Real-time Display System to Monitor Plasma Shape and Position During the Discharge of the Tokamak

Md Mahbub Alam

doi:10.11648/j.ijem.20190301.13

Abstract

A novel, efficient and precise real-time display system to monitor the plasma shape and position during the discharge of the tokamak has been offered in this study for the observation of the continuous behavior of the plasma that is produced inside the vacuum vessel. The observed behavior of the plasma can provide indications for the control and operation of the tokamak to achieve long time discharge. The display system can display the plasma cross-sectional view of the last closed flux surface (LCFS) with the position of the vacuum vessel wall and the X-points position with the setting of the divertor plates at a big screen in real-time. The display system offers not only the visual image of the plasma but also time evolution graphs of various plasma parameters such as the plasma current (IP), poloidal field coils currents (IPF), emission of Hα, transport of the oxygen impurity, major radius (R), minor radius (a), plasma elongation (κ) and triangularity (δ) in real-time. For the remote participation to the experiments, the display system has a subsystem that can record the entire display frame and the time evolution graphs of the various plasma parameters as video files. The recorded video files are accessible through online by the remote participants during the operation of the tokamak. In addition, the display system has an emergency safety notification system that can identify the critical condition of the tokamak during its operation and can notify the occurrences of any critical or abnormal situations by generating an alarm. The overall display system and its subsystems have been designed and integrated with the real-time hardware equipment of the National Instruments Corporation (NI) and the entire data acquisition and computational systems have been developed by the LabVIEW programming Language.

Highlights

The identification of the plasma shape and the position in real-time is important during the operation of the tokamak to achieve long time discharge
The computational code and software have been developed and installed in the system according to the overall design; hardware configuration, data flow, data acquisition, error correction, data sharing and calculation mechanisms
The system can display the actual shape of the last closed flux surface of the poloidal cross-section and its position on the major radius at a big screen placed inside the tokamak control room

Summary

Introduction

The identification of the plasma shape and the position in real-time is important during the operation of the tokamak to achieve long time discharge. By observing the temporal behaviors of the plasma shape and position in real-time, the experimenters can get indications about what measures should be taken into account to achieve steady state operation as well as long time discharge [1]. In the Wendelstein 7-X (W7-X) fusion experiment, a real-time image diagnostic system has been developed to monitor the plasma-facing components (PFCs) that can permanently damage the tokamak plasma operations. This system has an alarm system to interlock the system [7]. In the Q-shu University experiment with steady-state spherical tokamak (QUEST), plasma control system (PCS) that is used to control and operation of the tokamak experiments has been upgraded to achieving long duration plasma sustainment [8]

Methods

Results

Conclusion