Electronics For The High Resolution Solar Soft X-ray Spectrometer

The high resolution solar soft X-ray spectrometer (SOX) is being developed as one of the six scientific payloads onboard a solar exploration satellite. Its main mission is to measure the solar soft X-ray energy spectrum. The main scientific purpose of the SOX spectrometer is to research on the evolution of thermal plasma and the characteristics of the X-ray radiation of solar flares, to get the continuous spectrum and lines (mainly the Fe XXV line near 6.7keV and the Fe/Ni line near 8keV) of solar flare thermal radiation and to study the changes of the thermal plasma temperature, radiation emission measure and coronal abundances. The SOX spectrometer is also served as a supplementary for the High Energy Burst Spectrometer (HEBS) to measure the solar energy spectrum from low energy X-ray to Gammar ray(1keV～600Mev).The Silicon Drift Detector (SDD) with features of high resolution (better than 130eV@5.9keV), small size, internal integration of refrigeration and high count rate, can precisely measure the middle and low energy X-ray. Therefore two SDD detectors are adopted in SOX spectrometer to measure the solar X-ray spectra in the energy range of 1-15keV and 4-30keV, respectively. The overlapped energy range of 5-10keV can cover the measurement of the Fe/Li ion lines near 6.7keV and 8keV. The prototype of the high resolution solar X-ray spectrometer includes readout circuit for the front detectors, data acquisition unit, payload handling data unit and power supply unit.The physical requirements and project design of the high resolution solar soft X-ray spectrometer are introduced in this article. The electronics hardware and software design of data acquision (DAQ) unit and payload data handling unit (PDHU) are specially described in detail. The DAQ unit is responsible for data acquisition of two detectors, housekeeping data monitoring (voltage, temperature, etc.) and transfering data to PDHU. The PDHU is used to process telecommands, control DAQ system operation and communicate between SOX and satelite on-board data handling (OBDH). A ground test system which is adopted to communicate with SOX payload through LVDS bus and 1553B bus and test the functions of the SOX payload is also designed to simulate the functions of satellite OBDH. The test results are shown that the performences of the prototype of the SOX payload satisfies the physical requirements for solar soft X-ray measurement.The summary for developing the prototype of the SOX spectrometer and the prospects of future work are introduced in the end.