Development And Application Of Langmuir Probe Load System

The ionosphere is the most close to the application level of space physics The state and change of plasma in the ionosphere have an important impact on human communication,navigation,remote sensing positioning and over the horizon radar detection.However,the space-time coverage of ionospheric monitoring is seriously insufficient at present.It is not only unable to give a complete ionospheric plasma distribution,but also unable to give the distribution of plasma density at the time and place of demand.In the space market,with the wide application of small satellites,it provides abundant data resources for ionospheric research,and also brings revolutionary changes for ionospheric research and exploration.At present,the ionospheric detection load in China has not been miniaturized,and it is still dominated by conventional detection load,which can not meet the requirements of small satellite with small size,light weight,low power consumption and easy to carry.In this paper,we independently designed and developed a Langmuir detector payload system with a miniaturized satellite,which can detect the electron temperature,electron density and other parameters of the plasma in the ionospheric environment,and provide accurate and precise in-situ observation data for further understanding of the ionospheric stateThis paper designs a small satellite payload system,which is composed of Langmuir detector and acquisition control system.Langmuir detector is composed of Langmuir probe and rod extension device.Langmuir probe technology is the main method for in-situ detection of space plasma.This system uses Langmuir probe as sensor.In view of the obvious edge effect of traditional Langmuir probe,this paper designs a structure optimization detector based on the relevant probe theory and the detection requirements of ionospheric plasma Planar and cylindrical Langmuir probes can effectively reduce the edge effect at the end of the probe;the collecting electrode of the probe is responsible for absorbing the particle current,and the protective electrode is located at the end edge of the collecting electrode,which has a protective effect on the collecting electrode,avoiding the formation of uneven electric field at the end edge of the collecting electrode,and reducing the influence of the edge effect of the probe.The extension rod is another part of the Langmuir detector.The extension rod is the connecting part between the probe and the satellite.The probe is fixed on the extension rod and is far away from the surface of the satellite through the extension rod.The extension rod can protect the probe from the interference of the satellite body.The acquisition and control system based on STM32 is composed of bias voltage module,current acquisition module,communication module and filter circuit module.The system uses stm32f373 chip with low power consumption and strong function as the controller,which can complete the output of bias voltage,high-speed acquisition of weak current signal,data transmission and other functions.The bias voltage module provides the scanning voltage of-10V-10V for the probe,which is applied to the probe without affecting the collection of particle current;the current acquisition module uses feedback current detection circuit to realize the conversion of current signal to voltage signal;in the filter circuit module,the third-order low-pass filter composed of only a single operational amplifier is used to reduce the power consumption of the system;the filter circuit module uses the feedback current detection circuit to realize the conversion of current signal to voltage signal The voltage signal after the wave is collected by the built-in 16 bit ADC of the controller,which ensures the detection accuracy of the current signal;the communication module completes the acceptance of control instructions and the upload of data.In the software design of the control system,the scanning voltage output of the bias voltage module in the hardware system,multi-channel data acquisition,control command acceptance and data transmission are completed.The system is tested in the ground plasma environment of the Institute of Space Science(ISS)of Shandong University,and the experiments of single probe data acquisition,rationality verification of extension rod and probe decontamination effect are carried out.The feasibility and reliability of the Langmuir probe loading system designed in this paper are verified,which can meet the tasks of easy carrying,low cost,miniaturization and high precision requirement.