Study On Three Electrostatic Probe Diagnosis Technology In Pulse Microwave Plasma

Pulse microwave plasma has many advantages such as high ionization degree, high purity, high activity, wide pressure range, etc. Meanwhile microwave in form of pulse can improve discharge effect, so it has become the focus of research. In order to study the pulse microwave plasma, we should use appropriate diagnostic method. Langmuir probe diagnosis technology is a method in the foundation, so it is applied to pulse microwave plasma diagnosis is very important for related research. Gas in the vacuum chamber generates plasma when inspired by pulse microwave. The plasma has characteristics of pulse, period and transient and the three electrostatic probe diagnosis technology is used to diagnose it.In the diagnosis platform, the specific support system is designed so that probe system and vacuum chamber can stably docking and better discharge will be obtained. In addition, the specific driving system is designed to ensure that the probe can be controlled remotely to reach the specified location in the diagnosis process. In the probe design, the contact area of the probe and the plasma is increased in order to reduce the error signal.In the circuit of diagnosis, due to the high frequency of pulsed plasma, it's necessary to measure the frequency response characteristic of electronics and analysis the probe circuit accurately. In the diagnosis circuit, lumped elements are measured by instrument; the signal line are analyzed by transmission line theory and one test is designed to ensure the signal line's distribution parameters; the analysis of probe line is based on the multi conductor transmission theory and establish a symmetric three parallel transmission line model, meanwhile design an experiment to determine the probe line's distributed parameters.In the calculation method of plasma parameters, there will be a new improvement according to the characteristics of the probe circuit signal. First, the conversion of signal acquisition from time to frequency is finished. Second, the data is taken into the diagnostic circuit to get the signal of probe head. Following, by the plasma parameters calculation method which is improved, the electron temperature and plasma density are obtained.In the platform experiment, obtain the diagnosis data by the probe system, then take result into the plasma parameters calculation formula and obtain the electron temperature and the plasma's density with high time-resolution of 100 ns. At end this diagnostic system has been accepted by the department in contract.