Design of real-time data acquisition system for POlarimeter- INTerferometer diagnostic

Abstract

The real-time data acquisition system is designed for providing POlarimeter-INTerferometer (POINT) diagnostic data to P-EFIT in real-time. The digital phase detector of POINT can provide real-time Faraday rotation angle data and density phase shift output which can be used in plasma control. P-EFIT, a code based on parallel computation in Graphic Processing Unit and the EFIT framework, is developed for EAST plasma control. Now P-EFIT includes a new algorithm for real-time plasma current profile reconstruction with POINT diagnostic data. The new real-time data acquisition system has been designed based on a reflective memory (RFM) network and the LabVIEW real-time operating system. It can be divided into three modules: data acquisition, data pre-processing and real-time data transmission. The data acquisition module receives a message containing the plasma shot information from the data acquisition console (according to the rules of the EAST data acquisition system) and then acquires the POINT diagnostic data after signal conditioning. The data pre-processing module primarily converts the raw data into a valid physical signal thus reducing the workload of P-EFIT. The EAST Plasma Control System has a well-established RFM network from which P-EFIT is able to get all the data it needs. This means that the data transmission module must first choose the RFM network to transfer processed data in real-time, and then P-EFIT can perform a new equilibrium reconstruction iteration with the most recent data from the data transmission module and the last equilibrium result. The data transmission frequency is 20 kHz, which satisfies the requirements of the P-EFIT real-time plasma current profile reconstruction.