EAST Error Field Data Acquisition And Real-Time Calculation System

Tokamak is a toroidal magnetic confinement nuclear fusion experimental device,which generates a confined magnetic field to the plasma through the effect of various conductor currents and the plasma current.The balance and stability of the magnetic field are considerable to the experiment.However,in engineering practice,various factors such as coil position deviation,induced current in the conductors,ferromagnetic material,artificial external field,and unstable perturbation in the plasma may cause the magnetic field to no longer be axisymmetric and form an error field.A tiny toroidal asymmetry of the magnetic field can have a sensitive effect on the stability of the plasma.Therefore,it is of great significance to study the data acquisition and real-time calculation about the error field.In order to accurately correct the EAST error field in real time and meet the requirements of higher plasma operating parameters in the future,it is necessary to obtain the real-time calculation results of the error field firstly.For this purpose,this paper designs and implements a stable and reliable data acquisition and real-time calculation system.According to the method of plasma response to the error field,the amplitude and phase information of the error field can be obtained through calculating the toroidal magnetic field perturbation of the plasma in real time.The system is based on the multi-process mechanism of Linux to ensure that the acquisition and calculation of multi-tasks are performed efficiently at the same time.Using the ADLINK PXI-2022 multi-channel synchronous acquisition board,it acquires the measured signals that have been amplified by integrators.Through the application of related technologies such as double-buffering scheme,shared memory,semaphore synchronization,and reflective memory,It completes the real-time calculation every slice of 100us.Finally,it realizes data storage and display through the MDSplus database.After running and testing the system,the amplitude and phase of the corresponding mode of the error field can be accurately obtained and the expected purpose is achieved.The system realizes the function of data acquisition and real-time calculation of the EAST error field,which provides correct and reliable data source and engineering practice basis for the correction of the error field and other related research.