuring low-energy ions in solar wind plasma

Readout electronics is developed for a prototype spectrometer for in situ measurement of low-energy ions of30 e V/e–20 ke V/e in the solar wind plasma.A low-noise preamplifier/discriminator(A111F) is employed for each channel to process the signal from micro-channel plate(MCP) detectors.A high-voltage(HV) supply solution based on a HV module and a HV optocoupler is adopted to generate a fast sweeping HV and a fixed HV.Due to limitation of telemetry bandwidth in space communication,an algorithm is implemented in an FPGA(field programmable gate array) to compress the raw data.Test results show that the electronics achieves a 1 MHz event rate and a large input dynamic range of 95 p C.A slew rate of 0.8 V/ls and an integral nonlinearity of 0.7-LSB for the sweeping HV,and a precision of less than 0.8 % for the fixed HV are obtained.A vacuum beam test shows an energy resolution of 12 ± 0.7 % full width at half maximum(FWHM) is achieved,and noise counts are less than10/sec,indicating that the performance meets the physical requirement.