CODAC also works on KSTAR
3 Sep 2012
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Mikyung Park and the KSTAR team
KSTAR is a natural target for evaluating and validating CODAC technologies.
Recently, the standard ITER CODAC (Control, Data Access and Communication) technologies successfully demonstrated their adaptability and operability for tokamak control at the Korea Superconducting Tokamak Advanced Research (), in operation since 2008.
Like ITER CODAC, the KSTAR control system uses EPICS as middleware for tokamak control and operation. Therefore, KSTAR is a natural target for evaluating and validating CODAC technologies as has been identified in the Memorandum of Understanding between ITER Organization and National Fusion Research Institute (NFRI).
During the last 15 months, the KSTAR control team has implemented a duplication of the fuel control system and a part of the plasma control system using CODAC technologies (standardized hardware and CODAC Core System). On 26 July, a first test was successfully executed by injecting deuterium gas into the vacuum vessel based on pre-configured waveforms from the plasma control system.
The project will be completed in November by using real density signals from a millimetre-wave interferometer and closing the density feedback control loop during the KSTAR plasma operation.
Graph shows measured signals such as piezo valve drive, gas flow-out and vacuum pressures as control command form plasma control is applied.
The KSTAR fuelling system operates with four different gases for plasma creation, wall cleaning and diagnostics. For the experiment, one piezo-electric valve (for deuterium gas) was selected as an actuator. Various pre-configured patterns were used as reference inputs to the plasma control system for controlling the fuel injection. The plasma control system was implemented on a high performance computer using ATCA form factor, CODAC standard real-time operating system (MRG-R) and MARTe real-time framework originally developed at JET.
The density signal was simulated by programmable waveforms. A CODAC standard fast controller (fuel controller) was also implemented to control the embedded piezo-valve controller and to acquire diagnostics signals such as vacuum vessel pressure, gas flow, valve drive voltage, etc. at 10 kHz. The plasma control system communicated with the fuel controller over the standard CODAC real time network at 1 kHz.
As the measurements from the first test showed identical results as the KSTAR fuelling system, it was confirmed that the technologies adopted or being considered for ITER CODAC were applicable for the plant control at tokamak, that is, CODAC is heading in the right direction.