Research On Plasma Density Feedback Control System On J-TEXT Tokamak

In this thesis, plasma electronic density feedback control system in tokamak mainly is studied. A new density control algorithm and a new density processing algorithm are used to build the plasma electronic density measurements control system in J-TEXT.In the respect of density processing algorithm, basing on the principium of HCN laser interferometer for electronic density measurement, the beat signal vas detected by TGS detector. Phase shift brought by the Plasma was measured by the Phase comparator. Original HCN signal was collected by high speed data acquisition card PCI9118.The Phase shift signals were collected by the data acquisition card, then according to the properties of the HCN signal, analyses the HCN signal and design a good algorithm for Eliminating Zero drift of signal and signal inversion processing., plasma electronic density with low noise and high precision can be gotten. Using good HCN signal can reconstruct the spatial distribution of electron density more accurately; it provides a good reference to analyses related parameters of plasma.In the respect of density control algorithm, we designed plasma density feedback control system based on Linux&Windows Dual Operating System which is r eal-time feedback control system with communication between upper and lower machines, the core of the system are data acquisition, processing and control in lower machine.To meet the requirements of high speed data acquisition and real-time processing, multi-channel high speed data acquisition card PCI9118 is used to process the acquired signal in real-time, at the same time, the control signal is sent in real-time, it means every the A/D conversion completes for acquisition card, it is required that the converted results which is sent to the data cache in the feedback control software is used to calculate, and then according to calculating results, the feedback control signal will be outputted. To prevent network congestion which caused by transmission of Large Quantities in real-time influence experimenters to monitor the discharge conditions, the impact of laboratory personnel real-time understanding of the discharge, in the design for the upper machine, dual-card structure is used in it. The control system meets the demand of the stability, reality and network functions of the density control systems.