Development of a NI-PXI RTC & DAQ system for MHD mode control on TEXTOR Fusion Reactor

Austin Consultants were brought in to assist MeasX with the completion of the project over a four month period at the Juilch research centre, Germany.

The Challenge
To locate, track and remove the magnetic “cold” Island locations in the plasma to create an unperturbed temperature profile during MHD stablisation so that a more power efficient process would occur.

The Solution
This required real time accurate detection of the islands, deterministic data processing for the tracking of ECRH power separation with respect to island location, synchronisation of the power modulation with respect to island rotation and then firing of the Gyrotron 140Ghz, 800KW microwave gun into the plasma to remove the island at a pulsed rotation frequency.

The system needed guaranteed accuracy and a fast response time with control robustness and stability. Therefore a real time data acquisition, analysis and control system combining National Instruments hardware with DAQ electronic customised hardware for signal processing was the required solution. It required phase and frequency detection from the ECE fluctuations in the plasma allowing island recognition due to fluctuation in electron temperature. From this analysis the system required controlled accurate steering of the SCRH launcher to rotate the mirrors in order to track the island, implementing a PID loop off the back of a simulink profile simulation and then modifying it for real world friction along a 56 degree sweep of rotation in 100ms. This code was deployed  down onto the FPGA for deterministic performance. The frequency of the rotating plasma was then calculated using fast Fourier transforms and correlation techniques and which was also deployed onto the FPGA. Once the frequency of the rotating island in the plasma was confirmed the Gyrotron microwave gun was then fired in a pulse train format until the island was removed.
The whole system was implemented using LabVIEW, LabVIEW FPGA and LabVIEW Real time with the simulation modules produced in Simulink and LabVIEW simulation module.

NI Hardware included
 

• CPU PXI – 8196 RT Embedded Controller
• 2 x PXI – 8336 MXI 4
• 4 x PXI – 6123 S-series DAQ cards
• 2 x PXI – 7833 R FPGA Reconfig. I/O
• Real time data processing (island localization)
  
   

TEXTOR Fusion Reactor