High-speed feedback control of an oscillating magnetic helicity injector using a graphics processing unit
K D Morgan1, A C Hossack1, C J Hansen1
1Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195, USA.
The Review of Scientific Instruments
|July 10, 2021
Summary
A new real-time control system precisely manages plasma parameters in an oscillating magnetic helicity injector. This system enables advanced study of plasma discharges by controlling waveform amplitude and phase.
Area of Science:
- Plasma Physics
- Control Systems Engineering
- Computational Electromagnetics
Background:
- Precise control of bulk plasma parameters is crucial for studying plasma dynamics.
- Oscillating magnetic helicity injectors require sophisticated real-time feedback for stable operation.
- Existing control systems may lack the speed and precision needed for advanced plasma research.
Purpose of the Study:
- To develop and demonstrate a real-time control system for bulk plasma parameters.
- To achieve precise control over amplitude, phase, and offset in an oscillating magnetic helicity injector.
- To enable the study of new plasma discharge regimes through advanced waveform control.
Main Methods:
- Implementation of a control system on a high-performance graphical processing unit (Nvidia Tesla P40).
- Utilizing a Pulse Width Modulation (PWM) controller for real-time adjustments.
- Employing a three-parameter proportional integral differential (PID) controller with a 12.8 µs control loop period.
- Achieving an input digitization rate of 10 MS/s.
Main Results:
- The control system successfully managed plasma parameters (amplitude, phase, offset) in real-time.
- An oscillating plasma waveform at 16.6 kHz was generated and stabilized near RLC circuit resonance.
- The temporal phase of the injector waveform was maintained within a 10° tolerance.
- Control over the toroidal modal structure of magnetic perturbations was demonstrated.
Conclusions:
- The developed real-time control system offers precise and rapid manipulation of plasma parameters.
- This advancement facilitates the investigation of novel plasma discharge characteristics.
- The system's capabilities open new avenues for research in magnetic helicity injection and plasma physics.
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