Development And Application Of Langmuir Probe Diagnostic System

With the increasingly wide application of low-temperature plasma technology in the industry, the control of plasma parameters has received more and more attention. And the control is to be able to obtain accurate information on various parameters of the plasma. Langmuir probe device has became the most widely used diagnostic method of low-temperature plasma, because of its simple structure, low cost, as well as can obtain rich relatively information of plasma. However, at present, the most domestic Langmuir probe systems are build by separative element temporarily, working with manual regulation, not only slow, low accuracy, but do not have a strong anti-interference ability. Therefore, the development of a fully automatic, high accuracy, anti-jamming Langmuir diagnostic system is very meaningful.In this paper, a new type of acquisition card based Langmuir probe diagnostic systems has been designed. The system is mainly constituted with the acquisition card, scan power supply circuit, voltage and current detection circuits, part of hardware for anti-jamming and corresponding software. This system has faster speed and more accurate of measuring for using a new type of acquisition card and a reasonable circuit design, also has stronger antijamming ability for adding an EMC design in the hardware. In terms of software, in addition to the basic function-driven and gathering, but also links to join the digital filter to compensate for the lack of flexibility of the hardware filtering to further improve anti-interference ability of the device, but also make it applicable to a wide range plasma diagnostic.The system has been successfully applied to large area surface wave plasma diagnostics. The VI curve measured is smoothing, and the plasma parameters obtained are reasonable, so the system design is successful. Compared with the traditional ones, this system has faster measuring speed, higher data accuracy, stronger antijamming ability, higher integration, and easy to connect with PC for online data acquisition and offline data analysis.Advice for function and common performance improving of the system is showed in the end of the paper as the reference of the next phase of the work.